• Fundamental coal demand prediction under the goal of carbon neutrality in 2060

    WANG Bing;LI Lu;XIAN Yujiao;YU Pengwei;HAO Wenchao;Center for Sustainable Development and Energy Policy Research,School of Energy and Mining Engineering,China University of Mining and Technology-Beijing;School of Management,China University of Mining and Technology-Beijing;

    The proposal of carbon peak and carbon neutral targets put forward a huge challenge to the carbon emission reduction of the coal industry, and the coal industry will face all-round and in-depth adjustment. In order to ensure the energy security, it is very important to carry out stable and reliable carbon emission reduction in the coal industry in an orderly manner. Based on coal flow chart and energy consumption level of numerous coal consumers, the key areas of coal consumption were identified and the coal fundamental demand projection model was established based on the department scenario analysis method. And the fundamental coal requirements of different coal consumption sectors(electricity, chemical, steel, cement, heating) were systematically analyzed under the constraints of carbon neutrality and energy security and the reliability of the results by analogy was demonstrated. The results reveal that the coal production capacity demand in 2030,2040 and 2050 will be within the range of 2 120 million-2 870 million, 1 400 million-2 090 million and 660 million-1 310 million tons of standard coal respectively; in 2060,the basic coal requirement will be within the range of 280 million-610 million tons of standard coal. the demand for coal production capacity will increase significantly to 730 million tons of standard coal in the intensive security situation that can guarantee supply of power, oil and gas. The power sector and coal chemical sector have a great impact on the demand for coal production capacity and there is high uncertainty. In 2060,the coal guarantee demand of the power sector and coal chemical sector will reach 210 million-590 million and 30 million-110 million tons of standard coal respectively.Energy efficiency improvement, process optimization and output adjustment in other industrial sectors will reduce their coal demand, and coal will be transformed from industrial fuel to carbon based raw materials.Compared with the coal development history of major international countries, China′s coal consumption will reach 290 million and 560 million-760 million tons of standard coal respectively in 2060. The reliability of prediction result is high. The sharp decline in total coal production, the optimization of production and consumption structures, the extension of coal industrial chains, and the development of low-carbon technologies will be the typical characteristics of the sustainable development of the coal industry under carbon neutrality goal. Facing the long-term development trend under the background of carbon neutralization, the coal industry should be optimized from production capacity evaluation, industrial chain innovation, energy conservation and emission reduction, power security guarantee and coal flexible supply.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 13839K]

  • Research progress in carbon deposition resistance of nickel-based catalysts for carbon dioxide reforming of methane

    MA Qingxiang;ZHANG Jing;WANG Yijie;LYU Linghui;FAN Hui;ZENG Chunyang;ZHAO Tiansheng;State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering,Ningxia University;China Petroleum and Chemical Industry Federation;

    Global warming caused by the greenhouse effect poses a serious threat to the human living environment. Dry reforming of methane(DRM) reaction uses two major greenhouse gases as feedstock to produce syngas with H_2/CO molar ratio close to 1 while consuming methane and carbon dioxide, making it an ideal feedstock for Fischer-Tropsch synthesis to produce liquid fuels or high value chemicals. Nickel-based catalysts are the most widely used catalysts for DRM reaction, but they are prone to deactivation due to sintering and carbon accumulation under high temperature, hindering their industrial application. In view of the inactivation of nickel-based catalysts due to carbon deposition, thermodynamics and reaction mechanisms of DRM reactions were reviewed, carbon deposition inactivation mechanisms was analysed, and catalyst active components, supports, auxiliaries and preparation methods were discussed. Thermodynamic analysis of DRM reaction shows that high temperature and low pressure favor a shift in equilibrium towards syngas production. Reverse water-gas shift reaction consumes CO_2 from the feedstock to produce CO,so in general the CO_2 conversion rate is higher than the CH_4 conversion rate, and the H_2/CO molar ratio is less than 1. At a reaction temperature of 557-700 ℃,the carbon deposition mainly comes from the carbon monoxide disproportionation reaction and the methane cracking reaction. Reaction temperature above 700 ℃ are not conducive to carbon monoxide disproportionation reactions and carbon deposition will mainly originate from methane cracking reaction. Amorphous carbon can be eliminated by hydrogen or oxygenated species at temperatures below 573 K. On the other hand, graphite carbon requires gasification at higher temperature to be eliminated and it is the main cause of catalyst deactivation. Increasing the CO_2/CH_4 molar ratio in the feed gas or adding water vapour or oxygen to the feed gas can reduce carbon deposition to some extent, but to solve the problem of carbon accumulation is the study of catalysts. Bimetallic nickel-based catalysts form alloys at certain ratios, which act synergistically in the activation of CH_4 and the decarbonisation process. The limiting effect of the mesopore structure in support allows the nickel particles to be present in the catalyst pores as much as possible, which helps to reduce the size of nickel metal particles and to enhance the metal-support interaction to a certain extent, thus improving the catalytic activity and resistance to carbon depositionn in the DRM reaction. Supports with special redox properties and extraordinary oxygen storage capacity(OSC) can use oxygen vacancies to facilitate the activation and dissociation of CO_2,reducing catalyst deactivation due to carbon deposition by oxidation of surface carbon to CO. The use of alkaline supports or auxiliaries can increase the catalyst alkalinity appropriately so that the carbon deposition rate of the methane cracking reaction is comparable to the carbon elimination reaction rate, thereby reducing carbon accumulation. New catalyst preparation methods, reaction process enhancement and reaction process coupling can all be effective in reducing and eliminating reaction carbon accumulation. Studies show that appropriate modifications to the composition and structure of catalyst can significantly improve the resistance of the catalyst to carbon accumulation in the DRM reaction.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 32653K]

  • Review of nickel-based CH_4-CO_2 reforming catalysts

    ZHANG Yunfei;ZHANG Xiaodi;WANG Ying;LI Guoqiang;ZHANG Guojie;State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology;

