• Research progress of thermochemical sulfur-iodine cycle water decomposition for hydrogen production

    WANG Zhihua;ZENG Junjie;HE Yong;LI Mingyang;WANG Xiaoding;State Key Laboratory of Clean Energy Utilization,Zhejiang University;Dongfang Electric Co.,Ltd.;

    With the increasing shortage of fossil energy and serious environmental pollution, it is urgent to seek efficient, clean and renewable energy. Hydrogen energy, as a new password of modern energy industry system, has attracted extensive attention in recent years due to its advantages of cleanliness, renewability, storage and wide range of application. At present, there are many ways to produce hydrogen, but the large-scale, efficient, low-cost and green ways are the basis of the future hydrogen energy economy. Among them, thermochemical sulfur-iodine cycle(iodine-sulfur cycle) is recognized as one of the most promising hydrogen production methods due to its above advantages in water splitting hydrogen production. The basic research on the thermochemical sulfur-iodine cycle water splitting hydrogen production was reviewed from three aspects: Bunsen reaction, H_2SO_4 decomposition and HI decomposition. Secondly, the sulfur-iodine cycle systems that had been established in various countries were summarized, and the latest progress in the nuclear energy-coupled sulfur-iodine cycle hydrogen production process was introduced. Finally, the current nuclear energy coupling sulfur-iodine hydrogen production was discussed and analyzed from the aspects of economy, environmental protection and safety, in order to provide new ideas for future research and development. It is very important to find a new method for efficient separation of reactants in the Bunsen reaction part. The main research for the decomposition of H_2SO_4 and HI at this stage is still focused on the development of stable, efficient and low-cost catalysts. Thermochemical sulfur-iodine cycle water splitting hydrogen production technology has made great progress after decades of research. The harsh high temperature and high corrosion environment and complex coupling process are the main reasons that limit its scale and industrialization in actual hydrogen production. Developing corrosion-resistant and heat-resistant systems made of industrial structural materials, and continuing to optimize and simulate coupled processes are the future development directions of thermochemical sulfur-iodide cycle water splitting hydrogen production technology.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 29092K]

  • Characteristics and mechanism of methane redox NO_x by catalysts with different carrier particle sizes

    CHEN Chen;AN Donghai;SONG Jialin;CHENG Xingxing;School of Energy and Power Engineering,Shandong University;Changji University;

    Al_2O_3 supported catalysts of different particle sizes(10,20,30 nm) and Cu/SMA_((a))(a=10,20,30) supported by nano-scale alumina were prepared by means of loading, and their catalytic efficiency was tested. The results show that the order of methane catalytic reduction of NO and methane catalytic oxidation efficiency is Cu/SMA_((20)) > Cu/SMA_((10)) > Cu/SMA_((30)) > Cu/Al_2O_3. Cu/SMA_((20)) methane has the best catalytic capacity to reduce NO. The physical and chemical properties of the catalyst were further analyzed by TEM, BET, XPS and NH_3-TPD. The TEM test results show that small particles of nano-sized alumina as catalyst carrier could disperse copper oxide as active component better, which is conducive to enhancing the catalytic activity of the catalyst. The results of XPS and NH_3-TPD show that Cu/SMA_((a))(a=10,20,30) catalyst has more oxygen vacancies and acidic sites than Cu/Al_2O_3 catalyst. Moreover, the catalyst contains a well-developed pore structure, which provides more contact sites for the REDOX reaction of methane under the action of the catalyst, and the catalyst contains a higher vacancy oxygen O_β, which increases the denitrification efficiency of the catalyst. The reaction mechanism was further analyzed by H_2-TPR and TR-FI. The Cu~(2+) species in the catalyst are more likely to be reduced to Cu~+ in the reaction, and Cu~+ plays a synergistic role in the subsequent denitration reaction and promotes the catalytic reduction of NO in methane. NO first reacts with O_2 to form an intermediate substance. CH_4 then undergoes a REDOX reaction to form N_2.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 30810K]

  • Research progress of carbon dioxide adsorption by carbon-based materials

    YU Hang;MENG Hong;YANG Xiangfu;JIN Junsu;College of Chemical Engineering,Beijing University of Chemical Technology;State Key Laboratory of Chemistry and Utilization of Carbon-based Energy Resources,College of Chemistry,Xinjiang University;

