2024年07期目次

  • Advances in key technologies of synergistic pollution and carbon reduction by industrial solid waste CO2 mineralization

    LI Lei;PAN Xin;LIU Luyu;State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences;University of Chinese Academy of Sciences;

    In view of the problem of CO_2 and solid waste emissions in industrial processes, it is urgent to reduce pollution and carbon. CO_2 mineralization technology has attracted more and more attention because it can be used as resources while storing CO_2. The utilization of different industrial solid waste as raw materials for CO_2 mineralization was discussed, the advantages and disadvantages of different mineralization processes and the mechanism of CO_2 mineralization were compared and analyzed, and research status and industrial application of different CO_2 mineralization processes were summarized. It is found that at present, there is no mechanical explanation for solid waste CO_2 mineralization, and it is impossible to effectively control the leaching process of metal ions and the efficiency of gas-liquid-solid mass transfer in the mineralization process. At the same time, carbonate products formed by mineralization have some problems, such as large particle size, easy agglomeration and single function. The mechanism of controlling leaching rate and degree, such as surface solvent diffusion, should be further investigated in future research. The dynamic mechanism of nucleation and crystallization of carbonate and the control methods of morphology and particle size of carbonate crystals should be studied. It is important to establish the gas-liquid-solid transport model of coal-based solid waste leaching and mineralized solute, optimize the process parameters, carry out process strengthening, and determine the scale-up law. The whole life cycle and economic evaluation of CO_2 mineralization utilization technology should be further strengthened to make it more energy saving and cost saving. Finally, it is necessary to increase the integration of pilot and demonstration technologies and complete process construction of CO_2 mineralization utilization technology to lay technical support for the industrial development of large-scale pollution reduction and carbon reduction technologies.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 659K]

  • Review on characteristics and resource utilization of coal gasification coarse slag

    ZHANG Kewei;LIAO Changjian;WANG Jing;JIN Ping;WANG Kun;XU Wanyi;Chemical Institute of China Petrochemical Corporation;Dalian Research Institute of Petroleum and Petrochemicals;

    Coal gasification is the core technology to achieve clean and efficient utilization of coal. In China, the output of coal gasification slag is large while the utilization rate is low. Coal gasification slag is usually disposed by storage and landfill, resulting in serious waste of land resources and environmental pollution. The resource utilization of coal gasification slag has become the research emphasis of coal chemical industry, especially the coal gasification coarse slag, which accounts for 70%-80% of the total coal gasification slag. In this paper, three coal gasification processes and the formation of coal gasification coarse slag were introduced, and the physicochemical characteristics and environmental risks of coal gasification coarse slag were summarized, and the research progress of coal gasification coarse slag in the utilization of building materials, soil improvement and high value utilization were sum up. Affected by the main control factors such as coal type and coal gasification process, the physical and chemical characteristics and environmental risks of the gasification coarse slag from different sources are not the same, but they do have some commonalities. The particle size of coarse slag is much higher than that of fine slag, about 50% of coarse slag has a particle size of more than 0.5 mm, and the content of coarse slag of different particle sizes less than 0.5 mm decreases with the decrease of particle size, and the coarse slag also has a smaller specific surface area and a larger average pore size. The carbon residue content of coarse slag is lower than that of fine slag, and the carbon residue content of coarse slag is generally in the range of 3%-20%, which is unevenly distributed in different particle size grade. Generally, the medium particle size coarse slag of about 0.25 mm has a higher carbon residue content. The inorganic components in the slag are mainly SiO_2, Al_2O_3, CaO and Fe_2O_3, of which the acid oxides account for 45%-75%, while the basic oxides account for about 20%-45%. There is a certain enrichment of heavy metals in the coarse slag, including some lithophilic elements such as Ba, Co, Cs, Th, and some non-volatile or semi-volatile elements such as Cr and Ni. In addition, the acid extractable content of heavy metals such As Ni, Cd, As, Cu and Zn in coarse slag is high, which has great environmental risks and needs special attention. The physical and chemical characteristics of coarse slag and its environmental risks have a great impact on the applicable resource utilization. Coarse slag can be widely used in building materials such as mine backfill, road construction, cement and concrete, ceramide and wall materials due to its low carbon residue content and high inorganic component content such as silicon and aluminum. Coarse slag with higher carbon residue content has more loose and porous structure characteristics, which can be used for soil improvement. The special structure of coarse slag and its abundant silicon and aluminum components make the coarse slag have great potential in preparing porous adsorption materials and ceramics. The coarse slag can also be used to prepare catalyst or extract and recycle alumina and other high value utilization. The coarse slag contains certain kinds of heavy metals, which has certain environmental risks and restricts the comprehensive utilization of the gasification slag. Therefore, before the resource utilization of coarse slag, it is necessary to comprehensively analyze the enrichment and occurrence state of various heavy metals, and strictly control the environmental risk assessment, thus avoiding the secondary pollution caused by the resource utilization of coarse slag.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 317K]

