• CCUS technology development of coal-fired power plant under the background of Dual Carbon Strategy: Challenges and countermeasures

    MA Shuangchen;FAN Shuaijun;WU Kai;YANG Pengwei;CHEN Liutong;Department of Environmental Science and Engineering,North China Electric Power University;

    At present, coal power is still the main energy in China, with a large total installation capacity, which is difficult to be completely replaced in a short time. In the future, the technical standard for efficient and clean combustion of coal-fired power plants is low carbon emissions. At present, Dual Carbon Strategy has become a part of the construction of national ecological civilization, and coal power generation is in urgent need of carbon capture, utilization and storage(CCUS) technology suitable for future demand. However, in China, CCUS equipment has been put into operation in ultra-low emission power plants, and there are common problems such as high capture cost and limited utilization of products. CCUS technology with low development cost and effective utilization of captured products is a common demand for electric power environmental protection. To this end, the paper put forward coal power CCUS technology future development direction should be the integration of flue gas pollutants coupling control, such as the application of plasma oxidation technology, the first oxidation reducing pollutants SO_2 in flue gas, NO, etc., and then for ammonia absorber synergy desulfurization denitrification decarburization, overall pollutant removal process is simple, by-products has broad space for chemical conversion. Then, it is proposed that stable ammonia source supply can guarantee the implementation of the above integrated removal, and it is possible for coal power plants to provide more abundant product lines(ammonia energy, fertilizer, chemical products, etc.) in the future by building a self-sufficient ammonia production process.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 12972K]

  • Key technologies inventory of CO_2 geological utilization and storage

    WEI Ning;LIU Shengnan;LI Xiaochun;ZHANG Xian;JIA Guowei;WEI Feng;HU Yuanwu;State Key Laboratory for Geomechanics and Geo-Technical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences;The Administrative Centre for China′s Agenda 21;Wuhan Library,Chinese Academy of Sciences;

    CO_2 geological utilization and storage(CGUS) is essential to realizing large-scale low-carbon utilization and carbon neutrality of fossil-based energy and industries. In order to overcome the key technical difficulties of large-scale emission reduction of this technology, it is crucial to identify and evaluate key technologies and equipment for CO_2 geological utilization and storage. In this study, the various technologies of CGUS were defined and classified according to the expert panels and CGUS project investigations; and then the main characteristics and development trends of generic and special technologies were analyzed.The key technologies inventory was formed by the multiple criteria including unrepeatability, safety, efficiency, technical readiness levels(T_(RLs)) gaps, and the development potential.Moreover, the site characterization and monitoring technology were classified and analyzed according to multiple criteria methods; finally, some strategic recommendations on research and development activities were suggested. As a result, the key technologies at the primary technology level mainly focus on site characterization and screening, risk assessment and management, site monitoring and early warning, CO_2 utilization and resource treatment technology, synergies of carbon storage and resource recovery, etc. Although most of the technologies in China are at the stage of research and demonstration and the existing technology system can meet the requirement of large-scale CGUS projects; the significant technical gaps exist between T_(RLs) in China and international levels in various key technologies. Moreover, breakthroughs are necessary for these immature technologies globally before large-scale implementation of CGUS technology. Site monitoring technology is vital technology related to the security and effectiveness of CGUS,and there are considerable gaps between the current technology readiness levels and the requirements of large-scale CGUS projects, which needs to be further developed and verified to adapt to the CO_2 and reservoir environment, improve the long-term durability, monitoring accuracy, and the reliability of the interpretation of results. The key technologies requiring research and development include but are not limited to high-precision stratigraphic sequence exploration, high-precision seismic investigation technology, explanation of reservoir-seal pairs and lithology at ten-meter scales, assimilation technology of multiple data types and resolutions, site performance simulation and stratigraphic evaluation techniques, steering drilling & completion technology with related equipment, CO_2-resistant downhole and surface equipment, integration of site monitoring technology system, CO_2 geological storage risk prediction and risk management, underground space management and site performance assessment, collaborative optimization of carbon sequestration and resource recovery, etc. For the technical elements with large gap in technical maturity at home and abroad or highly dependent on imports such as high-precision sensors, CO_2 resistant sealing material, downhole reagents, new structures, new algorithms and codes, and sustained-release agents, it is necessary to improve the gold content and added value of elements and narrow the gap with the international technical level. In macro research, it is necessary to deploy fossil-based energy and industrial emission reduction strategies, industrial planning research, source and sink matching, CCUS and multi-industry integration strategy, etc. Therefore, it is necessary to improve the T_(RLs) of key technologies, improve the reliability and accuracy of existing technologies and technical elements, and ultimately set a solid foundation for core competitiveness in CGUS industrialization and commercialization.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 17414K]

  • Research progress of biomass blending technology in pulverized coal furnace for power generation

    ZHOU Yi;ZHANG Shouyu;LANG Sen;LIU Simeng;YANG Jifan;MA Dafu;HU Nan;WU Yuxin;School of Energy and Power Engineering,University of Shanghai for Science and Technology;Changchun Institute of Technology;Department of Thermal Engineering,Tsinghua University;