    In recent years, the concentration of greenhouse gases, mainly CO_2, in the atmosphere continues to increase, which leads to the increasing greenhouse effect. Carbon dioxide capture, utilization and storage(CCUS) is the bottom technology to achieve carbon neutrality, and the cost of carbon dioxide capture accounts for about 70% of the whole CCUS chain. The development of low-cost carbon dioxide capture technology is the top priority to promote the application and promotion of CCUS technology. While researchers have developed a variety of advanced materials(such as zeolites, metal-organic frameworks, mesoporous silica, and polymers) to cope with CO_2 capture, research on activated carbon(ACs) is still mainstream. Carbon material has the advantages of wide source, low price, abundant pore structure, stable physical and chemical properties, etc. It is a kind of carbon dioxide adsorption material with great application potential. The existing carbon-based adsorption materials still have the disadvantages of low carbon dioxide adsorption capacity and poor adsorption selectivity, which restricts their application in the field of carbon dioxide capture. Researchers at home and abroad have carried out a lot of modification work of carbon-based adsorption materials to meet the needs of industrial applications. The research progress at home and abroad in recent years was introduced by combing the two aspects of carbon-based adsorption material pore-making and surface modification. The existing pore-making methods such as physical activation method, chemical activation method, template method and surface oxidation, nitrogen hybrid, sulfur hybrid and metal hybrid modification methods were summarized, and the advantages and disadvantages of different methods were comprehensively analyzed. In view of the current pore-making technology, the soft formwork agent with lower cost and the hard formwork agent with easier processing are considered. Among many modification methods, nitrogen hybrid modification and metal hybrid modification are studied more, and they are also one of the most likely ways to achieve large-scale production of carbon-based adsorption materials.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 12511K]

  • Recent progress on coal-based carbon membrane in wastewater treatment

    HAN Qian;LIU Zhiming;YANG Xiaoqin;LIN Zhe;QIN Zhihong;KONG Weiwei;School of Chemical Engineering and Technology,China University of Mining and Technology;Jiangsu Alwater Environmental Technology Co.,Ltd.;

    Coal is high-quality raw material for carbon membrane due to its high carbon content, abundant reserves, and affordable availability. Coal-based carbon membrane using coal as raw material for wastewater treatment has advantages of high separation efficiency for a variety of wastewater, simple process operation, good repeatability, and can be used for large-scale industrial treatment. Although coal-based carbon membrane can remove pollutants with sizes of about 0.05-10.00 μm in the wastewater by screening and adsorption, the removal of organic pollutants and heavy metal ions with particle size much smaller than the membrane pore is limited. Moreover, the single coal-based carbon membrane separation will face the problems such as reduced separation capacity and fouling resistance ability due to the adsorption and accumulation of pollutants on the external and internal surfaces of the membrane after long-term operation. Therefore, by choosing specific coal-based carbon precursor, appropriate support and additives as raw materials, as well as optimizing the preparation process conditions, the goal of improving the pore size and distribution of carbon membranes and enhancing the hydrophilicity is achieved. At the same time, by utilizing the electrical conductivity of coal-based carbon membrane, and the methods of coupling with electrochemical or advanced oxidation processes are adopt on the basis of traditional carbon membrane separation process to improve the ability of treating various wastewater and solve the membrane pollution problem, such as electrochemical oxidation, electroadsorption, electroflotation and electrofenton oxidation. These coupling technologies can improve membrane separation efficiency, enhance membrane fouling resistance and reduce energy consumption, which are new developments of coal-based carbon membrane application in wastewater treatment and are of great significance for efficient and clean utilization of coal and industrial wastewater treatment. The preparation of coal-based carbon membrane in recent ten years and the principle, characteristics and research progress of electrochemical or advanced oxidation processes coupled membrane separation technology applied to wastewater treatment were reviewed from the above aspects, and the future research direction of coal based carbon membranes for wastewater treatment was prospected.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 5020K]

  • Characterization of soluble polycyclic aromatic hydrocarbons in lignite and its low-temperature pyrolysis semi-coke

    LU Mengqian;LI Shan;SHI Yungu;ZHANG Hui;LIANG Handong;State Key Laboratory of Coal Resoures and Safe Mining,China University of Mining and Technology(Beijing);College of Geoscience and Surveying Engineering,China University of Mining and Technology(Beijing);School of Mechanics and Architectural Engineering,China University of Mining and Technology(Beijing);