    The use of fossil fuels leads to a large amount of CO_2 greenhouse gas emissions, which has caused a series of environmental and climate problems. The treatment and utilization of the major greenhouse gases CO_2 and CH_4 have become urgent. CH_4-CO_2 dry reforming(DRM) converts CO_2 and CH_4 into syngas, an industrial feed gas, enabling the utilization of both greenhouse gases. Precious metal catalysts exhibit excellent catalytic activity and anti-coking performance for DRM reactions, but their applications are limited due to limited resources and high prices. The catalytic activity of non-precious metal Ni-based catalysts is not only comparable to that of noble metals, but also has abundant sources and low prices. It is one of the most likely to be industrialized catalysts. However, Ni-based catalysts have the problems of easy sintering and carbon deposition. Researchers have carried out a lot of modification work on Ni-based catalysts to improve their catalytic activity, anti-sintering ability and anti-carbon deposition ability. In order to gain a more comprehensive understanding of the DRM reaction and its Ni-based catalysts, the thermodynamics, reaction mechanism and kinetics of the CH_4-CO_2 reforming reaction were reviewed. Thermodynamic studies have shown that high temperature and low pressure are favorable for the DRM reaction; but so far there is no unified reaction mechanism suitable for all catalysts, and different catalysts have different reaction mechanisms and rate control steps. The main factors affecting the performance of Ni-based catalysts, such as carriers, additives, preparation methods and calcination temperature, were further analyzed. The interaction force and surface acidity and alkalinity have a significant effect, which in turn affects the activity and stability of the catalyst. The progress of Ni-based dry reforming catalysts with new structures was introduced. It is found that the confinement effect of the catalysts with new structures could effectively improve the anti-sintering and anti-coking abilities of the catalysts. Finally, the future research direction of Ni-based DRM catalysts was prospected.It provides new ideas for the design and development of new efficient catalysts in the future.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 23637K]

  • Research progress in new confined catalytic materials for methane carbon dioxide reforming

    WANG Jing;CAO Zhihua;PAN Yaqing;MAO Yiru;ZHANG Lizhi;LIU Wenming;PENG Honggen;College of Chemistry and Chemical Engineering,Nanchang University;College of Resources and Environment,Nanchang University;

    With the continuous increase of carbon dioxide emissions, mainly from the burning of coal and oil, the ecosystem is seriously threatened. Methane is a major component of shale gas and natural gas, and is an important feedstock for producing liquid fuels and high-value chemicals. But it is also a greenhouse gas, and the greenhouse effect of methane is 25 times that of carbon dioxide. The methane-carbon dioxide reforming technology has attracted much attention because of its simultaneous conversion of methane and carbon dioxide into syngas CO and H_2. However, the sintering and aggregation of catalysts will occur during the reaction process, so the design and preparation of catalysts with excellent resistance to carbon accumulation and sintering is the key problem to be solved urgently in methane carbon dioxide reforming reaction. From the point of view of limited domain, the design of catalysts with excellent performance and their application in chemical reactions widely concerned. In this review, the research status of several kinds of confined high performance methane carbon dioxide reforming catalysts were introduced, including pore confined catalysts, core-shell confined catalysts, lattice confined catalysts, surface space confined catalysts and multiple confined catalysts. In addition, the performance of its application in reforming methane with carbon dioxide was described. Finally, the future development direction of application of confined strategy in the development of high-performance reforming catalysts was prospected. The pore-channel confinement affects the accessibility of reaction species and active center, active surface area and structural stability of the catalyst. The core-shell confinement can effectively promote the contact between the reactants and the active center and enhance the interaction with the active center. The lattice limits can effectively anchor precious metals or non-precious metals to the spatial framework of regular arrangement and improve the dispersion of active centers. Surface space confined catalysts with high specific surface area, highly ordered pore structure and mesoporous carriers with narrow pore size distribution(in the nanometer range) can provide a large number of catalytic active sites and stabilize metal nanoparticles. The multiple confinement can well limit the active center in the catalyst, reduce its exposure and improve the anti-carbon accumulation ability of the catalyst. Confined catalysts are widely used in the design and preparation of catalysts. Confined catalysts provide a constrained environment(physical or chemical) for the catalytic reaction system, which provides an idea for rational design of high thermal stability catalysts in the future. In the future, it is expected to pass the confined effect(especially surface space confinement and multiple confinement strategy) to regulate the design catalyst used in high temperature and high pressure carbon dioxide reforming of methane, and further explore the catalyst used in carbon dioxide reforming reaction mechanism(carbon dioxide is how to provide active oxygen for methane),which provides a new catalyst for the industrial application of methane carbon dioxide reforming reaction.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 13030K]

  • Preparation of biomass nitrogen-doped carbon material catalyst and its catalytic performance for CO_2 reforming of CH_4

    MA Xiao;QIN Xiaowei;ZHANG Xiaodi;ZHANG Guojie;Luoyang Ruize Petrochemical Engineering Co.,Ltd.;State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology;

    Using wood chips as carbon source, urea as nitrogen source and KOH as activator, a series of nitrogen-doped biomass carbon CH_4-CO_2 reforming catalysts were prepared. The structure and properties of fresh and spent catalyst samples were analyzed by surface pore structure analyzer, electron microscopy, infrared, and thermogravimetric characterization. The effects of pore structure, nitrogen content, nitrogen species(pyridine nitrogen, pyrrolic nitrogen and graphitic nitrogen) and basic sites on the reforming performance were investigated. The study found that nitrogen doping can significantly increase the nitrogen and basic site content of biomass carbon materials, providing more active sites for the reforming reaction. The nitrogen content of the biomass char material(BC-750/3.5-N) prepared by post-processing nitrogen was as high as 26.35%. The in-situ nitrogen doping can promote the activated pore formation of KOH,so that the sample NBC-750/3.5 can obtain a large number of micropores or narrow micropores. The specific surface area and pore volume are 1 981.53 m~2/g and 1.08 mL/g, respectively, which are conducive to the adsorption of raw gas. Meanwhile, the characterization results show that the proportion of pyridinic nitrogen and pyrrolic nitrogen in the NBC-750/3.5 catalyst samples prepared by in-situ nitrogen doping is relatively high, which are 31% and 50%,respectively. The pyrrolic nitrogen is favorable for CO_2 adsorption, and the pyridine nitrogen is favorable for molecular activation, so the prepared carbon material catalyst exhibits excellent catalytic performance. After 10 hours of catalytic reforming, the conversions of CH_4 and CO_2 remain stable at about 45% and 62%. It is also found that after the reforming reaction, the proportion of pyridine nitrogen and pyrrolic nitrogen decrease, and the proportion of graphitic nitrogen increases. By changing the preparation method of biochar and nitrogen doped method, the existence form of nitrogen containing groups can be more accurately regulated, so that high activity and stability of carbon-based non-regenerated catalytic materials can be obtained through controlled preparation.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 28807K]