  • Experimental study on carbon extraction from coal gasification fine slag by air classifier

    YANG Kai;ZHANG Qian;LUAN Chunhui;PENG Zeyu;HUANG Wei;State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology;College of Chemistry,Taiyuan University of Technology;

    The extraction and separation of residual carbon from coal gasification slag is the key to realize utilization of coal gasification slag. A large amount of carbon-ash complexes in the coal gasification slag formed under the conditions of high-temperature melting and complex reaction atmosphere. Grinding is an important method to dissociate the residual carbon in the slag. However, the particle size of the grinded slag is too small to use conventional separation process to extract carbon. Air classifier can achieve efficient separation of ultrafine particles by utilizing the centrifugal force and aerodynamic drag of different particles in the vortex to generate different directions of movement for classification. Based on this, a dry carbon extraction process by grinding the gasification slag was proposed and then the air classifier was used to separate residual carbon and ash. Through the design of uniform test and the regression analyses of the influencing factors, the optimal experimental conditions were obtained and the experimental results were verified. The results show that the airflow classification is influenced by the coupling effect of multiple factors, among which the frequency of the classifier and the frequency of the induced draft fan are the key factors affecting the carbon extraction effect, the optimum experimental conditions were the frequency of the classifier 175 Hz, the frequency of the induced draft fan 5 Hz, the frequency of the feed screw 5 Hz, and the opening of the secondary air valve 90°. The predicted value of the LOI of the carbon-rich products obtained under this condition(49.64%) is consistent with the experimental results(49.76%);Under the optimal conditions, the D_(av) of the carbon rich product obtained by airflow classification is 5.95 μm, can be used as a rubber reinforcement filler to replace carbon black and white carbon black; The calorific value is 16.73 MJ/kg, which can be fully used as fine powder fuel. Moreover, airflow classification can achieve good decarbonization effect of gasification slag, and the resulting decarburization slag has a loss on ignition of less than 10%, which is beneficial for its application in the field of building materials and other fields. The grinding crushing airflow classification method can achieve the separation of gasification slag, which is beneficial for its downstream utilization.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 587K]

  • Process of preparing high quality activated calcium oxide by flotation desiliconisation of calcium carbide slag

    ZHANG Kaixuan;ZHU Ganyu;LI Huiquan;MA Weiping;ZHANG Jianbo;MENG Ziheng;GUI Xiahui;National Engineering Research Center of Coal Preparation and Purification,China University of Mining and Technology;School of Chemical Engineering and Technology,China University of Mining and Technology;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 Chemi

    The recycling and reuse of calcium carbide slag for the preparation of high-quality activated calcium oxide(CaO) is one of the effective ways to achieve its efficient use, but the complex composition and high silicon content of calcium carbide slag restrict the product quality of the preparation of activated calcium oxide. Based on the distribution law and occurrence form of silica impurities in calcium carbide slag, the effect of flotation agents on the removal of silicon in calcium carbide slag were systematically investigated, a suitable desilication reagent for calcium carbide slag was obtained, the changes in elemental composition of calcium carbide slag and the changes in the properties of active calcium oxide products after roasting before and after flotation were studied, and a process route for the preparation of calcium oxide by flotation desilication coupled with roasting of calcium carbide slag was put forward. The results indicate that calcium hydroxide is the main component of calcium carbide slag, which also contains some silicon impurities such as silica and aluminosilicate. Through a reverse flotation desilication test combined with sodium hexametaphosphate of 400 g/t and dodecylamine of 125 g/t, the silica mass fraction of calcium carbide slag is reduced from 3.14% to 2.85%, and the calcium recovery rate reaches 87.9%. The calcium carbide slag after flotation separation of silica impurities could be completely converted into calcium oxide after roasting at 900 ℃, and the calcium oxide mass fraction in the product is 94.46%, the compressive strength is increased from 3.17 MPa to 3.87 MPa, and the metallurgical activity is increased from 341.6 mL to 385.5 mL, and the product performance is improved. The above research can provide reference for the recycling of calcium carbide slag.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 566K]

  • Preparation of porous carbon by K2CO3 activation of co-hydrochar of low-rank coal and sewage sludge and its adsorption performance for CO2 and SO2

    SONG Ruizhen;CHEN Yunxiao;YANG Xiaoyang;WANG Jiawei;WANG Baofeng;ZHAO Ruidong;Institute of Resources and Environment Engineering,Shanxi University;Engineering Research Center of CO2 Emission Reduction and Resource Utilization-Ministry of Education of the People′s Republic of China;Key Laboratory of Biofuels,Qingdao Institute of Bioenergy and Bioprocess Technology,Chinese Academy of Sciences;