    Low-temperature pyrolysis is one of the important ways to achieve clean and efficient utilization of lignite. Semi-coke as the solid product of pyrolysis is widely used in both industrial and civil clean fuels. In this study, three lignites from Inner Mongolia(SHM), Indonesia(YN) and Mongolia(WM), and their pyrolyzed semi-coke at 550℃ were used as samples to investigate the concentration and composition changes of soluble polycyclic aromatic hydrocarbons(PAHs) by extraction combined with GC/MS analysis. The results showed that the concentrations of total PAHs(∑PAHs), 16 US EPA priority PAHs(∑16PAHs) and their alkylated derivatives(∑aPAHs) of the three lignites were in the ranges of 4 362-125 635, 1 871-35 039 and 1 723-61 757 ng/g, respectively. It revealed that the concentration of PAHs in lignite from different sources was significantly different, and aPAHs were abundant in all lignite. The concentrations of ∑PAHs, ∑16PAHs and ∑aPAHs the three semi-cokes were in the ranges of 4 679-10 289, 1 831-6 354 and 744-2 737 ng/g, respectively. The relative abundance of PAHs in the semi-cokes with respect to the corresponding lignites was different. SHM semi-coke had a lower concentration of PAHs than SHM lignite, YN semi-coke had a higher concentration than YN lignite, and the PAHs content of WM semi-coke were similar to that of raw coal, but the parent 16PAHs content of WM semi-coke were relatively higher than that of WM raw coal. The ∑aPAHs concentrations of three semi-cokes were all lower than the corresponding parent ∑16PAHs concentration, indicating that the PAHs retained in semi-coke were dominated by the more thermodynamically stable parent form. The composition of PAHs in both lignite and semi-coke was dominated by 2-3 rings low molecular weight PAHs. Especially the concentration of naphthalene and alkylated naphthalenes in YN semi-coke was the main reason for the increase of the total concentration of PAHs. It indicated that cleavage reaction occurred within the coal molecule during pyrolysis and a large number of small molecules PAHs were generated. The different changes of soluble PAHs in different lignites and their semi-cokes not only reveal the different physical and chemical reactions of different coals during pyrolysis from the molecular level, but also reflect the differences in the macromolecular structural characteristics of coal.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 13532K]

  • Expansion law of temperature field during bulk coal pyrolysis

    SU Qianqian;LI Wenjun;CHEN Yanpeng;LI Tianyu;School of Chemical and Environmental Engineering,China University of Mining and Technology(Beijing);School of Chemical and Environmental Engineering,North China Institute of Science and Technology;Research Institute of Petroleum Exploration and Development;

    Drying and pyrolysis are related to the composition of underground coal gasification product gas and the efficiency of gasification working surface. In order to investigate the expansion law of pyrolysis temperature field in dry distillation zone during underground coal gasification process, the 300 mm raw coal block of Heshun lean coal and the artificially prepared Mengdong lignite block were selected as the research objects. The large size fixed-bed pyrolysis reaction device was used to conduct a single-sided constant temperature heating experiment on bulk coal under N_2 atmosphere. The temperature of each measuring point during the experiment was collected by a total of 50 thermocouples evenly arranged in four layers of bulk coal, and the temperature field distribution map of bulk coal pyrolysis was drawn. The results show that the pyrolysis temperature field of bulk raw coal expands upward in a multi-parabolic shape with multi-fissures as the center, while the pyrolysis temperature field of artificial bulk coal moves upwards in an approximate horizontal shape. The movement rate of drying line and characteristic temperature line of bulk coal pyrolysis gradually decreases with the increase of the pyrolysis time, and the movement rate of drying line is greater than that of characteristic line. The heat transfer rate and the movement rate of drying line and characteristic temperature line of the bulk raw coal is higher than that of the artificial bulk coal. The movement rate of drying line and characteristic temperature line of bulk raw coal during pyrolysis for 6 h are 21.0 and 12.3 mm/h, respectively. Due to the existence and development of fissures in the bulk raw coal, the cracks undergo convective heat transfer during pyrolysis, which improves the heat transfer rate of raw coal. At the same time, the fissure development and heat transfer promote each other, so that the pyrolysis temperature field of raw coal expands in a multi-parabolic shape with multiple fissures as the center. The movement rate of drying line and characteristic temperature line is improved by the fissure of raw coal, especially there is the significanteffect on drying line. Therefore, the development of fissures and the large amount of flue gas generated by combustion in the oxidation zone will strengthen the convective heat transfer in the coal seam and increase the expansion rate of the pyrolysis temperature field of underground coal gasification in the actual process of underground coal gasification.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 21504K]

  • Research progress on regulation and analytical methods of metal ion location in Y-type zeolite

    ZHAO Jinchuan;WEN Zhihui;WANG Jingjing;CHANG Liping;BAO Weiren;MA Jinghong;LIAO Junjie;State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology;Key Laboratory of Coal Science and Technology of Ministry of Education,Taiyuan University of Technology;Shanxi Zhejiang University New Materials and Chemical Research Institute;College of Chemistry and Chemical Engineering,Taiyuan University of Technology;