  • Preparation and performance of embedded type Ni@S1 catalyst for CH_4-CO_2 reforming reaction

    GAI Xikun;YANG Dan;ZHU Jicheng;LUO Meiyu;MA Qingxiang;XING Chuang;LYU Peng;ZHANG Liangquan;Zhejiang Key Laboratory of Agricultural Products Chemistry and Biological Processing Technology,College of Biological and Chemical Engineering,Zhejiang University of Science and Technology;State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering,Ningxia University;

    CH_4-CO_2 reforming reaction can realize the utilization of CH_4 and CO_2,which is of great significance to curb the greenhouse effect and environmental protection. Developing the reforming catalysts with low cost, high activity and high stability is of critical importance. Supported Ni/Q10(amorphous SiO_2 with 10 nm pores) and embedded Ni@S1(Silicalite-1) catalysts were prepared by impregnation method and grinding-crystallization method, respectively, and they were used in CH_4-CO_2 reforming reaction. The structure of the catalyst was characterized by XRD,BET,IR,H_2-TPR,NH_3-TPD,XRF,XPS,SEM,TEM and TG. It is found that the grinding-crystallization method can effectively control the particle size and dispersion of active metal Ni in Ni@S1 catalyst, and enhance the interaction between active metal phase and carrier. The intercalation structure can reduce the carbon deposition of the catalyst, after reacting at 700 ℃ for 6 h, the carbon deposition of 5% Ni@S1 catalyst is only 46.83% of that of 5% Ni/Q10 catalyst. The activity of the catalyst was evaluated in a continuous fixed-bed reactor(CH_4/CO_2/Ar=44.0/47.2/8.8,F_(in)=40 mL/min, T=700 ℃). It is found that the instantaneous conversion of CH_4 over 5% Ni@S1 and 5% Ni/Q10 catalysts are 72.82% and 67.24%,respectively, which decreases by 1.05% and 7.99% compared with the initial conversion rates. The instantaneous conversion rate of CO_2 are 79.06% and 76.69% respectively, which are 1.16% and 4.54% lower than the initial conversion rates. The activity and stability of embedded Ni@S1 catalyst for CH_4-CO_2 reforming reaction are superier to those of supported Ni/Q10 catalyst.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 24469K]

  • Effects of power supply parameters and gas composition on transformation of coal bed methane by low-temperature plasma

    ZHU Lihua;ZHANG Yue;TIAN Yaoyao;XU Feng;School of Safety Engineering,Heilongjiang University of Science and Technology;

    Low temperature plasma technology is an effective means to achieve carbon sequestration and emission reduction of methane. However, the research on coal bed methane has not yet been carried out in-depth. To explore the influencing factors and action rules of transformation of coal bed methane by low-temperature plasma, the CH_4-N_2-O_2-H_2O experimental system was constructed with corundum as discharge medium, threaded stainless steel rod as high pressure electrode, wire mesh as low pressure electrode. The influence of input voltage, discharge frequency, methane volume percentage on transformation of methane and product formation were investigated under the conditions of a 1 mm discharge gap and a discharge area of 200 mm in length. And based on the in situ diagnosis of the emission spectra of the active species during the reaction, the pathways of the main products were analyzed. The results show that the main products are hydrogen, carbon monoxide, carbon dioxide, methanol, ethylene, ethane and other C_2 hydrocarbons. The methane transformation and product formation are affected by the input voltage, discharge frequency and CH_4 volume fraction, because the input voltage changes the injection energy and energy loss of DBD system, discharge frequency changes the amount of streamer discharge in the reactor and volume percentage of methane changes the oxidation environment. In the range of experimental research, the optimal conditions are input voltage 75 V,discharge frequency 9.8 kHz; the optimal volume percentage of methane is 35.4% when the yield of methanol is used as the index. Active particles such as CH_3·,CH_2·,CH·,C·,O·,OH·,H_γ,H_β,H_2 and H_α are generated during plasma reaction. These active particles interact with steady-state molecules and interact with each other to form product molecules. The results are of great significance to further study the process conditions and reaction mechanism of low-temperature plasma activation coal bed methane.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 9179K]

  • Current status and prospects of research on ash slagging in heated area of coal-fired power plant boiler unit

    LIU Pengyu;LI Debo;LIU Yanfeng;CHEN Zhaoli;FENG Yongxin;LIAO Hongkai;Department of Power Engineering,North China Electric Power University;China Southern Grid Power Technology Co.,Ltd.;

    Ash and slagging on the heated area of the boiler unit of coal-fired power plants often cause major safety accidents such as flameout, reduced boiler efficiency, and even shutdown of the boiler due to over-temperature bursting.Therefore, the problem of ash accumulation and slagging has become an urgent problem to be solved in the actual engineering of coal-fired power plants. The author reviewed the actual engineering and numerical simulation research status of ash and slag based on the heated area, and reviewed the mechanism and solution methods, after horizontal comparison and that the research and development of intelligent soot blowing system based on the direction of intelligent monitoring technology in ash accumulation is an important future research direction, and the mathematical model should be proposed to improve the prediction accuracy of semi-convective and semi-radiative heated surface considering the combined effect of convection and radiation.Since the phenomenon of ash accumulation and slagging is influenced by a variety of factors, and most of the current studies focus on one or two methods of investigation, there is a need to develop a comprehensive optimization program that integrates multiple influencing factors in a synergistic manner in the area of slagging.The numerical simulation of ash accumulation and slagging problem can be explored by finite reaction rate/vortex dissipation model to explore the improvement of two or more types of coal, and ANSYS Fluent extension can be developed to improve the accuracy of traditional numerical simulation, so as to further provide technical guidance to the engineering problems of ash and slagging in boiler unit heating area.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 7130K]

  • New progress of algorithm for three-dimensional temperature field in large scale furnace measured by thermal radiative imaging

    YAN Huibo;TANG Guangtong;LI Lujiang;WANG Chaoyang;LI Xin;YAN Xiaopei;LI Zhicong;LOU Chun;State Grid Hebei Energy Technology Service Co.,Ltd.;State Key Loboratory of Coal Combustion,School of Energy and Power Engineering,Huazhong University of Science and Technology;