    China has abundant reserves of low rank coal, and the material utilization of low rank coal is a major demand for the country. With the discharge of urban sewage sludge is rising, and the demand for resource utilization of high moisture sewage sludge is crucial. Hydrothermal carbonization of low-rank coal and sewage sludge can utilize the sulfur and nitrogen elements in raw materials effectively and prepare sulfur and nitrogen doped hydrochar. Hydrochar had relatively less abundant pores, and activation by activator can enrich its pore structure and prepare sulfur nitrogen co-doped porous carbon. In this paper, relatively mild K_2CO_(3 )was chosen as an activator for porous carbon preparation from co-hydrochars of sub-bituminous coal and sewage sludge, and the adsorption performance of porous carbon on CO_2 and SO_(2 )was also studied. The results showed that compared with those of the original hydrochars, the sulfur and nitrogen contents reduced after the activation modification by K_2CO_3, and the specific surface area of the porous carbon was increased from 23.92 m~2/g to 331.77 m~2/g, and the pore volume was increased from 0.07 cm~3/g to 0.23 cm~3/g. The prepared porous carbon had certain adsorption effect on CO_2 and SO_2. For the hydrochar obtained from co-hydrothermal carbonizaiton at the condition that the mass ratio of sub-bituminous coal to sewage sludge was 7∶3, and the hydrothermal carbonization temperature was 160 ℃, activated by K_2CO_(3 )at 700 ℃, the porous carbon has a CO_2 adsorption capacity of 1.56 mmol/g at 25 ℃; when the mass ratio of sub-bituminous coal to sewage sludge was 1∶1 and the hydrothermal carbonization temperature was 160 ℃, the activated hydrochar prepared had an adsorption capacity of 52.2 mg/g for SO_2 at an adsorption temperature of 120 ℃. The adsorption amount decreased with the increase of the hydrothermal carbonization temperature, and the adsorption performance of the porous carbon from co-hydrochar was better than that from the separate hydrochar for CO_2 and SO_2. The results may provide a theoretical basis for the clean and efficient utilization of low-rank coal and sewage sludge, as well as for the preparation of low-cost and efficient CO_2 and SO_2 adsorbent.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 1774K]

  • Preparation process and performance evaluation of gasification slag-based desulfurization activated coke

    PAN Wenjie;FAN Panpan;WANG Yang;GAO Yanchun;FAN Xiaoting;LI Xiangyu;BAO Weiren;WANG Jiancheng;State Key Laboratory of Clear and Efficient Coal Utilization,Taiyuan University of Technology;Key Laboratory of Coal Science and Technology (Taiyuan University of Technology),Ministry of Education,Taiyuan University of Technology;Shanxi Key Laboratory of Identification and Control of Atmospheric Complex Pollution,College of Environmental Science and Engineering,Taiyuan University of Technology;

    The problem of disposal of coal gasification slag produced in the coal gasification process is becoming increasingly serious. Residual carbon in the gasification slag developed pore structure and large specific surface area, which had the potential to prepare activated carbon and other high value-added carbon materials, and the full utilization of residual carbon could realize the sustainable use of carbon resources. After obtaining high quality separated carbon by water-mediated gravity separation, gasification residue-based desulfurization activated coke was prepared by coal blending method based on gasification residue separated carbon, which could realize the high value-added utilization of gasification residue. The effects of coal type, coal ratio, carbonization and activation process conditions on the structure and performance of desulfurization activated coke under the condition of high mixing ratio of gasification residue separated carbon was investigated by one-way and orthogonal experiments respectively. The study showed that the optimal coal composition of activated coke for gasification residue separated carbon at a blending ratio of 50% was 29% coking coal, 8% long-flame coal, and 13% coal pitch; The optimal carbonization conditions were as follows: heating rate of 5 ℃/min, carbonization temperature of 700 ℃ and carbonization time of 30 min; The optimal activation conditions were: activation temperature 900 ℃, heating rate 8 ℃/min, activation time 120 min, activated water volume 1.0 mL/(g·h). Evaluation of desulphurisation and regeneration performance of gasified slag-based desulphurisation activated coke using a fixed-bed reaction unit. Under the optimal formulation and process conditions, the desulfurization activated coke prepared in the kilogram experiments had an abrasion strength of 97.26%, a compressive strength of 696.3 N(measured value), an ash content of 11.66%, an iodine adsorption value of 378.78 mg/g, and a desulfurization value of 28.5 mg/g, which meet the requirements for desulfurization of coal particles. Technical specifications of A-type good grade of coal granular activated carbon for desulphurisation was satisfed and regeneration performance was good. The preparation of desulfurisation activated coke using gasification residue separated carbon as carbon source significantly reduces the production cost of activated coke, and at the same time provides a feasible way for the high value utilisation of gasification residue, which is of great significance for the reduction, resourcing and high value utilisation of gasification residue.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 496K]