    Y-type zeolite is widely used in the field of desulfurization. Studies have shown that the removal capacity of sulfide in pollutants can be effectively improved by the metal-modified Y-type zeolite adsorbents obtained by metal ion exchange. However, due to the fact that the Y-type zeolite has three different size structures: supercage, sodalite cage and hexagonal prism cage, larger sulfides can only be adsorbed and removed by entering the supercage according to the size selectivity. Therefore, it is very important to improve its adsorption performance by analyzing and controling the location of metal ions in Y-type zeolite. In this paper, the location control methods and analytical methods of metal ions in Y-type zeolite were summarized. The effects of the size of metal complexes, the calcination temperature and atmosphere during the preparation of zeolite, and the introduction methods of metal species on the position of metal ions in Y-type zeolite were summarized. The progress of characterization methods such as X-ray diffraction analysis(XRD), Rietveld structure refinement, in situ infrared spectroscopy(FTIR and Py-FTIR), and electron paramagnetic resonance(EPR) in analyzing the micro positioning of metals in Y-type zeolite cages was reviewed. The effective methods for characterizing the various metal species loaded on Y-type zeolite were analyzed. The size of metal complexes can be adjusted by complexing metal ions with organic complexes so that they can enter more into the supercages during the ion exchange process, achieving the purpose of regulating the location of metals in different cages of Y-type zeolite. The dehydration of hydrated metal ions caused by high temperature calcination is transfered from Y-type zeolite supercages to sodalite cages. The location of metal ions can be controled by changing the calcination temperature. The calcination atmosphere will affect the valence state of the metal ions. The metal oxides obtained by calcination in the air atmosphere are prone to deposit and block the pores, hindering the migration of the metal ions. Some metal ions can be also reduced due to the calcination under nitrogen atmosphere and change the active components on the zeolite. The appropriate calcination temperature and atmosphere can affect the placement of metal ions in the Y-type zeolite cage. The introduction method of metal species will affect its distribution inside and outside the Y-type zeolite cage, and regulate its location in each cage of the Y-type zeolite. Y-type zeolite sieves have broad application prospects in the field of adsorption separation and catalysis, in which metal modification is a commonly used means to enhance the performance of Y-type zeolite sieves. In order to enhance the utilization rate of metal ions and increase the metal active sites, it is necessary to combine with suitable and analytical methods to clarify the migration law of metal ions in Y-type zeolite sieves under different preparation conditions. Further attention is focused on how to inhibit the migration of metal ions in the Y-type zeolite supercage under high temperature calcination, ensuring that more metal species are localized in the supercage. The mechanism by which the mode of introduction of metal species affects their colonization is unclear, and further research is needed. The methods for resolving the fall of metal ions in different cages of Y-type zeolite sieves are not intuitive, and some methods are controversial and need to be further explored and investigated.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 12756K]

  • Migration and transformation characteristics of mercury during mixing of municipal sludge with coal gangue

    DUAN Wangzhi;ZHANG Kaihua;ZHANG Kai;Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation,North China Electric Power University;

    There is a certain degree of complementarity between municipal sludge and coal gangue in combustion properties, and both contain a large amount of heavy metal mercury pollutants. Therefore, it is necessary to study the migration and transformation characteristics of mercury in the mixed combustion process. The occurrence forms of mercury in sludge and coal gangue samples, as well as the release characteristics of mercury during combustion were studied by chemical step extraction method, and the effects of temperature, mixing ratio and atmosphere on the migration behavior of mercury in the samples were investigated. The results show that No.1 sludge is mainly composed of sulfate, carbonate and oxide-combined mercury and residual mercury. The content of residual mercury in No.2 sludge is the highest. The main content of coal gangue is sulfide-bound mercury. The mercury released in the low temperature zone of sludge from 200 ℃ to 390 ℃ is mainly organic and carbonate bonded mercury, while the mercury released in the high temperature zone from 390 ℃ to 450 ℃ is mainly sulfide bonded mercury. The mercury released by gangue at low temperature ranging from 300 ℃ to 400 ℃ is mainly organic binding, carbonate binding and oxide binding states, while the mercury released at high temperature ranging from 400 ℃ to 600 ℃ is mainly sulfide binding and some oxide binding states. The release of mercury in coal gangue at low temperature in advance is promoted due to sludge mixing, and the promotion effect becomes stronger with the increase of sludge mixing rate. With the increase of oxygen content in the atmosphere, CO_2 produced in the combustion process will be adsorbed on the surface of the particles and the heat transfer resistance is increased, thus inhibiting the release of organic-bound mercury and some carbonate-bound mercury in the mixture. Meanwhile, it is found that the effect of atmosphere on the release behavior of mercury in the high proportion of sludge mixture is weakened.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 26573K]

