2024年08期目次

  • Synthesis of Fe/Co/Ni based catalysts and NH3 cracking performance for H2 production

    HU Lihua;CHEN Jingye;TONG Jinming;HE Yong;XU Yanwei;WENG Wubin;WANG Zhihua;Everbright Environmental Technology Research Institute(Shenzhen) Ltd.;State Key Laboratory of Clean Energy Utilization,Zhejiang University;

    Hydrogen energy is considered to be the most promising alternative energy source to fossil fuels due to its advantages of efficient, clean and sustainable. As a kind of hydrogen storage material, ammonia has many advantages such as high hydrogen storage density and easy liquefaction, so hydrogen production by ammonia decomposition is an ideal method for hydrogen preparation. The development of highly selective, active and inexpensive catalysts for ammonia decomposition at low and medium temperatures is of great significance for the development and utilization of hydrogen energy. Ru-based catalysts are the most active single-metal catalysts for ammonia decomposition, but their costs are high, and transition metals such as Fe, Co and Ni are suitable substitutes for Ru. Meanwhile, the choice of catalyst carrier is a key factor in the preparation of efficient catalysts. A series of ammonia decomposition catalysts with γ-Al_2O_3, SiO_2, MgO and TiO_2 as the carriers and Fe, Co and Ni as the active components were prepared by the impregnation method, and the catalyst activity evaluation test was carried out in the ammonia catalytic cracking reaction platform at 400 ℃ to 700 ℃ and the air-velocity ratios of 18 000 h~(-1). On the basis of this, the synthesized catalysts were characterized by XRD, BET, SEM and TEM to investigate the effects of different activity combinations, carrier types, reaction temperatures and other factors on the ammonia catalytic cracking. The results show that the Ni/Al_2O_3 catalyst has the highest activity, and the ammonia decomposition rate reaches 91.67% at 18 000 h~(-1) and 600 ℃, and the complete decomposition of ammonia could be basically achieved at 650 ℃. The activities of Ni-based catalysts are overall higher than those of Fe-and Co-based catalysts, except for SiO_2 carrier. Characterisation reveales that a composite oxide structure formed by NiO and γ-Al_2O_3 existed in the Ni/γ-Al_2O_3 catalysts, while the larger specific surface area and pore volume of the γ-Al_2O_3 carriers are conducive to the improvement of the ammonia decomposition conversion rate.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 25504K]

  • Synergistic mechanism of elements inside of carbon peaking National Quality Infrastructure NQI based on Haken model

    HUA Tianyi;LONG Yan;WANG Bin;LIU Tao;ZHAO Yingna;School of Energy and Power Engineering,Huazhong University of Science and Technology;

    Under the background of "dual carbon", actively exerting the synergy of National Quality Infrastructure(NQI) elements such as metrology, standards, conformity assessment(certification and recognition & inspection and testing), which can provide important integrated quality basic support services for the first carbon peak in typical industries such as thermal power. The level of NQI synergy innovation and application technology in China can reach the international advanced level in individual regions and individual fields, but there are still obvious gaps in the overall, the systematic development of NQI synergy is insufficient, and the industrial support capacity of NQI synergy is weak. Therefore, in order to promote the synergetic development of NQI, an NQI coevolution model based on the Haken model was constructed to deeply explore the internal synergetic mechanism of NQI, reasonable normalization processing according to the internal order parameters of each identified element was carried out, and then the order parameters and key variables of NQI was identified, and the current synergetic development of the three elements of NQI in China was systematically analyzed. And NQI syenrgy support thermal power industry low-carbon development suggestions was gave. The results show that the order parameter of NQI synergetic development in China is the metrological factor, and the key variable is the standard factor. The development of the metrological factor plays a positive role in the NQI synergetic development, but the development of the standard factor has not formed a positive feedback effect on the development of NQI. The development of the three elements of NQI in China has been improved every year, among which the development of standards is the fastest, followed by metrology, and conformity assessment is the slowest. Metrology development is limited by the development of standards but it is also advancing. Conformity assessment requires the country to introduce more policies to promote the development of conformity assessment. There are regional differences in the development of NQI in China, especially the development of conformity assessment, which requires the state to introduce relevant policies to encourage the development of conformity assessment institutions in underdeveloped areas. Finally, in terms of NQI synergy support for low-carbon development of thermal power industry, it is necessary to strengthen the formulation of carbon emission metrology standards, strengthen carbon market data supervision, improve the transparency and credibility of carbon data, introduce relevant policies to encourage enterprises to adopt advanced carbon emission technologies, and actively participate in the construction of NQI.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 2518K]