    Under the pressure of carbon peak and carbon neutralization emission reduction, biomass has attracted much attention due to its characteristics of wide source, abundant reserves, clean and low-carbon emissions. There are many kinds of biomass, including straw, forestry waste, livestock manure, domestic waste and waste oil. Biomass blending in coal-fired power plants can effectively reduce carbon dioxide emissions and strengthen the flexibility transformation of boiler fuel side. The characteristics of biomass were introduced, and the characteristics of combustion, slagging and pollutant emissions of biomass blending in pulverized were summarized. The technical routes and transformation cost of biomass blending in pulverized coal boiler were summarized and compared. Lastly, the technical barriers and solutions to co-combustion of biomass in pulverized coal boiler were discussed. Agroforestry biomass has high volatiles and good reactivity. Blending this kind of biomass can improve the fuel combustion performance and increase the combustion stability of the boiler. However, the alkali metal content in biomass is high, and it is easy to cause serious slagging when blending. The ash melting temperature and alkali metal content in fuel are important indicators for predicting boiler slagging. The sulfur content, nitrogen content, ash content and heavy metal content of agricultural and forestry biomass are low. The combustion of blending biomass can reduce SO_x,NO_x,soot and heavy metal emission. Sludge biomass has high moisture content, high heavy metal content, low calorific value, and less combustion characteristics than coal, so it is usually to have a bad influence on combustion and pollutant emission, but the direct blending sludge below 10%(mass ratio) has little effect on the unit. The biomass gas generated from the gasification of livestock manure, domestic waste and waste oil can play a role in stabilizing combustion in pulverized coal furnace and reduce SO_x,NO_x,soot and heavy metal emissions. The direct coupling scheme of biomass and coal coupling power generation technology is more suitable for the co-combustion of agricultural and forestry waste. The indirect coupling co-combustion is more suitable for the co-combustion of livestock manure and domestic waste, while sludge co-combustion needs to be dried. It is believed that the compressive strength and energy density of molded fuel made of biomass after compression molding are greatly improved, and this technology can solve the supply chain problems such as biomass storage and transportation. Fuel pretreatment and anti-slagging additives can reduce alkali metal content of biomass, improve ash melting temperature and reduce the risk of boiler slagging. Baking treatment can improve the grindability of biomass, increase the proportion of biomass blending, and improve the adaptability of boiler pulverizing system to biomass blending. The modification of boiler burners and reasonable air distribution can improve the adaptability of combustion system to mixed burning biomass. The acquisition cost of agricultural and forestry biomass raw materials is higher than that of coal, and inaccurate measurement of biomass power generation can not get financial support, the economy is poor. The economy of co-firing biomass is the main reason that hinders the large-scale co-firing of biomass. The measurement of low-cost biomass sources and biomass power generation needs to be solved urgently.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 7894K]

  • Potential analysis of coal-biomass co-firing power generation in China based on a spatial analysis method

    ZHENG Dingqian;TIAN Shanjun;MA Sining;CHANG Shiyan;Tsinghua University-University of Alberta Joint Research Center for Future Energy and Environment,Tsinghua University;School of Information Science and Engineering,Shandong Normal University;Institute of Energy,Environment and Economy,Tsinghua University;Tsinghua University-China Three Gorges Corporation Joint Research Center for Climate Governance Mechanism and Green Low-carbon Transformation Strategy,Tsinghua University;Tsinghua-Rio Tinto Join

    Coal-biomass co-firing power generation(CBCP) can reduce CO_2 emissions and alleviate air pollution. Considering the low energy density of straw resources, the application potential of coal-fired coupled biomass power generation technology largely depends on the spatial matching between coal-fired power plants and straw resources. Therefore, from the perspective of spatial analysis, it is of great significance to study the potential of coal-fired coupled biomass power generation. The possible potential of coal-fired coupled power generation was evaluated by spatial matching method based on high-resolution coal-fired power plants and straw resource data. The research results show that coal-fired power plants are highly spatial matched with straw resources in China, with about 89% of the collectible straw located within a 100 km radius of coal-fired power plants. The amount of co-fired straw in coal-fired power plants is affected by the energy utilization ratio of straw and the co-firing level of straw in power plants. The higher the energy utilization of straw is and the higher the co-firing level in power plants is, the more straw is that can be co-firing in coal-fired power plants. Under the scenario of the high energy utilization rate of straw and 30% co-firing level, 1 066 power plants can find straw resources within a radius of 100 km, of which 52.6% of power plants can meet the 30% co-firing level. In this scenario, the power plant can absorb 384 million ton of straw and reduce CO_2 by about 511 million ton. The results can provide technical support for the formulation of technical support policies for coal-biomass co-firing power generation and straw resource utilization policies in China.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 13184K]

  • Co-combustion and sulfur oxide release characteristics of typical sludge and coal slime

    WANG Xin;LING Peng;AN Xiaoxue;HAN Hengda;XU Jun;JIANG Long;WANG Yi;SU Sheng;HU Song;XIANG Jun;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;

    The output of sludge and coal slime is increasing year by year, which affects the ecological environment and human life, and it is urgent to deal with them reasonably. Combined with the respective fuel characteristics of sludge and coal slime, the co-combustion of the two can produce a certain synergistic effect and form an effective complementarity in different combustion stages, and finally realize the efficient co-combustion and comprehensive reduction of the two, which is of great significance for the efficient disposal of sludge and coal slime. The co-combustion characteristics and sulfur oxide release characteristics of sludge/coal slime and typical fuels(coal, biomass, etc.) have been studied, but there are few studies on the co-combustion characteristics and sulfur oxide release characteristics between the two. Therefore, on the self-built fixed-bed combustion reaction system, the co-combustion experiments were carried out on a typical dried sludge(Dali sludge) and two types of coal slimes(Lingshi coal slime and Shanxi coking coal slime) after drying. The influence mechanism of fuel type, temperature, mixing ratio and other factors on co-combustion characteristics and sulfur oxide release characteristics was analyzed. The results show that the combustion reaction can be accelerated by increasing the temperature and sludge mixing ratio when sludge and coal slime are mixed for combustion. During the combustion process, the conversion rate of SO_2 firstly decreases and then increases with the increase of combustion temperature. High temperature can promote the secondary release of sulfur fixed in inorganic matter. There is an obvious interaction in the co-combustion of sludge and coal slime, which will significantly affect the generation and release of SO_2. At 800 ℃,the sulfur fixation is strengthened and the release of SO_2 is inhibited due to the formation of sulfur-containing compounds between ash and SO_2. However, when burning at 1 000 ℃,the decomposition of inorganic sulfur is accelerated due to the accelerated combustion reaction, which leads to the increase of SO_2 release. The experimental results show that the combustion with 30% sludge/70% coal slime mixture at 800 ℃ can achieve lower SO_2 emission and higher fuel burnout characteristics.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 36812K]

  • Influence of large-scale coupled hydrogen derived fuel power generation on coal-fired units

    WANG Yikun;DENG Lei;CHEN Gang;ZHOU Fei;JIA Zhaopeng;ZHANG Zhida;TANG Yanfeng;Xi′an Thermal Power Research Institute Co.,Ltd.;State Key Laboratory of Multiphase Flow in Power Engineering,Xi′an Jiaotong University;Huaneng Taicang Power Plant Co.,Ltd.;