  • Calculation of heating surface wall temperature and operation measures for 660 MW ultra supercritical CFB boiler under electricity failure

    ZHOU Xu;ZHOU Yanjun;LI Weicheng;LU Jiayi;LIU Xinglei;DENG Qigang;LI Yinlong;YANG Dong;School of Energy and Power Engineering,Xi'an Jiaotong University;Key Laboratory for Clean Combustion and Flue Gas Purification of Sichuan Province;

    It is important to ensure the heating surfacesafety of ultra-supercriticalcirculating fluidized bed(CFB)boiler under electricity failure. The factors that affect the safety of heating surfaces of a supercritical circulating fluidized bed boiler after a power outage accidentwere analyzed. The transient flow heat transfer calculation model for the boiler heating surfaces was established based on the conservation of mass, momentum, energy, and the heat storage equation of the tube-wall. A program for calculating the dynamic characteristics of the boiler steam water systemwas also developed, which can calculate the variation of the working fluid temperature and tube-wall temperature with timeon the heating surface of a boiler under power loss conditions.The result shows that the high-pressure bypass valve needs to exhaust steam at a flow rate of 40% BMCR, with a minimum critical time of 110s for exhaustwhen the safety of the boilerheating surface is ensured. Meanwhile, the inlet of the economizer needs to be replenished with water at a flow rate of 140 t/h. Theworking fluid and tube-wall temperature of the water wall, low-temperature superheater, medium temperature superheater, and high-temperature superheater rise first and then decrease over timeunder this condition. The highest value of tube-wall temperature is lower than the allowable temperature for heating surface material. The measures proposed can ensure the safety of heating surfaces of the ultra-supercritical CFB boiler under electricity failure, solve the problem of overheating of the heating surface after the power loss accident of the CFB boiler, which provides guidance for the operation of the power plant.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 13237K]

  • Performance analysis of waste heat deep utilization of cement plant based on carbon dioxide capture

    XU Decao;LI Xiantao;LI Nan;WANG Yihan;CHEN Heng;PAN Peiyuan;State Grid Qinghai Electric Power Company;Green Energy Development Research Institute(Qinghai);School of Energy,Power and Mechanical Engineering,North China Electric Power University;

    The dual carbon goal is a solemn commitment made by China to the world in the era of global carbon emission reduction, and it is also an inherent requirement for achieving sustainable development. As the third largest source of greenhouse gas emissions after power generation and steel industry, the cement industry should undertake the task of carbon reduction in the future. At present, the waste heat utilization of cement kiln only stays in the power generation stage and does not meet the requirements of the times for further development and utilization. Therefore, a new integrated carbon capture cement kiln waste heat utilization multigeneration system was proposed. Revenues from sales of electricity, heat and cooling are used to offset the investment costs of expensive carbon capture. The use of waste heat from cement production is not sufficient to cover all carbon capture costs, but it can meet some CO_2 capture costs, so that an appropriate carbon capture rate(18.89%) can be determined. The proposed new system can be divided into two modes. In the heating mode, 5.52 MW of energy can be recovered from the carbon capture process, and the overall exergic efficiency reaches 10.28% and 10.71%. In the cooling mode, 3.66 MW of energy is recovered to drive the absorption refrigeration system to provide 0.82 MW of cooling capacity. Economic analysis shows that the annual revenue of the system reaches 20.491 3 million yuan, while the carbon capture cost(η_(COA)) is as low as 281.54 yuan/t(in CO_2). This will provide a feasible reference for cement production to meet the carbon reduction requirements in the future, further utilize the waste heat of cement plants and reduce the investment in carbon capture.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 31507K]

  • Ash and slag characteristics under co-gasification of coal and extract residue of direct coal liquefaction residue

    LIU Zhen;LI Jun;ZHANG Jiansheng;Department of Energy and Power Engineering, Tsinghua University;CHN Energy National Institute of Clean and-Low-Carbon Energy;