  • Research progress of soft measurement technology optimizing carbon emission measurement of coal-fired power plants

    YAO Shunchun;LIU Zeming;LU Zhimin;GUO Songjie;XIE Zili;LI Zhenghui;HUANG Yongru;LI Longqian;LU Weiye;CHEN Xiaoxuan;School of Electric Power,South China University of Technology;Key Laboratory of Energy Efficiency and Clean Utilization in Guangdong Province;Guangdong Institute of Special Equipment Inspection and Research Shunde Branch;

    As a significant component of China′s energy structure, thermal power generation enterprises have long been the main source of carbon emissions in the country. With the global push for a low-carbon economy, those enterprisesare shifting from "dual control of energy consumption" to "dual control of carbon emissions." Under this backdrop, accurately measuring the carbon emissions of coal-fired power plants has become crucial. In carbon measurement for coal-fired power plants, flue gas flow impacts the accuracy of the online monitoring method. In contrast, coal consumption, carbon content in coal, and carbon content in fly ash jointly determine the reliability of the calculation method.Currently, most coal-fired plants only perform real-time monitoring of flow and coal consumption. However, direct, high-frequency, short-cycle monitoring of carbon content in coal and fly ash in harsh plant environments requires significant human and material resources and flow monitoring equipment is easily affected by the flue gas environment. Soft measurement technology, with its efficiency and low cost, provides an alternative method for monitoring key parameters in traditional carbon emission measurements.Firstly, this study reviews the establishment of a soft measurement model, including data preprocessing, auxiliary variable selection, model establishment, and model correction. Data preprocessing ensures data quality and improves modeling efficiency. Auxiliary variable selection enhances modeling efficiency by filtering out useful variables. The soft measurement model, based on mechanism and data-driven modeling, is key to predicting target variables. Model correction optimizes the model with actual data, improving prediction accuracy.Secondly, the study analyzes issues in monitoring flue gas flow, coal consumption, coal carbon content, and fly ash carbon content. It discusses the research progress and application of soft measurement technology for these parameters. Mechanism modeling, based on energy balance and mass conservation principles, has high interpretability and stability but is complex and less accurate. Data-driven modeling, using machine learning and data from distributed control systems(DCS) offers higher accuracy, but lacks transparency and generalization ability.Finally, this study summarizes and prospects the development and application of soft measurement technology in the field of carbon emission measurement. It provides suggestions for integrating the time-series structure of various plant parameters, the computational limitations of the plant itself, and the development of methods combining mechanism analysis and data-driven approaches. It summarizes the application scenarios of predictive CO_2 emission systems abroad and anticipates the application of such systems combined with soft measurement technology in domestic and international coal-fired power plants.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 8628K]

  • Applicability of data gaps imputation methods for monitoring flue gas carbon emissions

    CHEN Gongda;CHENG Guohui;CAI Rujin;ZOU Xiangbo;ZHU Wang;YE Ji;QIN Shiwei;TANG Shun;LU Weiye;Guangdong Energy Group Science and Technology Research Institute Co.,Ltd.;Guangzhu Power Generation Co.,Ltd.of Zhuhai Special Economic Zone;Guangdong Energy Group Co.,Ltd.;Guangdong Institute of Special Equipment Inspection and Research Shunde Testing Institute;

    In recent years, carbon measurement technology for flue gases has garnered increased attention. Nevertheless, due to the lack of comprehensive technical standards and systems in China, its formal implementation in the power generation industry remains limited, particularly concerning CO_2 monitoring data gaps. Effective methods for addressing CO_2 data gaps were investigated and three approaches were compared including retaining the last valid value before the gap, data conversion using oxygen based on default and median correction values, and utilizing the maximum carbon emission rate within the past 180 hours during long-term evaluations. The findings indicate that the maximum CO_2 volumetric fraction in actual fuel combustion varies under different load conditions, with distinct distribution patterns. For coal-fired units, the variability in the maximum CO_2 volumetric fraction is approximately 4%, with a median value of 18.67% that closely aligns with the default value. In contrast, for gas-fired units, the maximum CO_2 volumetric fraction exhibits two notable stages of variation, with a median value of 11.38%, differing by 0.12% from the default. Long-term evaluations show that the corrected method yields data most comparable to normal conditions, with monthly carbon emission deviations controlled within 1.5 tons, demonstrating high accuracy and applicability. However, while the 180-hour maximum value method can serve as an effective punitive management tool for carbon data, its widespread adoption may lead to overestimation of carbon emissions in international negotiations or transactions as flue gas monitoring becomes more prevalent in the coal-fired power sector.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 5502K]