  • Preparation of porous glass-ceramics from coal gasification fine ash slag

    ZHOU Li;REN Qiangqiang;CUI Ruifang;LI Linxuan;LI Wei;State Key Laboratory of Coal Conversion,Institute of Engineering Thermalphysics,Chinese Academy of Sciences;University of Chinese Academy of Sciences;

    Due to the lack of mature large-scale industrial disposal technology, a large amount of coal gasification fine ash has caused serious environmental pollution and resource waste. The treatment of coal gasification fine ash by fluidization melting can realize the separation of carbon and ash, and the modification and improvement of ash, so that ash can be transformed into glass phase slag rich in silicon and aluminum elements. Because of its special glassy interwoven structure, porous glass-ceramics have good mechanical properties and thermal insulation properties, so the idea of high value utilization of molten slag to prepare porous glass-ceramics was established. The effects of pre-curing time and sintering temperature on crystallization characteristics, pore structure and compressive strength of porous glass-ceramics were studied. The results show that the crystallization characteristics and pore structure of porous glass-ceramics are related to sintering temperature and pre-curing time. The higher sintering temperature can promote the crystal phase precipitation in the sintering process and strengthen the compressive strength of the porous glass-ceramics. The pre-curing time affects the network structure of the porous-glass embryo, resulting in different resistance to be overcome during crystal precipitation, which affects the type of crystal phase. When the pre-curing time is 30 min, the large pore size of the porous-glass embryo is easy to collapse during the process of sintering and crystallization. The compressive strength decreases with the increase of porosity and decreases nonlinearly with the increase of pore size. When the pre-curing time is 90 min, a good pore structure can be obtained. The compressive strength is influenced by the crystallization characteristics and the pore structure characteristics. When the sintering temperature is 900 ℃, the compressive strength can be strengthened, especially when the pre-curing time is 90 min, the compressive strength of the porous glass-ceramics is 3.77 MPa. At 700 ℃ and 800 ℃, whether the compressive strength increases is related to the pre-curing time. When the pre-curing time is 60 min and the sintering temperature is 900 ℃, a large number of crystals are precipitated, the porosity is 66.20%, the pore size is evenly distributed, and the compressive strength is 1.40 MPa.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 1410K]

  • Capacitive deionization of high N-doping carbon nanocages prepared by chemical vapor deposition

    XUE Yuhong;YIERXIATI·Dilixiatia;GULGINA·Pidamamatia;BAI Xiang;FU Guiyi;WEI Xianyong;HE Xiaoyan;ZHAO Hongguang;WANG Yanli;Key Laboratory of Chemistry and Chemical Engineering on Heavy-Carbon Resources,Yili Normal University;The Xinjiang Coal Gasification and By-Products Comprehensive Utilization Engineering Technology Research Center,Xinjiang Qinghua Energy Group Co.,Ltd.;

    Capacitive deionization(CDI) is a novel desalination technology that rapidly removes charged ions from water driven by electric field force. It has great potential in brine pre-concentration and reducing the energy consumption of zero liquid discharge desalination. However, the current CDI technology is limited by the low electro-adsorption active sites and uncontrollable pore structure distribution of porous carbon electrodes, resulting in low desalination capacity and charge efficiency, which hinders its further application. Therefore, highly active surfaces and structurally controllable N-doped carbon nanocages(N-CNC) were constructed by a chemical vapor deposition method using pyridine as a carbon source and alkaline magnesium carbonate as a templating agent to investigate their desalination properties. Through precise control of the carrier gas and pyridine quantities, the resulting N-CNC consists of 3-5 layers of graphitized carbon arranged in a hollow rectangular morphology. The average thickness of the outer wall ranges from 1 to 2 nm, with an impressive N content reaching up to 4.2%. Benefitting from its exceptional porous structure distribution and rich surface chemistry, N-CNC exhibits electrochemical behavior primarily contributed by its pseudo-capacitive properties. The desalination test results of the assembled N-CNC//N-CNC symmetric module using the single-pass desalination mode show that the salt adsorption capacity and charge efficiency are 21.8 mg/g and 82%, respectively, with low energy consumption of 0.71 Wh/g. Further treatment of coal chemical high-salinity water test show excellent anion absorption performance. Electric adsorption desalination capacity of Cl~-,SO_4~(2-),NO~-_3 are 33.4,20.5,8.9 mg/g, of which the selectivity ratio of Cl~-/SO_4~(2-) is as high as 5.1. This study provides a simple and controllable preparation method for N-doped carbon nanocage structure, which provides certain theoretical and technical support for the industrialization application of CDI concentrated industrial brine.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 980K]