    As a solution for large-scale utilization of hydrogen energy, hydrogen derived fuel has attracted much attention in recent years. Coupling hydrogen derived fuel power generation can greatly reduce carbon emissions of coal-fired units, which is expected to become an important way for coal-fired units to achieve carbon emission reduction in the future. The thermal calculation was performed on a 300 MW coal-fired unit. The influence of coupled hydrogen derived fuel power generation(mass ratios of 0-100%) on various systems and operating parameters of the unit under different working conditions were analyzed under different working conditions in this paper. The results show that the maximum annual emission reduction is about 1.212 million tons of CO_2 after large-scale coupling of hydrogen derived fuel. The variation of unit parameters is related to the characteristics of hydrogen-based derived fuel. When the calorific value of hydrogen derived fuel is high, the exhaust temperature decreases by 2.7-9.2 ℃,the boiler thermal efficiency increases by 0.04-0.91 percent point, and the flue gas mass decreases by 20.1-20.8 percent point. When the calorific value of hydrogen derived fuel is low, the exhaust temperature rises by 2.4-26.2 ℃,the boiler thermal efficiency decreases by 0.18-2.04 percent point, and the maximum increase of flue gas mass is 0.4%. Coupling hydrogen derived fuel has little influence on the original air supply system, denitration and desulfurization system. The induced draft fan needs to be expanded and reconstructed. It is necessary to add the independent combustion system and improve the protection level of field equipment and develop the new capture system to reduce emissions of unconventional pollutants such as secondary organic aerosol, formaldehyde and aldehyde.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 41136K]

  • Hot temperature corrosion performance of Inconel 625 coating prepared by ultra-high speed laser cladding technique in biomass boiler

    ZHANG Lan;SUN Jinyu;HUANG Xinhe;LUO Xiaotao;DENG Shuanghui;WANG Xuebin;The Boiler & Pressure Vessel Safety Inspection Institute of Henan Province;Nandian Synthesis Energy Utilization Co.,Ltd.;School of Materials Science and Engineering,Xi′an Jiaotong University;School of Energy and Engineering,Xi′an Jiaotong University;

    To alleviate the hot temperature corrosion problem for the heated side pipe from the biomass incineration, and achieve the purpose of long-term pure burning/blending of biomass in the boiler, the Inconel 625 alloy coating has been prepared on TP347 substrate by ultra-high speed laser cladding technique. The microstructure and elemental segregation of the cladding layer were characterized by SEM and EDS;a self-made hot temperature corrosion setup was used to simulate the real environment of biomass incineration, and the hot temperature corrosion properties of TP347 and Inconel 625 coating were comparatively tested at 550 ℃. The results show that the optimized ultra-high speed laser cladding Inconel 625 coating has no obvious defects and forms a good metallurgical bonding interface with TP347 steel substrate. The coating is composed of fine γ-Ni phase and the precipitate on the boundary, and the hardness reaches HV341. There′s barely elemental segregation inside the coating, and the concentrations of Ni, Cr show little decrease for the bondary precipitate. For two samples, the corrosion weight gain increases linearly with the corrosion time. The weight gain of Inconel 625 coating is only 1/62 of the TP347 steel at 550 ℃ for 500 h, mainly due to its low Fe content and uniform corrosion characteristics at the interface. The Inconel 625 coating by ultra-high speed laser cladding can effectively improve the corrosion resistance of the heated side pipe in biomass incineration boiler.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 37098K]

  • Research progress on co-pyrolysis of biomass and oil shale

    ZHAI Yingmei;ZHU Yiming;YANG Tianhua;College of Energy and Environment,Shenyang Aerospace University;

    Co-pyrolysis of biomass and oil shale to produce oil can solve the problems of low shale oil yield and high oxygen content of bio-oil, which considered both oil yield and quality with a positive synergy. The co-pyrolysis oil with high economy can be used as an alternative energy source for petroleum after refining, and further alleviate the oil shortage in China. Based on the above background, the research progress on co-pyrolysis of biomass and oil shale was reviewed. Firstly, the pyrolysis characteristics of oil shale and biomass were discussed, respectively. Then the effects of biomass raw materials and pyrolysis temperature on the co-pyrolysis process and product characteristics were clarified, especially the significant effect of secondary reactions on product distribution due to the excessive pyrolysis temperature. On this basis, the free radical release-binding mechanism, five alkali/alkaline earth metal catalytic mechanisms and various types of mineral catalytic mechanism were summarized. The synergy mechanism were explained as a result of the combination of free radicals and the multiple catalytic behavior. Finally, based on the research status, the future prospects of biomass-oil shale co-pyrolysis were proposed from several aspects including new experimental equipment, micro mechanism and numerical modelling study.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 1858K]

  • Application of coal-based graphene for lithium-ion batteries

    PAN Qiang;GU Xiaohu;LIN Xiongchao;MA Mingjie;Coking Coal Resources Development and Utilization State Key Laboratory,China Pingmei Shenma Group;School of Chemical and Environmental Engineering,China University of Mining and Technology-Beijing;College of Chemistry and Chemical Engineering,Henan Polytechnic University;

    High value-added graphene with high tap density and crumpled texture could be produced from coal via various physical or chemical methods. However, the technological process is complex, purification of deashing, catalytic graphitization, oxidation-reduction and CVD need to be promoted. Graphene, as a novel carbon nanomaterial, possesses unique properties, such as high electrical conductivity, high thermal conductivity, large specific surface area and stable mechanical properties. Coal-based graphene has very broad application prospects in lithium-ion batteries. The application and latest research achievements of graphene in lithium-ion batteries was reviewed. The modification of anode and cathode of batteries by graphene and the preparation of graphene composite conductive agent were focused. A conductive network with a "surface-point" and "point-point" contact mode could be constructed by graphene and different spatial spans could be formed with active materials and conventional conductive agents. Formation of efficient and stable conductive networks around the active materials from different spatial spans, while taking advantage of the unique characteristics of each material. In addition, it can suppress the effect of volumetric expansion, and stabilize the structure, which can improve the specific capacity, charge-discharge properties, cycle performance, rate capability and heat dissipation performance of the whole system. It can also improve the heat dissipation performance of the battery system and increase the upper limit of service temperature, which has obvious advantages compared with the traditional carbon material. The molecular structure, elemental composition, mineral content, maceral components, and degree of metamorphism of coal would affect the characteristics of coal-based graphene. Products with high graphitization degree could be produced from high degree of coal meta-morphism, which had large crystallite dimension and few layer. Graphitizing and particle size is more stringent with using lignite coal and bituminous coal as raw materials. For lithium-ion battery applications, the approach of graphene based coal should use direct oxidation-reduction with high degree of coal. The raw material is mainly anthracite coal with deeper metamorphism, which can generate graphene with higher graphitization, larger microcrystal size and fewer lamellae. And there are a few defects and carbon vacancy by removing oxygen element which could provide extra storage points in the charging process of lithium batteries and increase the reversible capacity. It is important to enhance pretreatment research which could improve basic structural units of coal and aromatic structure. Organic polycyclic aromatic hydrocarbons are easily transformed to layered graphite structure which is good for oxide intercalated. In the conventional battery system, directly using graphene as the anode of lithium-ion battery had the disadvantages of voltage lag and low coulomb efficiency. It is necessary to further elucidate the microscopic changes of graphene in the process of lithium inserting and extracting. In addition, the electrode thickness, size distribution, surface properties, functional groups, layer number, and lamellar structure of graphene would affect its advantages.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 11704K]