  • Improved method for uncertainty evaluation of carbon measurement using flue gas direct measurement in thermal power unit

    HUANG Hui;LIU Jun;CUI Hongbin;LI Yanghai;LIU Li;HE Jun;XU Wanbing;WANG Nan;ZHOU Miao;XU Tao;XU Yan;State Grid Hubei Electric Power Research Institute;Hubei Fangyuan Dongli Electric Power Science & Research Limited Company;School of Energy Science and Engineering,Harbin Institute of Technology;State Grid Hubei Electric Power Co.,Ltd.;

    The carbon emission of the power industry accounts for more than 40% of the total carbon emission in China. Accelerating the improvement of the accurate measurement and uncertainty assessment method of carbon emission of thermal power plants plays an important role in the fine supervision of carbon emission of the power industry. Considering that the measuring performance and accuracy of the concentration, flow and other measuring instruments installed on the power plant site may change after long-term operation, using the factory accuracy of the meters to calculate the uncertainty cannot truly reflect the confidence level of the measurement. In this paper, an improved practical method for uncertainty assessment based on the periodic calibration results of the instruments was proposed. The method was used to evaluate the uncertainty of the online monitoring results of carbon emissions for a 660 MW power plant in Hubei Province, the contribution of uncertainty was analyzed, and optimization suggestions were proposed. The results show that the extended relative uncertainty of the carbon measurement results obtained by the direct measurement method is 8.282%(including factor k=2, confidence level 95%). With the exception of pressure, all other terms are dominated by class B uncertainty. Whether to consider the sensitivity coefficient and the choice of the evaluation method of Class B uncertainty will have a significant impact on the results. The main sources of carbon emission uncertainty are carbon dioxide concentration and flue gas flow measurement. The use of higher precision gas composition and flow measurement instruments, regular maintenance and calibration of measuring instruments, and optimization of measuring point layout in the flue can help reduce the uncertainty.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 10110K]

  • On-line measurement of temperature and CO2 concentration in flue gas based on deep learning coupled emission spectroscopy

    ZHOU Ying;LOU Chun;MA Xiaochun;State Key Laboratory of Coal Combustion,School of Energy and Power Engineering,Huazhong University of Science and Technology;Xinjiang Uygur Autonomous Region Research Institute of Measurement & Testing;

    Based on low-resolution infrared spectroscopy acquisitionand deep learning computational methods, an online detection method for flue gas temperature and CO_2 concentration is proposed. The gas spectral radiation model was used to calculate the training data, the distribution of flame flue gas temperature and CO_2 concentration was inverted based on a multi-layer perceptron(MLP) neural network. Results show that the inversion errors of the MLP neural network model for temperature and CO_2 and H_2O volume fractions are less than 1%, and the prediction accuracies are all greater than 94.5%, which has good generalization and prediction capabilities. A set of on-line detection device for flue gas temperature and CO_2 concentration based on deep learning coupled with emission spectroscopy was established, and the ethylene diffusion flame and C_2H_4/NH_3 partially premixed flame were investigated. The measurement results of flue gas temperature and CO_2 volume fraction for the ethylene diffusion flame were consistent with the simulated flame results, which verified the feasibility of the online detection method based on deep learning coupled with emission spectroscopy. Changing the ammonia doping ratio of the partially premixed flame and analyzing the temperature and CO_2 concentration changes of the gas at different heights above the central axis of the flame, results show that the flue gas temperature at the same height increases with the increase of the doped ammonia, and the CO_2 volume fraction shows a tendency to increase and then decrease sharply. The proposed method can detect the changes of temperature and CO_2 more sensitively, which can be used for combustion diagnostic studies of many kinds of flames, and also has some potential applications in the online detection of carbon emissions in power plants.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 16789K]

  • Optimization of greenhouse gas accounting methods applicable to biomass direct-coupled coal power generation processes

    ZHAO Yue;LI Xiaoshan;ZHANG Liqi;ZHAO Yongchun;School of Energy and Power Engineering,Huazhong University of Science and Technology;