  • Research progress on synthesis and modification of solid waste-based ZSM-5

    ZHANG Lihong;ZHAO Xuhui;GUO Yanxia;Key Laboratory of Efficient Utilization Technology of Coal Waste Resources,Institute of Resources and Environmental Engineering,Shanxi University;Shanxi Laboratory for Yellow River,Institute of Resources and Environmental Engineering,Shanxi University;

    In the industrial production process, a large amount of fly ash, red mud, and coal gasification slag is generated. The accumulation of these wastes not only occupies land but also severely damages the ecological environment and endangers human health. These three types of solid waste all contain silicon and aluminum elements, with relatively high contents and significant fluctuations in the silicon-to-aluminum ratio(molar ratio of silicon dioxide to aluminum oxide). ZSM-5(Zeolite Socony Mobil 5) is a type of zeolite molecular sieve with a wide range of silicon-to-aluminum ratios, featuring a unique pore structure and good stability, widely used in adsorption and catalysis. Utilizing silicon-aluminum-rich solid waste to prepare ZSM-5 is one of the important ways to achieve high-value and resource-efficient utilization. The general methods for activation and impurity removal pretreatment of silicon-aluminum-rich solid waste were systematically summarized. Based on the physical and chemical properties of fly ash, red mud, and coal gasification slag, the research progress on the synthesis of solid waste-based ZSM-5 and its metal modification, phosphorus modification, hydrothermal modification, and acid-base modification were reviewed. The effects of using solid waste as a silicon-aluminum source on the synthesis, structure, and performance of ZSM-5 were analyzed, highlighting the importance of regulating the silicon-to-aluminum ratio, removing and transforming impurity elements, and understanding the migration and transformation rules of major elements during the activation and impurity removal process. The impact mechanisms of different modification methods on the structure and performance of ZSM-5 were discussed. The distribution of silicon and aluminum in the framework and non-framework, the content and forms of impurity elements like iron and calcium, and the pore structure were emphasized as crucial factors influencing the modification outcomes. Through analyzing and discussing the existing problems and research status in the synthesis and modification of typical silicon-aluminum-rich solid waste-based ZSM-5, the future development should focus on the co-utilization of multiple sources of solid waste such as fly ash, red mud, and coal gasification slag, and the hydrothermal crystallization preparation of ZSM-5 under conditions without inorganic or no template agents. Efficient and precise modification of solid waste-based ZSM-5 is highlighted as the future direction.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 705K]

  • Preparation of gallium oxide by hydrolyzing dilute gallium sulfate from gallium enriched mother liquor of coal gangue

    ZHAO Zheng;WU Wenfen;HAN Yuqin;HOU Xinjuan;LI Shaopeng;ZHANG Jianbo;LI Huiquan;FENG Lili;School of Chemistry and Environmental Engineering,China University of Mining and Technology-Beijing;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 Chemistry and Chemical Engineering,University of Jinan;School of Chemical Engineering,University of Ch

    There are a lot of gallium resources in coal gangue in China, and the associated recovery and utilization of gallium has gradually become a research focus. Gallium metal was prepared by acid extraction of associated gallium and electrolysis of Ga-rich mother liquor, and the overall recovery of gallium was only 60%. With the increasing demand for gallium oxide, a new process for preparing gallium oxide by direct hydrolysis and precipitation of gallium-rich mother liquor was studied to reduce the preparation process of gallium metal and improve the comprehensive recovery rate of gallium products. However, the concentration of gallium ion in Ga-rich mother liquor is low, and the mechanism of hydrolysis and conversion by interaction with sulfate is not clear. In order to achieve efficient preparation of gallium oxide in low concentration Ga-sulfate mother liquor, the hydrolysis process and conversion mechanism were studied. The effects of reaction temperature, reaction time, stirring speed, pH of the system, initial gallium concentration and other factors on gallium precipitation rate and hydrolyzed products during hydrolysis of gallium in sulfuric acid system were investigated by orthogonal test. The morphologic changes of gallium hydroxy-coordination ions at different pH values were calculated by theoretical calculation, and the conversion mechanism of gallium during hydrolysis of gallium sulfate solution with low concentration was determined. The optimal gallium hydrolysis parameters were obtained by single factor test, and gallium oxide was prepared by calcination. The results show that the influencing factors of gallium hydrolysis are pH, reaction time, initial gallium concentration, stirring rate and reaction temperature. When pH<3.5, Ga~(3+) and Ga(OH)~(2+) in the solution are dominant, and the precipitate phase is gallium alingite under the affinity between sulfate and gallium ion. When 3.5<pH<6.5, gallium ions in solution coexist in many forms, and the precipitate phase is amorphous gallium hydroxide. When pH>6.5, Ga(OH)~-_4 is the main content in the solution, and the precipitate phase is oxidized from amorphous gallium hydroxide to hydroxyl gallium oxide. According to orthogonal and single factor experiments, the precipitation parameters of gallium sulfate solution are optimized as pH 5.0, initial gallium concentration 1 000 mg/L, reaction time 20 min, stirring rate 150 r/min, reaction temperature 20-25 ℃. The recovery rate of gallium is over 99.5%, and the precipitate phase is amorphous gallium hydroxide.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 750K]