  • Review on photocatalytic CO_2 reduction reaction

    TONG Zhenwei;ZHONG Zhencheng;National Institute of Clean and-Low-Carbon Energy;

    Aimed at obtaining economically valuable fuels or chemicals, the chemical conversion of CO_2 provides a renewable utilization route for CO_2,which is one of the most promising alternatives to solve current carbon emission issue and achieve CO_2 neutrality. Compared with traditional thermocatalysis, photocatalytic technology has the advantages of low energy consumption and mild reaction conditions, and is one of the ideal solutions to realize the energy utilization of CO_2. However, owing to the chemical stability of CO_2,the conversion reactions that convert CO_2 are relatively low. The research core of photocatalytic CO_2 reduction is to improve the catalytic activity of photocatalysts through the design of catalyst and reaction system so as to improve the selectivity and controllability of the CO_2 reduction products. Due to the urgency of photocatalytic CO_2 conversion technology at the present stage, a timely and comprehensive understanding of the research progress in this field in recent years is helpful to reasonably analyze the possible research direction in the next stage. The research progress of photocatalytic CO_2 reduction was reviewed from the advantages of photocatalysis, reaction mechanism, catalysts and the latest research results. The composition of the photocatalysis system, the electron reduction process of CO_2,and the current products of CO_2 photocatalytic conversion, yield, scale and factors affecting the selectivity of products were described in detail. The strategies to improve the reduction performance were mainly elaborated, including the introduction of noble metals co-catalysts, the construction of heterojunction structure, exploring new photocatalysts, the construction of electron transport channel and coupling of electric or thermal catalysis with photocatalysis, etc. The results show that the above strategies can improve the conversion rate of CO_2 reduction reaction in varying degrees, and the types of reduction products gradually develop from C_1 to C_2. Notably, photoelectric/photothermal catalysis has a higher conversion rate than photocatalysis alone, which improves the possibility of future application of this technology and deserves much research and attention. In addition, it is pointed out that the current photocatalytic reduction of CO_2 has problems of insufficient conversion efficiency, poor product selectivity, and unable to achieve controllable synthesis of high value-added products, etc. Future research should focus on the development of high-efficiency photocatalysts and the catalytic kinetics.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 17586K]

  • Effect of internal minerals on supercritical liquefaction of oil shale

    TONG Bolin;YANG Tianhua;LI Bingshuo;ZHAI Yingmei;College of Energy and Environment,Shenyang Aerospace University;

    Oil shale is a kind of non-traditional primary energy with organic matter structure similar to that of coal. High mineral content in oil shale is one of the main reasons why it can not be used efficiently. As a new method of heat treatment, supercritical liquefaction is widely used in the research of coal and biomass utilization and structure, but it is less utilized in oil shale. Fushun oil shale was treated by HCl and HF acid elution to obtain demineralized oil shale.Supercritical liquefaction experiments of crude oil shale and demineralized oil shale were carried out in a high temperature and high pressure batch reactor with ethanol as solvent to explore the effects of internal carbonate and silicate on the characteristics of liquefaction products. XRF and XRD results show that the minerals in Fushun oil shale are mainly silica-aluminates. The increase of liquefaction temperature has a promoting effect on the shale oil yield. At 360 ℃, the yields of shale oil prepared by the original sample and demineralized oil shale reaches the highest value. The yields of shale oil from original sample, decarbonate sample and desilicate sample are 53.8%, 56.9% and 42.8% at 360 ℃, respectively, which are increased by 33.4%, 37.8% and 29.3% than those of 300 ℃. Alkali metal and alkaline earth metal cations in carbonate inhibit the formation of alkanes. Silicate promotes the formation of low carbon number hydrocarbon through acid sites. Carbonate promotes the formation of ethyl fatty acid, whereas silicate has the opposite effect. The oxygen-containing weak bond and C—C bond of fat structure are broken during supercritical liquefaction. These two types of broken bonds form small molecules as organic sources of shale oil.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 18118K]

  • Performance of Ag/AgCl modified Bi_5O_7I/Bi_2O_3 composite for photocatalytic oxidation of elemental mercury

    SHI Lei;ZHANG Anchao;ZHANG Huige;ZHANG Qianqian;ZHENG Hongxiang;ZHANG Xu;ZHANG Jingfan;School of Mechanical and Power Engineering,Henan Polytechnic University;