    Co-gasification with coal is an effective way to achieve the resource utilization of coal direct liquefaction residue(ER) and improve the overall economy of direct coal liquefaction project. The flow properties of slag in the gasification process is the key parameter that affects the gasification operating conditions. The fusion characteristics, viscosity-temperature characteristics and crystal characteristics co-gasification with coal and ER were analyzed by ash fusion point meter, high-temperature rotating viscometer, XRD(Diffraction of X-Rays) and SEM(Scanning Electron Microscope). Based on the coal ratio and operating conditions of Shell gasifier, the optimal blending ratio of ER and gasification operating conditions were determined from the perspective of ash chemistry. The results show that there is high ash, high iron, high calcium and high sulfur in the ER,and its ash composition is slightly alkaline. With the increase of the amount of ER in coal, the ash content, iron content and w(SiO_2)/w(Al_2O_3) increase gradually. The whole liquid phase temperature(T_(liq)) becomes lower when the mass fraction of the raffinate is above 8%, and the type of slag changes from glass to crystalline when the amount of raffinate added is over 20%. The XRD and SEM analysis results indicate that the precipitation of anorthite cause a change in the type of slag. The precipitation of calcium feldspar is mainly due to the addition of residual substances, which reduces the viscosity of slag and enhances the diffusion ability of clusters in slag. Considering to the conditions of Shell gasifier for operation and the requirements for iron content in coal ash, the optimal blending ratio of ER is 10% for co-gasification of coal and ER, and the corresponding operating window is 1 335-1 557 ℃. The research results provide guidance for co-gasification of coal and ER, and can improve the economy of the direct coal liquefaction process.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 25916K]

  • Research progress and application prospect of high-value utilization of coal gasification slag

    FENG Xianggang;WANG Haiyan;GE Fenfei;ZHANG Yinmin;ZHANG Yongfeng;Chemical Engineering College,Inner Mongolia University of Techmology;Inner Mongolia Key Laboratory of Efficient Recycle Utilization For Coal Based Waste;China Inner Mongolia Autonomous Region Solid Waste and Soil Ecological Environment Technology Center;

    China′s energy resource endowment and the development of coal gasification industry have made the emission of coal gasification slag up to 60 million t/a. A large amount of coal gasification slag is not in line with the concept of clean, low-carbon and efficient use of energy. In the process of coal gasification slag absorption treatment, due to the high water content and carbon content, the way of large-scale utilization is limited, so it is a trend to change the traditional idea and develop the performance in the direction of high value. Research progress of high-value gasification slag was focused on, the sources and physical and chemical properties of coal gasification slag and the research status at home and abroad in the high-value gasification of catalyst framework was summarized, polymer reinforcement, porous materials, agricultural compost and other aspects. The limitations of high-value utilization was put forward, and the future development direction was looked forward. High-value utilization of coal gasification slag is the main form of solid waste performance development, which can reduce production costs and environmental pollution. Moreover, the characteristics of coal gasification slag show that coal gasification slag is a misplaced resource, and moderate development of its application in high-value utilization can realize the transformation of waste into treasure.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 11715K]

  • Preparation of active calcium oxide by calcining calcium carbide slag and the effect of particle size

    YAN Kun;ZHU Ganyu;LI Huiquan;ZHENG Yuewu;ZHANG Jianbo;YANG Yue;XING Gang;ZHOU Shaoxiang;CHANG Yongsheng;MENG Ziheng;National Engineering Research Center of Green Recycling for Strategic Metal Resources,CAS Key Laboratory of Green Process and Engineering,Institute of Process Engineering,Chinese Academy of Sciences;School of Chemical Engineering,University of Chinese Academy of Sciences;Huaneng Qinbei Power Generation Co.,Ltd.;Beijing Genyuan Environmental Protection Co.,Ltd.;

    The recycling of calcium carbide slag-calcium oxide-calcium carbide is an effective way to realize the recycling of calcium carbide slag. However, due to the complex composition of calcium carbide slag and the difficulty of purification, large-scale preparation of active calcium oxide for recycling has not been achieved at present. In this paper, the changes in phase morphology during the calcination process of calcium carbide slag were systematically investigated, and the composition differences of calcium carbide slag with different particle sizes were studied. By studying the particle size characteristics of calcium carbide slag and the roasting characteristics of calcium carbide slag of each particle size, the influence of particle size classification on the preparation performance of active calcium oxide from calcium carbide slag was clarified. The results show that the impurities in carbide slag are concentrated in the particles less than 45 μm and larger than 180 μm, and the acid insoluble matter, Fe and C, etc. are mainly concentrated in the particles more than 150 μm. The calcium component is gradually transformed into calcium oxide in two stages ranging from 350 to 460 ℃ and 550 to 720 ℃ during the roasting process. Most of the carbonaceous impurity particles can decompose below 800 ℃, which affects the performance of preparing activated calcium oxide products. The compressive strength of activated calcium oxide is mainly affected by particle size, and the metallurgical activity is jointly affected by particle size and composition. The fine particles will fill the intergranular gap during the pressing process, increasing the strength but hindering water penetration. Excessive impurities in coarse particles are difficult to decompose and form large pores, affecting the strength and activity of products. 45-106 μm is more suitable for the preparation of active calcium oxide, with an activity of 411 mL(4 mol/L standard hydrochloric acid) and the compressive strength of 2.46 MPa. The above research can provide a good reference and basis for carbide slag recycling.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 26005K]