    The three-dimensional combustion field in the large-scale furnace is closely related to the safety, economy, and pollutant emission level of combustion process. Compared with other visualization monitoring technology of three-dimensional temperature field, such as acoustic tomography and absorption spectrum tomography, the thermal radiation imaging method has a compact system and easy to implement, with high temporal and spatial resolution, and has great application potential. In this paper, the principles of thermal radiation imaging in large-scale furnaces were introduced, the ill-posedness of the inverse problem of radiative transfer was analyzed, and the progress of the algorithm for the inverse problem of radiative transfer was reviewed. The construction of a large-scale furnace thermal radiation imaging model uses a thermal radiation imaging matrix to link the radiation energy distribution received by the sensor with the temperature field and radiation characteristics of the medium and wall. The critical step to calculating the thermal radiation imaging matrix is to obtain the scattering or reflection share of the medium elements and wall elements. The DRESOR method and the inverse Monte Carlo method can solve the problem. Judging by the condition number of the thermal radiation imaging matrix, the inverse problem of radiative transfer is ill-posedness. As a result, the solution is non-uniqueness or even non-existence, and minor measurement errors will cause the instability of the reconstructed temperature field. Solving this kind of ill-posed problem is mainly divided into optimization methods and regularization methods. Optimization methods can divide into traditional optimization methods and intelligent optimization methods. Traditional optimization methods are based on gradient calculations, which reduce the objective function through repeated iterative calculations, such as the Least-Squares and Conjugate Gradient. However, this type of method relies heavily on the initial value, requires the derivative of the objective function, and cannot obtain the optimal global solution. Intelligent optimization methods are based on probabilistic search, which starts from a certain random solution and looks for the optimal solution in the solution space with a certain probability according to the corresponding algorithm mechanism. There is no need to know the exact mathematical model of the optimization problem and not necessarily solve the gradient of the objective function. It can also divide into bio-colony simulation and bio-individual simulation. The former includes Particle Swarm Optimization(PSO),Genetic Algorithm(GA),and Ant Colony Algorithm(ACO),etc. It needs to construct an objective function and takes a long time to search for the optimal solution. The latter includes Artificial Neural Networks(ANN),Support Vector Machines(SVM),etc. The mathematical equations of the mapping relationship of the prediction problem are not necessary to know in advance; the result closest to the actual output value can obtain after training. But the quality of the training data set is one of the critical factors affecting the prediction accuracy. Regularization methods are also common for ill-posed problems, including Tikhonov regularization(TR),Truncated Singular Value Decomposition(TSVD),etc. The solution of a family of well-posed problems adjacent to the original ill-posed problem is used to approximate the solution. This method has been used to reconstruct the three-dimensional temperature field in coal-fired furnaces and has high reconstruction accuracy and efficiency. Although thermal radiation imaging needs to consider the influence factors such as optical thickness, it can better reproduce the distribution characteristics of the actual temperature field in the furnace within a certain scope of application. And it considers the radiation transfer equation in the three-dimensional space, which is essentially a three-dimensional monitoring technology. The development of imaging technology(light field camera, multi/hyperspectral imager, etc.) has also pointed out a new development direction for thermal radiation imaging to reconstruct the three-dimensional temperature field in large-scale furnaces.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 4552K]

  • Physical and chemical properties of coal pyrite and flotation desulfurization

    KANG Wenze;MA Zihang;School of Mining Engineering,Heilongjiang University of Science and Technology;

    Coal is the main energy in China and has been supporting the rapid development of the national economy. However, sulfur in coal has seriously affected the clean utilization of coal and caused serious environmental pollution. Pyrite is the main form of sulfur in coal. Its surface properties and removal methods are very important for the clean utilization of coal. This paper analyzes the differences of physical and chemical properties of pyrite in coal measures, expounds in detail the diversity of occurrence states, the complexity of chemical properties and the non-uniformity of crystal properties of pyrite, analyzes the influence of physical and chemical properties of pyrite on desulfurization, and points out that taking specific removal methods for different physical and chemical properties is the focus of physical desulfurization research. The pretreatment methods of flotation desulfurization are systematically introduced. The research status and development trend of ultrasonic method, microwave method and microbial method are described in detail. Ultrasonic can change the surface properties of minerals and the properties of pulp; microwave method improves the selectivity of slime flotation; microbial method has the advantages of less pollution and less energy consumption. The combination of microwave and ultrasonic can reduce the desulfurization cost and maximize the desulfurization rate. Therefore, the combination of microwave and ultrasonic is the most promising method. The flotation desulfurization effect of pH regulator, organic inhibitor and combined inhibitor is discussed. The price of pH regulator is low, and the organic inhibitor is effective in environmental protection. The combined inhibitor can have the advantages of both pH regulator and organic inhibitor, which is an important research direction of pyrite flotation inhibitor.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 6596K]

  • Viscosity-temperature characteristics of coal and coal blending

    BAO Jinyuan;FENG Changzhi;DAN Shulin;LIU Zhen;FANG Xinhui;AN Haiquan;CHN Energy Yulin Chemical Industry Co.,Ltd.;National Institute of Clean-and-Low-Carbon Energy;

    The viscosity-temperature characteristics of coal ash have an important influence on the stable slag discharge in the entrained flow gasification process. The viscosity-temperature characteristics of Xiwan coal, Xiaobaodang coal and their blends were studied using a Theta high-temperature rotational viscometer. Combined with the ternary phase diagram analysis of ash components, the coal proportion suitable for entrained flow gasification technology was determined. The results show that the slag of Xiwan coal is crystalline slag, and when the temperature is lower than the critical temperature T_c,the viscosity of the slag increases sharply, causing difficulty in slag discharge. By Xiaobaodang coal is added to Xiwan coal, the acid-aluminum ratio and silica-aluminum ratio of ash gradually decrease, the ash composition changes from yellow feldspar to calcium feldspar, and the ash slag form changes from crystalline slag to glass slag, and the optimal silica-aluminum ratio is 2.35-2.97,the acid-aluminum ratio is 1.05-2.08 and the calcium-iron ratio is 0.70-1.98.With the content of Xiaobaodang coal in the blended coal exceeding 30%,the temperature difference corresponding to the ash slag in the viscosity of 2.5-25.0 Pa·s is higher than 100 ℃,and the slag type change tends to be stable. At the same time, the gasification process requires that the critical temperature of ash slag T_c is not in the temperature range of corresponding temperature when the viscosity of ash is 2.5-25.0 Pa·s in order to ensure the stability of slag discharge, therefore, the ratio of the coal blends of Xiwan coal and Xiaobaodang coal suitable for entrained flow gasification applications is 3∶7 or 7∶3.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 9208K]