    Mercury possesses the characteristics of hypertoxicity, atmospheric migration and bioaccumulation, which has posed a serious threat to the ecological environment and human health. The mercury emission in China from coal combustion ranks first in the world, therefore, it is imperative to strengthen the research on mercury control technology. It is the key to control mercury pollution by the efficient oxidation of elemental mercury(Hg~0) from coal-fired flue gas. Using Ag/AgCl modified Bi_5O_7I/Bi_2O_3 composite as photocatalyst, the effects of experimental parameters such as Ag/Bi mass ratio, pH, inorganic anion, SO_2 and NO on the removal of gaseous elemental mercury by photocatalyst were studied in a wet photocatalytic reactor. The photocatalysts were characterized by N_2 adsorption-desorption, XRD,SEM,DRS,XPS and ESR. The results show that Ag/AgCl modified Bi_5O_7I/Bi_2O_3 composite possesses the superior photocatalytic oxidation performance and the mercury removal efficiency can reach as high as 98.5% when the Ag/Bi mass ratio is 0.03. With the increase of pH and the addition of inorganic carbonate ions, the efficiency of mercury removal decreases significantly. Compared with NO,SO_2 has a greater inhibitory effect on gaseous Hg~0 removal. The chemical species of Bi and O in Bi_5O_7I/Bi_2O_3 will be varied due to the addition of Ag/AgCl, and a Z-scheme heterojunction structure is formed between Ag/AgCl and Bi_5O_7I/Bi_2O_3,which plays a crucial role in the activity of quaternary composite photocatalytic materials. The experiments of free radical capture show that superoxide radical(·O~-_2) and holes(h~+) were the main active substances for Hg~0 removal.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 34739K]

  • Preparation of activated carbon from licorice by hydrothermal carbonization and chemical activation

    HE Ziqian;ZHOU Yabin;ZHANG Cheng;TAN Peng;FANG Qingyan;CHEN Gang;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;

    Licorice is the main component of traditional Chinese medicine prescriptions, and the amount of licorice residue produced has gradually increased with the development of the traditional Chinese medicine industry. However, the utilization of licorice residue is not ideal. Licorice contains a large amount of cellulose, hemicellulose and lignin, which is an excellent raw material for the preparation of activated carbon. The technical route of combined hydrothermal carbonization and chemical activation to prepare activated carbon can better pretreat the licorice residue with high water content, and conduct chemical activation to prepare activated carbon, which is an excellent way for efficient utilization of licorice residue. Using licorice as raw material, licorice was mixed with deionized water at a mass ratio of a ratio of 1∶8, and then hydrothermally carbonized at 210, 240, 270, and 300 ℃ respectively.And the hydrothermal carbon obtained by the hydrothermal carbonization reaction at 270 ℃ was activated with different chemical activators and at different activation temperatures, respectively. The results show that the sample has obvious functional group changes at 270 ℃, and it is believed that carbonization has occurred at 270 ℃. The activated carbon prepared by the combination of hydrothermal carbonization and chemical activation has a good pore structure.With KOH as a chemical activator, the activated carbon prepared under the condition of activation temperature of 700 ℃ has a specific surface area of 1 605.77 m~2/g, a total pore volume of 0.890 4 cm~3/g, an average pore size of 2.218 0 nm, and a methyl orange adsorption capacity of 184.5 mg/g.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 16524K]

  • Technical and economic evaluation of low carbon development path of typical coal chemical projects

    KE Yan;TAO Yi;YI Xuerui;BU Xuepeng;WANG Qiang;Guoneng Economic and Technological Research Institute Co.,Ltd.;

    The Double Carbon goal is China′s solemn commitment to the world. Coal chemical industry belongs to the high carbon emissionclass industry. It is urgent to explore the low-carbon development path. Based on the carbon trading price of 100 yuan/ton and the outsourcing proportion of carbon trading of 5%, 20% and 50% as three scenarios, this paper analyzed the technical economy of low-carbon paths such as energy conservation and emission reduction, green hydrogen substitution, green electricity substitution, low-carbon raw materials, product scheme optimization and end use of carbon dioxide, respectively. The analysis shows that the cost change per unit product of green electricity plus electric drive scheme is small, which is a more economical and reasonable low-carbon scheme. At present, it is recommended to give priority to the green power on drive scheme. The second is the energy conservation and emission reduction scheme, which should be optimized in the early stage of the project. Product scheme optimization is also an effective way to reduce emission and increase efficiency. It is suggested to develop oxygenated compounds and other products suitable for coal chemical process, but the cost needs to be further reduced through technological innovation. Due to the high price of green electricity and poor economy, the green hydrogen scheme can be firstly used as the pilot of reserve technology. The raw material low-carbon scheme depends on the reliability of natural gas supply and national policies. At present, the economy of carbon dioxide end-use is poor. It is suggested to further demonstrate the utilization paths such as CCUS to improve the overall economic benefits.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 3271K]

  • Emissions and flow field studies of swirl premixed flames stabilized using displacement bluff-body

    HAN Delin;WANG Tiantian;ZOU Jun;ZHANG Hai;ZHANG Yang;LYU Junfu;WANG Suilin;School of Environment and Energy Engineering,Beijing University of Civil Engineering and Architecture;Department of Energy and Power Engineering,Tsinghua University;Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Department of Energy and Power Engineering,Tsinghua University;

    In a π-type boiler, the low NO_x coal-to-gas transition may result in the problems of the "wall brush" of the flame torch and carbon deposition, and the swirl premixed combustion method is attractive as it provides short flame length and fast burn-out. Combining the advantages of both lean premixed swirl combustion and bluff-body combustion, a lean premixed swirl burner integrated with a displacement bluff-body was designed. By moving the position of the bluff-body, the burner outlet flow velocity could be tuned. The swirl premixed flames pollutant generation characteristics under different swirl numbers, thermal power and bluff-body position conditions were studied and the flow field at the outlet of the burner nozzle was measured using particle image velocimetry technology. Results show that the amount of NO_x generated first decreases and then increases with the increase of the swirl number, the NO_x concentration is lowest at the swirl number of 0.25. When the bluff-body height is fixed, since the flow velocity increases with the increase of thermal power at this time, the NO_x concentration decreases while the CO concentration increases as a function of the thermal power. If the bluff-body position is varied to keep a fixed outlet flow velocity, both the NO_x and CO concentrations are maintained at a relatively low level, as NO_x<12 mg/m~3,CO<7 mg/m~3,and only a small amount of CO is generated at the lowest thermal power. Based on the flow field and flame analysis, as the swirl number increases from 0 to 0.25,the flame width increases, strengthening the flue gas entrainment, and resulting in a decrease in the NO_x emission. As the swirl number further increases from 0.25 to 0.83,the width of the flame hardly changes but the axial flue gas recirculation is enhanced, increasing the residence time of the hot flue gas and the NO_x formation. Therefore, optimized bluff body position and swirl number lead to a reasonable flow field and flame structure, and thereby keep the emissions at a relatively low level.