  • Review on geopolymer preparation by alkali activation of coal fly ash

    SUN Hao;MA Zhibin;LU Guangjun;LIU Jinyan;LIAO Hongqiang;Institute of Resources and Environmental Engineering,Shanxi University;State Environmental Protection Key Laboratory on Efficient Resource-utilization Techniques of Coal Waste,Shanxi University;School of Electricity and Architecture,Shanxi University;

    Due to the large amount of CO_2 emitted from the production process of traditional portland cement-based building materials, the new low-carbon cementing materials represented by geopolymer have become a research hotspot in recent years. Fly ash, as a bulk industrial solid waste in China, is rich in aluminosilicates, and the preparation of geopolymer by alkali-activated method can realize the bulk consumption of fly ash. In this paper, the evaluation method of alkali-activated reactivity of fly ash was discussed, the reaction mechanism of fly ash and alkali activator was summarized, the effects of key factors such as fly ash type, activator, raw material ratio and curing system on the properties of geopolymers were summarized, and the existing problems in current research were proposed, and the future research directions from the perspective of evaluation of active components of fly ash and elemental composition of alkali activation system were prospected. The reactivity evaluation methods of fly ash mainly include Rietveld full spectrum fitting method, saturated lime solution absorption method and acid-base dissolution method. The reaction process of alkali-activated fly ash can be divided into four stages: dissolution, gelation, condensation and polymerization. The dissolved Si/Al molar ration from fly ash in the process of decomposition has an important influence on the gel structure and mechanical properties of geopolymer, and the optimal Si/Al molar ration obtained by different studies has a great difference. The effects of raw material ratio, curing system, gel structure and other factors on the properties of geopolymer obtained by different studies has a great difference, which brings difficulties to the research on the mechanism of fly ash alkali excitation reaction and the synthesis of geopolymer. In the future, a unified calculation method for the proportion of elements in alkali-activated fly ash should be established according to the physical and chemical properties of different types of fly ash, laying a theoretical foundation for the unified design standard of fly ash-based geopolymer synthesis.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 25907K]

  • Coal mine filling material based on cement with high solid waste content

    ZUO Ranfang;FENG Bo;DONG Yang;ZHANG Dong;National Institute of Clean-and-Low-Carbon Energy,CHN Energy;

    In the process of coal mining, a large amount of coal resources are wasted by reserving coal pillars to prevent the collapse of gob. In order to ensure the sustainable development of coal resources, it is urgent to solve the problem of "three pressure coal", so it is imperative to study the filling mining technology. Using coal gangue as aggregate, fly ash and a small amount of cement as cementing material, combining with the different characteristics of fly ash in different power plants, fly ash compounding technology was adopted to solve the problems of poor slurry fluidity and low strength, and a mine filling material was prepared with high solid waste content, low cost, high flow and high strength. The effects of composition, morphology and particle size of fly ash on the strength and fluidity of filling materials in 3 power plants were analyzed. The results show that the spherical shape of pulverized coal furnace fly ash FA1 can significantly improve the fluidity of backfill material, while the irregular shape of circulating fluidized bed fly ash FA2 and FA3 has no significant effect on improving the fluidity of backfill material, but it has a significant effect on improving the strength of backfill due to the large amount of active calcium oxide. The higher the content of active calcium oxide in fly ash, the higher the strength of backfill, but the worse the fluidity. Therefore, by combining pulverized coal furnace ash FA1 with circulating fluidized bed ash FA3, the fluidity is improved and the compressive strength is maintained. The results show that when 20% FA1 and 80% FA3 are combined and 94% of the cement is replaced by fly ash, the prepared slurry has good fluidity, and the 28 d strength is up to 4.5 MPa, which meets the C4 grade in the line standard JC/T 2468—2018 "Cement-based Backfill Materials", that is, the 28-day strength is ≥4 MPa. The research shows that the ratio of clean pulp to gangue is 1∶4, and the gangue of the mine filling material prepared has good encapsulation property, and the strength of 28 d is 4.2 MPa, which is slightly lower than that of the clean pulp. When the ratio of clean pulp to gangue is 1∶6, the packing property of gangue prepared is poor, and the strength of 28 d is only 1.3 MPa. Therefore, the optimal ratio of clean pulp to gangue is 1∶4, that is, the maximum amount of gangue accounts for 80% of the filling material, cement accounts for 1.2%, and fly ash accounts for 18.8%.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 25339K]