  • Effect of the strong metal-support interaction on the hydrodeoxygenation of dibenzofuran

    WANG Dong;DU Zhenyi;State Key Laboratory of Clean and Efficient Coal Utilization,College of Chemical Engineering and Technology,Taiyuan University of Technology;

    As an important product of coal pyrolysis, coal tar has the characteristics of large output and wide application. The rational and efficient use of medium and low temperature coal tar can promote the clean and efficient conversion of coal resources. The removal of oxygen atoms from medium and low temperature coal tar is achieved by catalytic hydrodeoxygenation, which improves the hydrogen/carbon ratio and stability of the oil to obtain a high-quality fuel. Dibenzofuran was characterized by its high content and low reactivity, which was chosen as a model compound for the hydrodeoxygenation reaction study in this study. Modulation of Strong Metal-Support Interactions(SMSI) is widely used in heterogeneous catalysis field, but its effect on the hydrodeoxygenation is unclear. To investigate the effect of SMSI on the hydrodeoxygenation, nickel-titanium-zirconium layered double hydroxides were used as catalyst precursors, and Ni-based catalysts(denoted as Ni/mZrO_2@TiO_(2-x), m=0-0.5) with different SMSI were prepared for the hydrodeoxygenation reaction of the coal tar model compound dibenzofuran by varying the Zr ratio. Characterization by HRTEM, H_2-TPD and CO-pulse show that after high temperature calcination of the precursors, during the reduction process, part of the support is reduced to TiO_(2-x) to form an encapsulation layer on the surface of the Ni particles, and oxygen vacancies are simultaneously generated. As the Zr ratio increases, the SMSI strength decreases, resulting in a decrease in the encapsulation and oxygen vacancy content. The activity of the catalysts with different SMSI strengths was evaluated and it was found that the yield of the deoxygenated product increased from 60.7% to 94.8% and then decreased to 66.9% with decreasing SMSI strength(increasing Zr ratio) at 280 ℃ and 6 MPa. The Ni/0.4ZrO_2@TiO_(2-x) catalyst exhibites the highest deoxygenation performance, which show no decrease in activity after 5 cycles, indicating good stability. The results show that the hydrodeoxygenation performance of the catalyst is determined by the combination of encapsulation and oxygen vacancy vacancies by SMSI on the catalyst, with the degree of Ni encapsulation negatively correlated with the hydrogenation performance and the oxygen vacancy content positively correlated with the deoxygenation performance.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 1146K]

  • Coupling combustion technology of gas turbines flue gas and coal-fired boiler

    LAI Jinping;CHEN Hui;ZHANG Wenzheng;LIU Xin;LI Chaobing;HE Lucan;GE Ming;Guoneng Nanjing Electric Power Test & Research Limited;Yantai Longyuan Electric Power Technology Co.,Ltd.;

    To effectively utilize the exhaust heat of gas turbines, the feasibility of coupling combustion technology of coal-fired boilers and gas turbines flue gas was explored. Based on the basic theory of combustion, detailed calculations were conducted on the theoretical air volume, flue gas volume, burner nozzle velocity and other parameters of coal-fired boiler combustion after mixing with gas turbine flue gas. A coupling combustion technology scheme of gas turbine flue gas and coal-fired boiler was proposed.The influence of flue gas coupling on the combustion characteristics of coal-fired boiler was analyzed using full-scale numerical simulation technology.The numerical simulation results indicate that after flue gas coupling, the tangential diameter increases. As the initial temperature of pulverized coal flow increases, the volatile releases earlier, and the pulverized coal ignites earlier, the temperature of the boiler furnace decreases, and the heat absorption of the water wall decreases. The NO_x emission at the furnace outlet increases from 222.1 mg/m~3 to 229.5 mg/m~3, and the burnout rate decreases from 98.91% to 96.9%. Based on numerical simulation results, the energy consumption of the whole plant after flue gas coupling was analyzed, it can be concluded that although the coal consumption of boiler power generation increases by 2.0 g/kWh, the waste heat utilization efficiency of gas turbine flue gas has increased from about 80% to about 93%, representing a reduction of 10.98 g/kWh in the coal consumption of boiler power generation, so the energy consumption of the whole plant has decreased. The results indicate that coupling combustion technology of coal-fired boilers and gas turbines is feasible. After flue gas coupling, the gas turbine flue gas replaces most of the secondary air, significantly reducing the air flow through the air preheater, resulting in a significant decrease in the heat of the air preheater and a significant increase in the flue gas temperature. It is necessary to add a waste heat utilization device after the air preheater.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 447K]