    2022 06 [PaperDigest][OnlineView][HTML全文][Download 17652K]

  • Combustion performance of a semi-coke fired circulating fluidized bed boiler based on CFB model

    LI Jingyuan;KE Xiwei;JIANG Ling;HUANG Zhong;ZHANG Man;Department of Energy and Power Engineering,Tsinghua University;

    Semi-coke has the characteristics of low volatile matter and high fixed carbon. Compared with pulverized coal boiler, circulating fluidized bed(CFB) boiler is more suitable for semi-coke combustion. In order to understand the combustion performance of the circulating fluidized bed boiler for semi-coke, the one-dimensional circulating fluidized bed boiler model was used to simulate a CFB boiler for semi-coke. By comparing the model prediction of particle size distribution of circulating ash and bottom slag with the measurement results of field sampling, the two match well and verify the reasonableness and accuracy of the overall boiler model. Through simulation, the effects of cyclone efficiency and semi-coke particle size on semi-coke CFB boiler were analyzed. The simulation results show that the cyclone efficiency has a very significant impact on the performance of semi-coke fired circulating fluidized bed. Improving the cyclone efficiency can increase combustion efficiency of semi-coke, and median particle size of fly ash is recommended to be controlled around 10 μm.Feed coal particle size has an important effect on the CFB boiler of semi-coke. The combustion efficiency is decreased by reducing the semi-coke particle size, and NO_x emission can be reduced significantly.According to the ash formation characteristics of semi-coke, the inject particle size should be in the range of 0.5-6.0 mm.Comparing with the circulating fluidized bed boiler burning lignite, the temperature in the furnace is higher when burns semi-coke, and the combustion efficiency is lower. Both SO_2 emission and NO_x emissions in the combustion process of semi-coke are low, but it still needs flue gas denitrification systems to meet the pollutant emissions. All above results provide a direction for the operation optimization of CFB boiler that fires semi-coke.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 13005K]

  • Numerical simulation of flow field and combustion characteristics of DRB-4Z swirl pulverized coal burner

    HU Yaohui;PENG Zhimin;LI Yonghua;Department of Power Engineering,North China Electric Power University;Department of Energy and Power Engineering,Tsinghua University;

    At present, hedge boilers are widely used in large capacity units, and the combustion effect of hedge boilers depends on the performance of burners. In order to analyze the flow and combustion characteristics of DRB-4 Z swirl pulverized coal burner, the flow field distribution of a single burner and the combustion process of a 1 000 MW ultra supercritical unit(using DRB-4 Z swirl pulverized coal burner)were simulated by Fluent software. The effects of primary air speed, internal and external secondary air speed and swirl intensity on primary air stiffness, location and range of reflux area were studied. The flow field simulation results of a single burner show that the primary air velocity of DRB-4 Z swirl pulverized coal burner is inversely proportional to the range of reflux area. When the primary air velocity is 16 m/s under rated load, the flow field distribution is better. The primary air velocity under low load should not be less than 12 m/s, so as to avoid the ignition point of pulverized coal being too close to the burner outlet, and the primary air velocity under high load should not exceed 20 m/s, so as to ensure that pulverized coal gets sufficient heat at the initial stage of combustion, the wind speed of internal and external secondary air is directly proportional to the range of reflux area, when the wind speed of internal secondary air is 28 m/s and the swirl intensity is 0.75,the flow field distribution is good. For combustible coal, the opening of internal secondary air blade can be set to 30°,and the swirl intensity is 0.52,so as to delay the mixing of primary air and internal secondary air and reduce the generation of NO_x. For difficult coal combustion, the opening of secondary air blade in the seed can be set to 50°,and the swirl intensity is 1.02 to ensure that enough high-temperature flue gas is entrained in the reflux area to make the stable combustion of pulverized coal. The simulation results of boiler combustion process show that the temperature in the middle and upper burner area of the furnace is the highest, and the maximum temperature can reach 1 900 K. The main combustion area is in a state of severe hypoxia. Although severe hypoxia in the main combustion area can reduce the generation of NO_x,a large number of reducing gases CO and H_2S are generated in the outlet area of the burner, which is easy to cause high-temperature corrosion of the water wall.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 33678K]

  • Flow field optimization of SCR-DeNO_x system in a 300 MW coal-fired power plant

    HUANG Jun;LI Xinglei;RUAN Bin;LUO Sheng;LU Zhimin;YAO Shunchun;Guangzhou Zhujiang Electric Power Co.,Ltd.;School of Electric Power,South China University of Technology;Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization;Guangdong Province Engineering Research Center of High Efficiency and Low Pollution Energy Conversion;

    Under the requirements of ultra-low emission, the excessive injection of ammonia in the SCR DeNO_x reactor not only affects the economy, but has also causes a series of operation and maintenance problems such as air preheater blockage, electrostatic precipitator fouling, and bag paste. In order to improve the uniformity of SCR inlet flue gas velocity and ammonia-nitrogen molar ratio, the computational fluid dynamics simulation and optimization research of flue flow field on one side SCR reactor of an old 300 MW unit in a certain power plant were carried out. Using Fluent as the main tool and based on the analysis of the empty tower model and the original deflector arrangement, the SCR flue deflector structure was optimized, and a static mixer was arranged downstream of the ammonia injection grid to achieve uniform cross-sectional velocity and ammonia-nitrogen molar ratio in the first layer of catalyst. The relative standard deviation of the velocity of the empty tower scheme is 26.1%,and the relative standard deviation of the ammonia-nitrogen molar ratio is 24.8%,all of which can not meet the engineering design requirements. In the original scheme, six groups of deflectors are set at the gradual expansion and corner of SCR flue, and the uniformity of speed and concentration is greatly improved, the relative standard deviation of the speed is 13.9%,which can meet the engineering design requirements, while the relative standard deviation of the ammonia nitrogen molar ratio is 15.3%,which can not meet the design requirements of less than 10%. The flow deflector arranged in the optimized scheme eliminates the vortex and reflux of flue gas at the flue corner and gradual expansion. Meanwhile, the static mixer is installed to enhance mixing, so that the relative standard deviation of velocity is reduced to 11.4%,and the relative standard of ammonia-nitrogen molar ratio to 9.4%. The uniformity of the flow field in the SCR flue has been greatly improved and the speed and concentration uniformity meet the design requirements. At the same time, the pressure loss of the optimized scheme is 706 Pa, which meets the B-level design requirements. The results show that the reasonable arrangement of the baffle and static mixer can improve the uniformity of the flow field without causing excessive pressure loss. The present work has reference value for the optimization of the on-site SCR flow field retrofit.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 15341K]