  • Contrastive research on comprehensive emission of haul truck based on coal-hydrogen synergy and diesel engine

    LIU Shaoquan;WANG Haijun;SHI Yixiang;China Instiute of Coal Science,China Coal Technology & Engineering Group;Department of Energy and Power Engineering,Tsinghua University;

    Haul truck transportation is a key production system in opencast coal mine. With the increasing requirements for green, low-carbon, clean and environmental protection, energy conversion and haul truck power, as one of the main sources of atmospheric pollutants and greenhouse gas emissions from opencast coal mine, have become research hotspots. In order to research the comprehensive emission of energy and power scheme of haul truck, a certain open-pit coal mine and its transportation system were taken as the research object.Three technical schemes based on coal-hydrogen synergy and another comparison plan of traditional technology routes were designed for the two subsystems of energy conversion and haul truck power.The research scope and boundary conditions were determined, and the research models and data lists were established.Quantitative analysis and comparative study were conducted on the atmospheric pollutants and greenhouse gas emissions during the fuel cycle of transporting 1 m~3·km of earthwork or coal over a period of 10 a. The result shows that Scheme 2 uses green hydrogen power to achieve the best comprehensive emission performance. Schemes 1 and 3 can transfer emissions from haul truck power to energy conversion, which is conducive to adopting centralized and effective measures for emission reduction. The emission reduction focus of Scheme 1 is on desulfurization and dust removal, while the emission reduction focus of Scheme 3 and Scheme 4 is on CO_2 capture, storage, and utilization. Scheme 4 has a large emission of atmospheric pollutants including CO and HC+NO_x from the diesel power system of the haul truck, making emission reduction technology difficult. It is necessary to research on a new clean and efficient power system of the haul truck.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 5241K]

  • Helium extraction process by cryogenic liquefaction of enriched coalbed methane

    XU Jizong;LI Xuefei;YUAN Chongliang;WANG Yongzhong;ZHANG Junliang;GUO Haoqian;LI Xiaoliang;Yaojie Coal and Electricity Group Co.;China Coal Research Institute Co.,Ltd.;Beijing Key Laboratory of Coal Based Carbon Materials;National Energy Technology & Equipment Laboratory of Coal Utilization and Emission Control;

    Helium is one of the important national strategic gases, and the extraction of helium from natural gas is its main industrial source. China is severely constrained by helium monopoly countries due to the lack of natural gas. It is extremely urgent to find the new resources for helium extraction. Helium extraction from concentrated coalbed methane, which is similar to natural gas and does not require complex pretreatment, could be an important direction for China to break the helium "stuck neck". The extraction of helium from concentrated coalbed methane with the co-production of LNG was simulated by Aspen HYSYS, and the influence of intake air temperature, intake air pressure, reflux ration, theory plate number, feed position and composition of feed gas on the energy consumption of helium extraction by cryogenic liquefaction, crude helium and LNG quality was analyzed. The results show that the main energy consuming equipments of helium extraction from concentrated coalbed methane by cryogenic liquefaction are compressor and expander from cycle refrigeration, condenser and reboiler from helium extraction, respectively. The separation effect of helium extraction by cryogenic liquefaction is better under the conditions of low temperature and high pressure of inlet gas. The investment cost of helium extraction by the cryogenic liquefaction is the lowest and the economy is good, when the number of theoretical plates of the primary and secondary helium extraction tower and denitrification tower are 8, 7 and 4, respectively. The concentration of crude helium is increased from 66.68% to 70.49%, the recovery rate of helium is increased from 99.67% to 99.93%, and the output of crude helium is increased from 7.47 m~3/h to 13.28 m~3/h by two-stage low-temperature condensation, with the CH_4 concentration of the feed gas is increased from 86% to 93%, the He concentration is increased from 0.8% to 1.5%, and the N_2 concentration is reduced from 13.2% to 5.5%. For the production scale of 15 000 m~3/d, the total investment of the cryogenic liquefaction helium extraction system of concentrated coalbed methane is about 19.46 million RMB, of which the nitrogen cycle refrigeration compressor accounts for the largest proportion, about 65.58%. The crude helium and coproduct liquefied natural gas(LNG) can be produced from concentrated coalbed methane by cryogenic liquefaction which will be helpful for industrial application of helium extraction from coalbed methane.

    2023 11 v.29;No.159 [Abstract][OnlineView][HTML全文][Download 23039K]
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