  • Synthesis and properties of zeolite-TiO_2 photocatalyst based on fly ash

    XUE Haiyue;WANG Lianyong;LIU Xiangyu;HAN Jianli;School of Metallurgy,Northeastern University;State Key Laboratory of Eco-industry for Environmental Protection;

    Fly ash, as a kind of solid waste, has the advantages of low cost and wide sources, and can be widely used to prepare zeolite as catalyst carrier, realizing its high value utilization and protecting the ecological environment at the same time. The X-type zeolite-TiO_2 composite photocatalyst was prepared from solid waste fly ash and TiO_2 was successfully loaded during the synthesis of zeolite, which saved the preparation cost compared with the loading method after synthesizing zeolite. A 4-factor, 4-level orthogonal test was used to explore the best preparation conditions of the catalyst with the mass ratio of titanium dioxide to fly ash, the mass ratio of fly ash to sodium hydroxide, the mass and volume ratio of fly ash to ultrapure water, and the crystallization time as the influencing factors, and the removal rate of methylene blue as the target function, and the best catalyst was characterized by XRF,XRD,FTIR,and SEM. The experimental results show that the best catalyst performance is achieved when m_1/m_2 is 1.0∶2.9,m_3/m_2 is 1.5∶1.0,the ash-water ratio is 1∶10,and the crystallization time is 24 h(where m_1,m_2,and m_3 are the masses of TiO_2,fly ash, and NaOH,respectively). The methylene blue simulated waste solution with a mass concentration of 10 mg/L is prepared, 0.25 g/L of catalyst under this group of conditions is added, and the reaction is carried out at 30 ℃ for 1 h. The removal rates of methylene blue are 42.47% and 98.15% under the dark and UV irradiation conditions, respectively, indicating that the X-type zeolite-TiO_2 composite photocatalyst synthesized by this method has a good treatment of dye molecules in printing and dyeing wastewater. Moreover, fly ash belongs to thermal power plant waste, and a more ideal catalyst material is prepared under low-cost conditions to realize waste to waste.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 21040K]

  • Thermogravimetric analysis and kinetic study on blended fuel of semi-coke and straw

    WU Pengkui;HAN Kuihua;School of Energy and Power Engineering,Shandong University;Shandong Engineering Laboratory for High-efficiency Energy Conservation and Energy Storage Technology & Equipment,Shandong University;

    The existing semi-coke has the advantages of high fixed carbon, low ash, low sulfur and low phosphorus, but it has low volatile and slow ignition. Adding a small amount of biomass into the semi-coke fuel can effectively improve its combustion performance, reduce the emission of coal-fired pollutants, and optimize the utilization status of biomass straw. In this paper, the combustion characteristics of three kinds of semi-coke, wheat straw and corn stalk alone and mixed fuels were studied by thermogravimetric analysis. The effects of the types of mixed samples and mixing ratio on the ignition temperature, burnout temperature, combustion characteristic index and heat release rate of mixed fuels were analyzed. The optimal mixing ratio was determined. The results show that the combustion effect of the mixed fuel is closely related to the type and proportion of the mixed fuel. The combustion properties of the five samples are wheat stalk, corn stalk, Fugu semi-coke(SC1),Datong semi-coke(SC3) and Inner Mongolia semi-coke(SC2),in descending order. The combustion properties of SC1 mixed with corn stalk are better than those of other mixed fuels. Compared with the original sample, the ignition temperature and burnout temperature of the fuel are reduced by about 200 ℃ and 40 ℃,respectively, and the comprehensive combustion characteristic index is about 1.5 times of the original sample. When the mixing ratio of SC1/straw is 8∶2,the ignition characteristic index is only 0.625,which is lower than the original sample′s ignition characteristic index(0.979). The actual value of the first wave peak is also less than the theoretical simulation value. The mixed fuel has inhibitory effect on the volatilization analysis of straw in the low temperature section. With the increase of the straw mixing ratio, the promoting effect is greater than the inhibiting effect. The first wave peak migrates and increases, while the second wave peak decreases. When the mixing ratio is 6∶4,there is a brief increase at the second wave peak. It is possible that the increase in the proportion of straw and the cracking of a large amount of flammable semi-coke results in the acceleration of combustion in a short time. Mixing a certain proportion of straw in the semi-coke is beneficial to reduce the activation energy of the fuel in the main combustion stage, but the improvement of combustion performance is limited with the increase of the mixing proportion. When the mixing ratio of SC1 and corn stover is 6∶4,the activation energy of SC1 is reduced by 36 kJ/mol. When the mixing ratio of SC1 and corn straw is 7∶3,the heat release rate of the blended fuel is significantly higher than that of other blended fuels. Combined with its combustion characteristics, it can be found that the fuel with this mixture ratio has the best combustion effect.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 14675K]

  • Numerical simulation of co-firing characteristics of coal and biomass in a 660 MW boiler

    WANG Jun;LONG Shenwei;MA Tongsheng;NIU Shengli;WANG Yongzheng;HAN Kuihua;LU Chunmei;School of Energy and Power Engineering,Shandong University;Shandong Fengyuan Biomass Power Co.,Ltd.;

    As a renewable carbon-neutral energy, biomass is an excellent substitute for fossil energy. The rational utilization of biomass energy is an important way to achieve the "carbon peaking and carbon neutrality" goal in China. Among the various utilization technologies of biomass, co-firing biomass in coal-fired boilers can not only reduce the consumption of fossil fuels and the emissions of pollutants such as NO_x and SO_2,but also reduce the risk of the corrosion of the boiler tail heating surface caused by pure burning of biomass, which is an effective measure to improve the efficiency of energy utilization. In this paper, the 660 MW pulverized coal boiler was taken as the research object, and the numerical simulation software Fluent was used to study the co-combustion process of biomass and pulverized coal, the realizable turbulence model was used to describe the gas-phase turbulence, the eddy dissipation model was used to calculate the combustion of volatiles, and the influences of biomass injection location and particle size on combustion process and nitrogen oxide emission were investigated. The calculation results show that the addition of biomass can promote the combustion of pulverized coal to a certain extent, whereas the NO_x emission is reduced. When biomass is injected from the primary air vent at the bottom layer, it can release the reducing components such as volatile matter earlier, so that the NO_xemission reduction effect is better. The NO_x mass concentration in the flue gas at the furnace outlet is reduced by 18.4% from 298.92 mg/m~3 in the original working condition to 243.97 mg/m~3. Although the change of biomass particle size has little effect on the flue gas temperature, O_2 and CO volume fraction in the furnace, the excessive particle size will lead to the reduction of biomass particle burnout rate, thus reducing the required oxygen. As a result, the pulverized coal is easier to burn completely, and the NO_x mass concentration in the outlet flue gas increases.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 23156K]