  • Pressure drop characteristics of large particle ash interceptor in SCR flue gas denitrification system

    MENG Lei;LEI Yu;CHEN Sheng;LIU Xiaowei;YUE Pujie;GU Xiaobing;Datang Environment Industry Group Co.,Ltd.;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;

    The large ash particles in the flue gas from coal combustion would lead to severe blockage and wear problems of the catalyst in a selective catalytic reduction(SCR)denitrification system, which affects the service life and denitration performance of SCR catalyst. This problem can be effectively solved by installing an interception net device in the flue to intercept large particle ash. The design of interceptor mainly depends on experimental measurement and engineering experience, which lacks general design criteria and theoretical basis, and the research on influence factors of pressure drop is not deeply explored. It is of significance for developing an effective and low-cost interceptor to calculate accurately the pressure drop of the flow across the interceptor with different pore structures. The influences of pore structure, flue gas velocity, interceptor porosity and thickness on the pressure drop were investigated based on computational fluid dynamics by construct the calculation model of interceptor mesh. The simulation results show that controlling parameters on pressure drop are the flow velocity and the porosity. The pressure drop is a quadratic power function of the flow velocity within the range of 5-20 m/s and inversely proportional to the third power of the porosity when the porosity of the interception network is 40%-65%. It is also found that, given the same porosity, the pore structure has negligible effect on the pressure drop. And the strip interceptor has the minimum pressure drop under the condition of the same critical size. The pressure drop increases quasi-linearly with the thickness of interceptor increase in the range 6-18 mm. Based on a large number of simulation data, A correlation is then proposed to predict the pressure drop and the empirical expression of the equivalent porous medium permeability of the interception network is further deduced, which can be feasibly applied to full-scale CFD simulation of SCR denitrification system.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 8235K]

  • Design and analysis of thermal zero discharge for flue gas desulfurization wastewater of coal-fired power plants

    AN Xuefeng;LIU Guangjian;CHEN Haiping;School of Energy Power and Mechanical Engineering,North China Electric Power University;

    With the continuous improvement of China′s environmental protection policies and the serious lack of water resources, the deep treatment of flue gas desulfurization(FGD) wastewater and water recovery are of great significance. In the present work, an overall zero liquid discharge(ZLD) process system for FGD wastewater was constructed, and three kinds of thermal concentration processes were proposed: multi-effect evaporation system(MEE),single stage mechanical vapor recompression system(MVR-S) and multi-effect evaporation system coupled with MVR(MEE-MVR). MEE includes multi-effect evaporation system driven by live steam and multi-effect evaporction system driven by low-temperature flue gas.Taking a 600 MW supercritical unit as an example, process simulation and system economics calculation were carried out using Aspen Plus software.The results show that compared with the traditional multi-effect evaporation system driven by live steam(MEE-S),the temperature of the flue gas is reduced by 5.5 ℃ when the low-temperature flue gas is used as the heat source. If the cost of the low-temperature flue gas is ignored, the cost of wastewater treatment per ton is lowest. The energy consumption of single-stage MVR system is greatly reduced due to the use of heat pump evaporation technology, but the investment cost is 113% of MEE-S system. For the MEE-MVR system, the power consumption of the compressor is reduced by 30% compared with the MVR-S,and the cost of wastewater treatment per ton is about 58.2% of the MEE-S system.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 20024K]

  • Experimental study on ultrasonic-assisted leaching of biomass fly ash

    HAN Kuihua;LIU Wenyang;SONG Chuanlin;REN Ke;TENG Zhaocai;NIU Shengli;WANG Yongzheng;ZHU Yingquan;LONG Shenwei;School of Energy and Power Engineering,Shandong University;Shandong Engineering Laboratory for High-efficiency Energy Conservation and Energy Storage Technology & Equipment,Shandong University;Shandong Fengyuan Biomass Power Generation Co.,Ltd.;

    The fly ash produced from biomass power generation boilers is generally used as building materials and auxiliary materials for fertilizer production. However, the hazardous components in fly ash can reduce the stability of building materials and cause the enrichment of heavy metals in farmland. Therefore, the pretreatment of fly ash raw materials and the improvement of suitability are the key issues. In this study, fly ash from biomass power plant was used as raw material to obtain fine ash with particle size <0.2 mm by sieving. Fine ash and deionized water were prepared into slurry, which was treated by ultrasonic-assisted leaching and filtration. The effects of sonication time, slurry temperature, solid-liquid mass ratio on the leaching of macroscopic metal elements K,Na, Zn, Ca, and four trace heavy metal elements Co, Cr, Ni, Pb were investigated. The appropriate operating parameters were explored. The results show that the fine ash used in the experiment is rich in CaO,SiO_2 and K_2O. For macroscopic metal elements, the leaching concentration and leaching amount of metal elements increase and tend to be constant with the time prolonging within 1-30 minutes of sonication. While Ca~(2+) increases first and then decreases slowly due to carbonation reaction. In the range of slurry temperature from 25 ℃ to 70 ℃,Ca~(2+) generation and carbonation are significantly affected by temperature. With the increase of slurry temperature, the leaching mass concentration of Ca~(2+) increases firstly and then decreases, but the leaching mass concentration and leaching amount of other metal elements increase. In the range of solid/liquid mass ratio 1∶3 to 1∶6,the leaching concentration of metal elements decreases and the leaching rate of metal elements increases with the decrease of solid/liquid mass ratio. When sonication time is 20 min, the slurry temperature is 50 ℃,and the mass ratio of solid to liquid is 1∶5,the leaching rate of potassium reaches 47.22%. Sonication time, slurry temperature and solid-liquid mass ratio have certain effects on the leaching process of trace heavy metals. The leaching rate and amount of heavy metals remain at a very low level within the parameters explored in the experiment. In the typical operating parameters: the leaching rates of cobalt(Co),chromium(Cr),nickel(Ni) and lead(Pb) are lower than 0.10%,0.30%,0.05% and 0.10% for 30 min of sonication time, 25 ℃ of slurry temperature, and 1∶5 solid-liquid mass ratio. Considering the implementation and operation cost of the technical system comprehensively, the suitable sonication time is 15-20 minutes, the slurry temperature is 40-50 ℃,and the mass ratio of solid to liquid is 1∶3-1∶5. By comparing the key alkali metal elements, sulfur and chlorine elements in the leaching solution treated by ultrasonic-assisted leaching and the residue, a large number of macro-soluble elements migrate into the filtrate, and the content of trace heavy metals is very low. It is of practical significance for the leaching solution to be used as fertilizer and soil regulator. Due to the leaching of soluble alkali metal salt and chloride, the content in the residue is reduced significantly, which is favorable for its use as the raw material of industrial building materials.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 8491K]