  • Preheating and combustion characteristics of pine biomass particles

    ZHANG Jinyang;OUYANG Ziqu;DING Hongliang;SU Kun;Research Center of Fluid Machinery Engineering and Technolagy,Jiangsu University;Institute of Engineering Thermophysics,Chinese Academy of Sciences;University of Chinese Academy of Sciences;

    Pine biomass particles as a fuel source and integrated advanced self-preheating combustion technology was employed to achieve fluidized combustion within the furnace. The preheating modifications of woody biomass particles under different preheating temperatures were examined using a kilowatt level preheating combustion test rig. BET, SEM scanning electron microscopy and Raman spectral band comparison methods were employed to detect and analyze the specific surface area, total pore volume, nitrogen isothermal adsorption and desorption characteristics, particle morphology and other key physical property parameters of high temperature biomass semi-coke. The findings indicate that an increase in preheating temperature results in a noticeable rise in nitrogen adsorption amount, suggesting that the modified biomass semi-coke possesses a more developed pore structure. The depolymerization and devolatilization of pine biomass particles at high heating rates, combined with the analysis of carbon microcrystalline structure, result in the disruption of macromolecular carbon chains and the generation of small molecular volatiles, thereby enhancing reactivity. The modified high-temperature biomass semi-coke exhibits rapid attainment of stable combustion within the descending combustion chamber, with a remarkable combustion efficiency reaching 99% in terms of its combustion characteristics. In terms of NO_x emissions, the combustion temperature is maintained at 1 100 ℃ under all experimental conditions to prevent the formation of thermal NO_x. It is noteworthy that the concentration of NO_x emissions from pine biomass particles does not exhibit a linear relationship with preheating temperature. Specifically, at 842 ℃, the concentration of NO_x emissions peaks and then begins to decrease. Within the range of test temperatures, when the preheating temperature is set at 705 ℃, the concentration of NO_x emissions reaches its lowest value, namely 97.79 mg/m~3. In conclusion, for ensuring low NO_x emissions and high combustion efficiency in pine biomass after preheating combustion, this study recommends an optimal preheating temperature of 705 ℃.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 657K]

  • Inverted "N" type of power distribution in a 1000 MW opposed firing boilers

    GE Ming;LAI Jinping;JIANG Zhicheng;LYU Zhijia;WANG Jiayang;QIU Zhaohong;WU Yuxin;Guoneng Nanjing Electric Power Test & Research Limited;CHN Energy Lianjiang Port & Power Co.,Ltd.;Department of Energy and Power Engineering,Tsinghua University;

    Taking the coal pulverizing system of a 1 000 MW opposed firing boilers with side bunker layout as the research object, the distribution laws of powder quantity, fineness of pulverized coal and comprehensive resistance of powder tubes were analyzed. It is found that the distribution of powder quantity and pulverized coal fineness show an inverted "N" trend generally. The powder pipe with large amount of powder has a large fineness of pulverized coal while the pulverized coal fineness of the powder pipe with less powder quantity is small. The powder quantity and the pulverized coal fineness are positively correlated. The comprehensive resistance of powder tubes shows an “N” trend, which is negatively correlated with the powder amount and the fineness distribution of the pulverized coal. The powder distribution trend of powder tubes are caused by the different comprehensive resistance of powder tubes. The change of mill′s parameters does not affect this distribution law. The maximum deviation of powder amount on No.1 unit is 37.7% while the maximum deviation of powder amount on No.2 unit is 84.4%, which are far beyond the ±10% deviation required by the regulations. Different manufacturers of dynamic separators has different separation effects which result in different degrees of powder deviation. The characteristics of powder distribution require that the air distribution of burner must be adjusted accordingly. Measures such as increasing the swirl intensity, opening of the secondary air, turning off of the burning wind, and increasing of the operating oxygen are helpful to alleviate the partial combustion. For the burner with large amount of powder quantity, its internal and external secondary air volume and swirl intensity should be enlarged correspondingly. When the low load and odd number coal mills was running, the air-coal ratio of the coal mill with the largest deviation of the powder amount should be improved. A single unilaterally operated coal should be blended difficult-to-burn coal or reduces the separator speed to increase its flame center. After the combustion adjustment, the partial combustion problem of unit 1 is solved while the unit 2 still has slight partial combustion due to the large deviation of powder quantity. For the pulverizing system with excessive powder deviation, the problem of partial burning can be completely solved by the transformation of the pulverized coal side and the secondary air side. The characteristics of powder distribution and the optimization adjustment strategies provides a reference for the same type of units with partial burning.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 1427K]