  • Optimization of flow field structure and analysis on velocity nonuniformity of the desulfurization tower

    LI Weiwei;SONG Xian;ZHANG Lidong;CHEN Jiyu;SUI Yinjiang;HUO Yanming;Huaneng Chaohu Power Generation Co.,Ltd.;China IPPR International Engineering CO.,Ltd.;Engineering Research Center of Oil Shale Comprehensive Utilization Ministry of Education,Northeast Electric Power University;

    The uniformity of slurry spray in the desulfurization tower has an important influence on the distribution of flue gas and the desulfurization reaction. It is of great significance to study the velocity inhomogeneity of flow field and structure optimization in the desulfurization tower to improve the desulfurization efficiency. Therefore, the quantitative analysis index unevenness was put forward. The relationship between unit load and desulfurization efficiency was established. The inner structure of the tower was optimized. Numerical analysis was used to analyze the variation trend of heterogeneity with desulfurization efficiency. The internal flow field of desulfurization tower with inlet velocity of 3.0,3.4,3.7 and 4.0 m/s was studied. Inlet guide vanes were added and flow field optimization was carried out by using inclined grid flow homogenizing plate. The velocity distributions of horizontal and vertical sections at different heights in the tower were analyzed, and the dynamic pressure changes along the vertical direction were compared. The results show that the load and desulfurization efficiency shows a significant negative correlation in the fluctuation, and the variation tends of desulfurization efficiency and velocity unevenness are basically the same, under all working conditions. The velocity unevenness ω in the middle area decreases by 10%,the dynamic pressure difference of the main desulfurization reaction area decreases by about 70%,and the outlet velocity increases by 0.1-0.2 m/s. The optimization structure could improve the velocity distributions inside the FGD tower, increasing desulfurization efficiency and flow uniformity. Also, it could reduce the possibility of slurry being wrapped out of the tower and help reduce the flow resistance and running cost.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 29614K]

  • Effect of cobalt on the catalytic performance of industrial V-Mo/Ti de-NO_x catalyst

    CHANG Zhengfeng;LIU Yang;GAO Yibo;HUANG Li;ZONG Yuhao;WANG Hu;LI Jinke;HAN Pei;Datang Nanjing Environmental Protection Technology Co.,Ltd.;Instrumental Analysis Center,Inner Mongolia University of Science & Technology;

    In order to enhance the catalytic performance at low flue gas temperature and broad its catalytic activity temperature, cobalt modified industrial V-Mo/Ti De-NO_x catalysts were prepared by impregnation method. XRF,N_2-adsorption desorption, H_2-TPR,Raman spectrum and NH_3-TPD were used to characterize the catalysts. The denitrification performance and resistance to SO_2 and H_2O of the different catalysts were tested by a fixed-bed micro-reactor. The results show that the loading of CoO has little impact on the pore structure and crystal structure of V-Mo/Ti catalyst. The structures of VO_x and MoO_x species of V-Mo-Co/Ti catalysts are similar to that of the V-Mo/Ti catalyst. Suitable amount of CoO(0.28%) can lead to the enhancement of acidity of the catalyst, without decreasing the reducibility of the catalyst. As a result, the catalyst activity is improved. When the flus gas temperature is 280 ℃,the NO_x conversion of CO-2 catalyst with 0.28% CoO is above 80%. However, excessive loading of CoO might results in the coverage of active sites by CoO,which reduces the chances of contact between VO_x species and the reaction gas. Consequently, the catalytic activity of the catalyst decreases. Besides, this study also finds that the SO_2 and H_2O resistance of the catalyst can be effectively enhanced by Co modification.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 7115K]

  • Removal performance of NO by high-content iron ash adsorbent modified by Mn and Ce

    LIANG Yunbo;ZHENG Xianrong;TAN Yuyao;FAN Baoguo;College of Electrical and Power Engineering,Taiyuan University of Technology;

    Flue gas denitration is the inevitable trend of air pollution control. The waste fly ash of coal-fired power plant can oxidize and remove NO_x. In order to further improve the adsorption capacity, fly ash should be properly modified. Mn-Ce high-content iron ash adsorbents were prepared by loading Mn and Ce components with high-content iron ash as matrix after alkali modification. The adsorption performance and denitration mechanism of modified high iron ash were studied by dynamic denitrification experiments. The results show that the high-content iron ash(DMA) is modified by 6 g CaO,0.1 mol Mn(NO_3)_2 and 0.02 mol Ce(NO_3)_3·6 H_2O,and named Mn(4)Ce(2)/Ca-DMA500,which has the highest denitration capacity, and the NO_x removal capacity can reach 823 μg/g. The essential reasons are as follows. First, during the process of preparing adsorbent by mechanical milling and hydration, the vitreous shell in the ash is destroyed and the FeO_x encapsulated in the vitreous body is exposed. The increase of Fe mass fraction contributes to increasing denitrification capacity of the adsorbents. After loading Mn and Ce, MnSiO_3 and Ca_2Fe_2O_5 are formed on the surface of the carrier. Hollow nanostructures composed of polycrystalline MnSiO_3 shells are often used in adsorbents and catalysts. Ca_2Fe_2O_5 has high catalytic oxidation activity due to the existence of a large number of disordered oxygen vacancies, which significantly increases the denitrification efficiency. Secondly, part of Mn exists in the amorphous form in the adsorbent, Mn and Fe/Ce in the adsorbent forms iron-manganese/manganese-cerium solid solutions, thereby improving the denitration ability. When the calcination temperature is 500 ℃,the pores of the adsorbent are evenly distributed, the pore structure is developed, and the specific surface area and pore volume are the best. CaMnSi_2O_6 has a higher degree of crystallization, and its surface impurities are decomposed or desorbed. Therefore, Mn-Ce high-content iron ash has better denitration performance, which is of great significance for flue gas denitration in air pollution control.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 20920K]