  • Effect of dispersant on the slurry ability of semi-coke water slurry and its adsorption kinetics

    YAO Yaqian;YANG Zhiyuan;MEMG Zhuoyue;LI Yinyan;ZHU Hanbo;College of Chemistry and Chemical Engineering,Xi′an University of Science and Technology;Key Laboratory of Coal Resources Exploration and Comprehensive Utilization of Land and Resources;

    In order to solve the problem of the waste of semi-coke resources in China, the preparation of semi-coke water slurry with semi-coke powder instead of raw coal can not only alleviate the pressure of oil demand, but also provide a new way for the utilization of semi-coke powder. In this paper, the properties, adsorption mechanism and adsorption kinetics of anionic dispersants were studied by using Shenfu semi-coke powder and five different dispersants(methylene dinaphthalene sulfonate NNO, sodium lignosulfonate SLS, sodium humate SH, polycarboxylate PCE, complex anion-anion NNO/PCE). The rheological behavior of semi-coke water slurry prepared with each dispersant was studied. The semi-coke water slurry with different dispersants shows pseudoplastic fluid characteristics. When NNO/PCE dispersant is added, the apparent viscosity of the slurry is only 359.3 mPa·s at the shear rate of 100 s~(-1), and the water separation rate is small without hard precipitation. When NNO is used as dispersant, the fluidity is good, but the stability is poor and the water separation rate is the largest. Through the infrared spectrum test of the semi-coke particle with different dispersants, it is found that the addition of dispersants could change the hydrophilicity and hydrophobicity of the semi-coke particle surface.The adsorption test results show that NNO, SLS, SH, PCE and NNO/PCE reach the adsorption equilibrium at 60,60,120,240 and 240 min, respectively. The increasing trend of adsorption capacity is NNO/PCE(8.796 mg/g)>PCE(7.977 mg/g)>SH(6.845 mg/g)>SLS(3.718 mg/g)>NNO(1.029 mg/g). The pseudo-second-order rate equation can well describe the adsorption kinetics of dispersant on the surface of semi-coke. Finally, the adsorption mechanism model of anionic dispersants was proposed. The results show that the adsorption of anionic dispersants in semi-coke water slurry is mainly due to the enhancement of electrostatic repulsion in semi-coke particles.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 11092K]

  • Performance prediction of circulating fluidized bed unit based on machine learning

    HAN Yi;ZHANG Qiyue;DUAN Lunbo;WANG Yankai;YU Yingli;FU Xuchen;RONG Jun;SUN Shichao;Inner Mongolia Electric Power Research Institute Branch,Inner Monglia Electric Power (Group)Co.,Ltd.;Key Laboratory of Energy Thermal Conversion and Control,Ministry of Education,Southeast University;

    Coal power is an important supporting and regulating power supply in the clean and low-carbon transformation of power system. However, the technical output of thermal power units is hindered due to factors such as low-quality coal combustion, which seriously affects the safe operation of power grid and new energy power consumption. In view of this, a projection model building method based on the integration of mechanism simulation and data drive was presented in this paper. The sample space of boiler thermal system was constructed by mechanism simulation, and the unit output prediction was carried out based on mathematical projection. Considering the theoretical accuracy of mechanism simulation and the strong generalization of mathematical projection, the dynamic boundary output prediction of circulating fluidized bed units and the analysis of output blocking factors were realized under the condition of multi-factor coupling. The test results of 300 MWe demonstration unit shows that: considering the three influencing factors of auxiliary machine limitation, heating surface parameter overrun and key parameter overrun, the alarm values for exceeding the limit of operating parameters such as coal feeder, induced draft fan, slag cooler, bed temperature, screen wall temperature and fluidization wind speed are set respectively. The maximum deviation of mechanism simulation is 3 ℃,and the error rate is less than 2%. The BP neural network model with 7 inputs and 1 outputs is screened and designed based on the principal component analysis method. After network optimization by genetic algorithm, the network training and prediction are carried out by using 32 training samples and 5 test samples. The relative error of model training is within ±1.2%,the relative error of model prediction is within ±1.5%,ind icating that there is high accuracy, generalization ability, and worth reference.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 5943K]

  • Predictive model of coal mill safety evaluation based on PCA-GRNN

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

    The coal mill is an important auxiliary equipment for the operation of the boiler, and its performance safety directly affects the safety of the entire thermal power plant. Since the safety evaluation of coal mills in power plants cannot be fed back in real time, a predictive model for safety evaluation of coal mill was established by combining principal component analysis(PCA) with generalized regression neural network(GRNN).Firstly, the actual operation data of coal mill equipment were regarded as experimental samples, and principal component analysis was used to analyze the principal component for many variables affecting the safety of coal mill. Secondly, the safety evaluation and prediction model of coal mill was constructed based on generalized regression neural network(GRNN), and the crucial components were considered as the input variable, and the corresponding historical expert rating was treated as output variable, and the leave-one-out method was adopted to divide training samples and test samples to improve the training accuracy of network model. Finally, the safety evaluation prediction models were established based on GRNN neural network, PCA-BP neural network and BP neural network. The relative errors and time cost of the four prediction models were compared, respectively.The results show that the variance contribution rate of the three principal components F1, F2 and F3 extracted by PCA reaches 96.55%.Based on PCA-GRNN neural network, the average relative error of the prediction model for coal mill safety assessment is minimal and less time costly.The effectiveness of the predictive model of coal mill′s safety evaluation established by PCA-GRNN neural network is verified.

    2022 06 v.28;No.142 [PaperDigest][OnlineView][HTML全文][Download 11875K]
  • 下载本期数据