  • Liquid phase emission behavior of gas diffusion layer surface in fuel cells

    LIU Shuai;YAO Xiaohang;ZHANG Libin;WANG Zhong;PEI Hao;School of Automotive and Traffic Engineering,Jiangsu University;Suzhou Automotive Research Institute,Tsinghua University;

    The two-phase distribution characteristics within the fuel cell flow channel are crucial for enhancing the fuel cell water management capability, and investigating the flow behavior of multiple liquid droplets on the surface of the flow channel can help to optimize the structure and operating conditions. The dynamic process of liquid water emergence from the gas diffusion layer(GDL) into the flow channel was simulated using the volume of fluid(VOF) method, and the effects of the gas flow rate inside the flow channel, the contact angle on the surface of the GDL, and the pore spacing on the water emergence process and flow behavior were investigated. The results show that the droplets undergo the processes of growth, separation, transport and collisional condensation within the GDL surface. The gas flow rate significantly affects the pressure drop and droplet separation period, with the increase of gas flow rate, the pressure drop increases, the droplet separation period decreases from 14.7 to 4.7 ms, and the water removal ability is significantly enhanced, and the high gas flow rate causes the unstable droplet morphology and flow condition.The wettability of the GDL surface modifies the surface tension, which in turn affects the droplet morphology and flow, and significantly influences the water coverage, and the average water coverage of the GDL surface is significantly affected by the increasing contact angle. The average water coverage on the GDL surface decreases from 20.03% to 9.01%; the water orifice spacing has a greater impact on the droplet collision cycle, small water orifice spacing when the droplets are growing in the process of condensation and large droplet splashing caused by a decrease in airflow velocity in the flow channel, the pressure drop and the water coverage on the GDL surface generates large fluctuations; large water orifice spacing, the velocity field in the flow channel is significantly affected by the previous droplet to obtain a larger velocity after collision is more likely to cause droplet splashing. At large water orifice spacing, the velocity field in the flow channel is significantly affected, and the previous droplet obtains a larger velocity, which is more likely to cause droplet splashing due to collision, resulting in a decrease in water coverage at the maximum water orifice spacing, from 16.84%(D=0.8 cm) to 14.69%(D=1.2 cm). The results provide theoretical guidance and technical reference for the optimization of flow channel surface contact angle, GDL pore distribution, air inlet conditions, etc., which can improve the water transport capacity and efficiency of PEMFC.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 879K]

  • Preparation of non-autoclaved aerated concrete with high content of coal gasification slag

    LI Ying;LI Hui;WU Feng;LI Taizhi;College of Materials Science and Engineering,Xi′an University of Architecture and Technology;Shaanxi Provincial Ecological Cement Concrete Engineering Technology Research Center;Xinjiang Transportation Science Research Institute Co.,Ltd;

    To realize the resource utilization of Coal gasification slag, aerated concrete is prepared with coal gasification slag as the main raw material, high salt wastewater as mixing water, supplemented by Ca(OH)_2 and NaOH. In the early stage, the coal gasification slag based cementitious materials were prepared by orthogonal test and single factor test. The proportion with the highest strength as the proportion of the aerated concrete matrix material was selected. The effects of hydrogen peroxide and Calcium stearate on the physical and mechanical properties and pore structure of aerated concrete were mainly studied, and the hydration products of aerated concrete under different curing temperatures were analyzed by microscopic detection methods such as XRD and SEM. The results show that based on the quality standard of coal gasification slag, 10% NaOH and 10% Ca(OH)_2 are added externally to the total amount of coal gasification slag, and the mixed water is high salt wastewater. At this point, the 28-day compressive strength of the coal gasification slag based cementitious material is the highest, reaching 68.8 MPa. Non-autoclaved aerated concrete is prepared by adding hydrogen peroxide as an air entraining agent and calcium stearate as a foam stabilizer to the cementitious material. As the content of hydrogen peroxide increases, the pore size of aerated concrete gradually increases and the number of connected pores increases, resulting in a decrease in both dry density and strength. After adding an appropriate content of calcium stearate, the pore distribution becomes more uniform and the pore shape tends towards a regular circular shape, resulting in a significant increase in strength. The content of hydrogen peroxide and Calcium stearate is 5% and 1.5% respectively, and the compressive strength of aerated concrete is the highest when the curing temperature is 80 ℃, reaching 2.9 MPa. In addition, the corresponding dry density is 617.2 kg/m~3. Micro analysis shows that the hydration products of high content coal gasification slag based aerated concrete are mainly C-S-H gel, C-A-H gel and zeolite. The hole wall is mainly composed of foil shaped C-S-H that intersects and overlaps with each other, with a small amount of randomly interwoven slender needle shaped C-S-H. These hydration products are cross-linked with each other, making the pore wall structure denser and contributing to the improvement of strength.

    2024 07 v.30;No.167 [Abstract][OnlineView][HTML全文][Download 714K]



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