  • Environmental impact of gaseous organic pollutants emitted from 300 MW coal-fired power plant during life cycle

    YUE Pujie;MENG Lei;WANG Changqing;GU Xiaobing;BAI Yuyong;PENG Ya;YANG Qing;Datang Environment Industry Group Co.,Ltd.;School of Energy and Power Engineering,Huazhong University of Science and Technology;

    In recent years, the environmental impact assessment of coal power production industry in China has made some progress, but it mainly focuses on evaluating the impact of conventional pollutants, while the emission impact of unconventional gaseous organic pollutants has been neglected, resulting in underestimation of the harm to human health and the ecological environment. In order to study the environmental impact of gaseous organic pollutant emissions from coal-fired power plants, using the method of life cycle assessment(LCA), the energy and material consumption data list of gaseous organic pollutants emitted from typical 300 MW supercritical coal-fired units in China was compiled in detail by using Gabi software modeling, field data collection and literature data research, and the emission list results and life cycle environmental impact were comprehensively evaluated. The results show that the total amount of gaseous organic pollutants in the life cycle of 300 MW coal-fired power plant in 2017 is about 9.99×10~(-3) kg/MWh. Among them, the emissions from coal-fired power generation system are 3.87×10~(-3) kg/MWh, accounting for 38.69% of the total emissions. The indirect emissions from coal-fired power generation are 1.64 times of direct emissions, accounting for 62.16% of the total emissions. The standardized values of environmental impact types such as the photochemical ozone synthesis potential(POCP), terrestrial ecotoxicity potential(TETP), potential global warming effect potential(GWP), Marine ecotoxicity potential(MAETP), human toxicity potential(HTP), freshwater ecotoxicity potential(FAETP) and ozone depletion potential(ODP) cycles calculated from gaseous organic pollutant emissions of coal-fired power plants during the life cycle are 7.43×10~(-14), 9.05×10~(-17), 7.72×10~(-17), 5.21×10~(-17), 1.43×10~(-13), 4.13×10~(-16) and 3.21×10~(-18), respectively. Among them, POCP and human toxicity potential(HTP) are the most harmful types of environmental impact, accounting for 50.63% and 47.82% of the total potential value of environmental impact, respectively. Coal mining and washing and flue gas purification systems are the main contributors of POCP and HTP, respectively, and the change in coal consumption during the operation phase of the power plant has the greatest impact on the overall environment.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 9678K]

  • High temperature corrosion experiment on T91 and Super304H steel materials

    WANG Xiaolong;WANG Yongdong;LIU Junjie;LI Zheng;XIONG Xiaohe;Shenhua Shendong Coal Group Co.,Ltd.;MOE Key Laboratory of Thermo-Fluid Science and Engineering,Xi′an Jiaotong University;

    The boiler heating surface corrosion and over-temperature bursting seriously affect the boiler safe operation. Especially under the background of coal quality frequent variation, frequent operation adjustment matching the grid load, the heating surface leakage often occurrence, which threatens the stable operation of the units. To investigate the corrosion behavior characteristics of steel at high temperatures, two typical convective heating surface steels T91 and Super304 H were selected to compare their corrosion behavior characteristics under air, hydrogen sulfide and sulfur dioxide three different atmospheres. It is found that the anti-high-temperature corrosion performance of Super304 H steel is significantly better than that of T91 steel. Among the three atmospheres, the ratio of average corrosion rate between T91 steel and Super304 H steel ranges from 2 to 18. The corrosion rate of both steels is the highest under hydrogen sulfide atmosphere and the lowest under sulfur dioxide atmosphere. From the appearance of corrosion products, T91 steel base after corrosion appears obvious corrugation trace, the surface is not glossy and the boundary between corrosion products is obvious. Many pore structures and the cracks can be found and the larger needle like corrosion products show a falling off trend. In contrast, the obvious corrosion trace of Super304 H steel matrix can be seen only in the atmosphere of H_2S. In the atmosphere of SO_2 and air, the surface of the matrix is still flat and the corrosion is not obvious. The line scan analysis of the corrosion products shows that the corrosion layer of T91 is mainly composed of two corrosion layers, Cr_2O_3 and Fe_2O_3. While Super304 H is composed of three corrosion layers, Cr_2O_3,NiO and Fe_2O_3. In terms of the thickness of corrosion layer, that of Super304 H is only 11.94 μm, while that of T91 is 34.8 μm. It indicates that the addition of Cr and Ni can enhance the oxidation resistance of Super304 H. Although the corrosion rates of the two steels are different, according to the oxidation resistance level of GB/T 13303—1991《Test method for oxidation resistance of steel》,the two steels, belong to the oxidation resistance type.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 34666K]

  • Gas-solid corrosion characteristics of 316L alloy fiber fabric in SO_2 atmosphere

    DING Shouyi;HUANG Yaji;CHEN Kuixu;XU Ligang;FAN Conghui;HU Huajun;QI Erbing;DAI Wenxiao;Key Laboratory of Energy Thermal Conversion and Control of the Ministry of Education,Southeast University;Fujian Longking Co.,Ltd.;

    In the field of high-temperature dust removal, 316 L alloy fiber fabric has attracted widespread attention due to its reusability. However, the gas-solid corrosion characteristics and mechanism of 316 L alloy fiber materials are not clear, which has become a risk factor in practical applications. Based on the gas-solid corrosion characteristics of 316 L alloy fiber fabric, a fixed bed simulation corrosion experiment was used to study the corrosion behavior of 316 L alloy filter materials under SO_2 atmosphere, and analyze the filter performance and mechanical properties of the filter after corrosion. The influence of SO_2 concentration and flue gas components(O_2,H_2O) on its corrosion characteristics was studied. And the microscopic morphology and element distribution of the filter material before and after corrosion were combined to study the corrosion mechanism. The results show that the overall corrosion degree of the 316 L alloy fiber filter material is low, and the maximum corrosion gain rate during the corrosion cycle is 2.30 mg/g, which is mainly reflected in local corrosion. The enrichment of Mn and S elements is observed in the surface pits and the local content is 21.28% and 13.08%. The change of SO_2 concentration has a weak influence on the corrosion reaction, and the influence of O_2 on the corrosion process is mainly reflected in the oxidation reaction at the initial stage of corrosion, which has little promotion of the overall corrosion process. H_2O has a significant inhibitory effect on the corrosion reaction. The air permeability and pore structure stability of the filter material remain good after corrosion, the porosity decreases by less than 5%,while the flexural ratio of the material is significantly improved and vibration resistance is significantly reduced.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 29452K]

  • Research on the key influencing factors of ash wrapping of electrostatic precipitator in a 300 MW coal-fired unit

    HUANG Jianxun;XIE Yuxian;WANG Lele;SU Sheng;YIN Zijun;WANG Zhonghui;LEI Siyuan;XIANG Jun;Xiamen Huaxia International Power Development Co.,Ltd.;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;Suzhou Branch of Xi′an Thermal Power Research Institute Co.,Ltd.;

    Aiming at the serious ash wrapping and hardening of the electrode line of the electrostatic precipitator under the ultra-low emission condition of a 300 MW coal-fired unit in a power plant, the key influencing factors of the formation of ash wrapping on the pole wire of the electrostatic precipitator were studied by analyzing the loss on ignition, soluble ion concentration, ash composition, particle size and specific resistance characteristics of the ash deposited samples, combined with the ultra-low emission operation characteristics of the boiler. The results show that the content of NH■,SO■ and SO_3 in the ash-coated samples on the electrode wire of the low-temperature electrostatic precipitator are all higher, confirming that the main reason for the ash-coated sample of the electrostatic precipitator is the escape of ammonia from the SCR denitrification system and the combination with the ash. SO_3 in the flue gas reacts to generate ammonium hydrogen sulfate. Due to the low operating temperature of the low-low temperature electrostatic precipitator, it is difficult to decompose the ammonium hydrogen sulfate in the flue gas once it has formed, resulting in serious dusting of the electrode wire of the electrostatic precipitator. At the same time, due to the excessive humidity of the flue gas at the inlet of the precipitator, the viscosity of the fly ash increases, which aggravates the phenomenon of ash wrapping and hardening of the electrode wire of the electrostatic precipitator. Ammonium bisulfate changes the properties of fly ash and reduces the particle size of fly ash. At the same time, the adhesion of ammonium bisulfate affects the charging of the electrostatic precipitator, resulting in a decrease in the dust removal efficiency of the electrostatic precipitator and further aggravating the phenomenon of polar line ash deposition. Therefore, in order to reduce the phenomenon of dust wrapping and hardening of the electrostatic precipitator, it is necessary to effectively control the moisture content of the flue gas at the inlet of the electrostatic precipitator, and at the same time strictly control the key influencing factors such as ammonia escape and SO_3 generation concentration in the denitrification system.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 13215K]

  • Durability for solidified body of desulfurization wastewater from coal-fired power plants

    ZHENG Yangfan;HUANG Wenyao;DU Zhijian;QIAO Lin;QU Baozhong;WU Kai;MA Shuangchen;Guangdong Honghaiwan Power Generation Co.,Ltd.;Department of Environmental Science and Engineering,North China Electric Power University;

    Zero discharge of desulfurization wastewater is the key content of waste water management in thermal power plants. Cement solidification technology has potential as the final disposal means of zero discharge. The cement solidification technology has simple process, stable performance and wide application. In order to further optimize the application of cement immobilization technology in high concentration FGD wastewater treatment, durability research experiments were conducted based on the existing FGD wastewater flue gas concentration and cement curing technology. The compressive strength of the cured body was used as the basis for investigating the curing effect. Firstly, the curing body was made by mixing the FGD wastewater with cement, fly ash and river sand, and the compressive strength was tested after curing to a specific age. The orthogonal experiment was designed by controlling univariate method to investigate the effects of water-cement ratio, cement-ash ratio and river sand amount on the compressive strength of the cured body. The results show that the water-cement ratio has a significant effect on the compressive strength of concrete. The key to the selection of the curing composition ratio is the water-cement ratio, which leads to a decrease in the compressive strength of the cured body if the water-cement ratio increases. The water-cement ratio is controlled at 0.4-0.6. When the mud-cement ratio reaches 3.2∶1.0,the compressive strength performance of the cured body reaches the best state; and the change in the amount of river sand has less effect on the compressive strength of the cured body. At the same time, the leaching rate of heavy metal ions was analyzed to prove the feasibility of the curing method. The research provides basic data for the cement fixation of high salinity desulfurization wastewater.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 10307K]

  • Fault diagnosis of coal mill based on wavelet packet-LSTM neural network

    CHEN Bo;XU Wentao;HUANG Yaji;CAO Gehan;LI Yuxin;GUAN Shipian;WANG Ya′ou;Jiangsu Frontier Electric Technology Co.,Ltd.;Key Laboratory of Energy Thermal Conversion and Process Measurement and Control of Ministry of Education,Southeast University;

    As the most important equipment in pulverizing system of thermal power plant, the running state of coal mill directly affects the running performance of thermal power unit. Therefore, fault diagnosis of coal mill is of practical significance to ensure the safety of power plant production. Aiming at problems such as uncertain failure type and time lag in fault diagnosis during the actual operation of the coal mill, this paper proposed a fault diagnosis method for the coal mill based on wavelet packet-LSTM neural network. First, a prediction model for the outlet pressure and outlet temperature of the coal mill was established by utilizing the LSTM neural network. The normal data and fault data during the operation of the coal mill were combined into mixed data which be used as the input of the LSTM neural network prediction model to predict the outlet pressure and temperature of the coal mill and obtain the residual signa. Secondly, the wavelet packet decomposition method was used to distinguish and identify the sudden abnormal points of the residual signal. The correlation degree method was used to diagnose the fault types of coal mills by analyzing the trend of changes in all variables of partial data before and after the failure in the coal mill fault library and the mixed data. The results show that the average relative error of the outlet pressure and outlet temperature of the coal mill predicted by the LSTM neural network is not more than 1%. The Wavelet packet decomposition method is used for the residual signal, which can more accurately confirm the time point of the fault. The correlation coefficient method is used to analyze the change trend of all variables, which can identify the type of failure of the coal mill.

    2022 05 v.28;No.141 [PaperDigest][OnlineView][HTML全文][Download 11798K]
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