    Direct coupled combustion of biomass and coal for power generation has gained widespread attention as a key technology option for reducing carbon emissions in the coal power sector. Driven by Carbon Peaking and Carbon Neutrality Goals, the accurate quantification of greenhouse gas(GHG) emissions from biomass-coupled power production processes can effectively improve the accuracy and consistency of carbon emission data in the power generation industry and ensure the development of the domestic carbon trading market in a more fair and stable direction. Carbon accounting methods for biomass-coupled coal generating units at home and abroad were first introduced. Then the biomass direct-coupled generating unit greenhouse gas accounting boundary, calculation method and the selection principle of accounting parameters were proposed with reference to the experience of European and American countries. The results show that, compared with the current accounting method, the GHG accounting method based on biomass directly coupled with coal power generation has some differences in the accounting boundary, accounting scope and calculation method. For the accounting boundary, it is necessary to add N_2O emissions from the fuel combustion process and indirect carbon emissions from new equipment resources. The common biomass fuels were evaluated to see if zero emissions could be considered, and common biomasses was found, such as straw, municipal solid waste, and forest residues, met the GHG emission reduction requirements within the optimal economic transportation radius of the biomass in each province, and zero emissions within the reasonable transportation range(48 km) could be considered. In the calculation method, fuel consumption was recommended to select the measurement method according to the carbon emission stratification, the carbon oxidation rate could be directly selected as the default value of 99% in the case of small-ratio blending, carbon emission brought by the desulfurization link calculation is recommended, and the N_2O accounting was needed for the circulating fluidized bed combustion temperature under the working condition of 1 123 K.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 9348K]

  • Carbon emission performance calculation and impact analysis of coal-fired power plants

    LI Peng;ZHOU Weiqing;BAI Xiaoxuan;CHEN Chuanmin;LIU Songtao;SUN Tianxiang;Jibei Electric Power Research Institute,State Grid Jibei Electric Power Co.,Ltd.;Department of Environmental Science and Engineering,North China Electric Power University (Baoding);

    To improve the accuracy and temporal resolution of carbon emission accounting for thermal power plants, Aspen Plus in conjunction with mathematical models was used to account for carbon emission performance and analyze the effects of load, flue gas temperature, air distribution volume and coal composition on carbon emission performance. The results indicated that the carbon emission performance of a certain coal-fired power plant′s 200 MW unit in fuel combustion was 674.02 g/kWh, while the performance based on calcium desulfurization was 3.10 g/kWh. Compared with the measured method, the deviation of carbon emissions calculated in this study was only 4.07%,validating the rationality of the accounting method. Regarding the analysis of factors affecting carbon emission performance, under 30%,50%,and 75% load of a 200 MW unit, carbon emission performances increased by 1.52%,3.86%,and 6.92% respectively compared to full load. The impact of flue gas temperature on carbon emission performance was relatively weak; increasing from 75 ℃ to 145 ℃ resulted in only a 0.02% increase in carbon emission performance. The carbon emission performance first increased and then decreased as the air distribution increased. The carbon emission performance at 5.00×10~5,6.80×10~5 and 8.00×10~5 kg/h was 682.74,673.48 and 679.20 g/kWh, respectively. In addition, the carbon emission performance of coal species with low carbon content and high low calorific value was relatively low, and the carbon emission performance of coal powder moisture increase was slightly improved.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 15646K]

  • Correction method of the recommended value of carbon content per unit calorific value of blast furnace gas based on measured data

    WAN Yingfeng;LI Qiujun;PAN Shuting;FAN Min;Sinosteel Wuhan Safety & Environmental Protection Research Institute Co.,Ltd.;

    The carbon emission accounting method of the iron and steel industry is based on the emission factor method provided by GB/T 32151.5-2015 Greenhouse gas emissions accounting and reporting requirements-Part 5: Steel production enterprises. The carbon content per unit calorific value(C_C), as an index to characterize the carbon content of combustible substances per unit calorific value, is an important influencing factor for calculating carbon emissions by emission factor method. Previous studies on carbon emissions in the iron and steel industry mainly focused on the differences between various accounting methods, but there are few studies on the accuracy of the recommended value of carbon content per unit calorific value. In order to study the influence of the carbon content per unit calorific value of combustible substances on the calculation of carbon emissions of blast furnace gas, a by-product gas of ironmaking process in the iron and steel industry was selected as the research object, and the measured values of blast furnace gas C_C under different components(CO and CO_2) were calculated based on the measured data of various indicators of blast furnace gas in a steel mill. The changes of measured parameters such as the measured calorific value of blast furnace gas at low level, the measured value of C_C of total carbon component, and the measured value of C_C in combustion process were analyzed. Combined with the current situation of the widespread application of the emission factor method, based on the fluctuation of the measured value of C_C, three methods for correcting the recommended value of C_C to C_C in the combustion process were proposed. The deviation between the corrected value and the measured value under their respective applicable conditions, was less than 5%. Finally, the relevant statistical data of the blast furnace ironmaking process of the steel mill in 2021 was used. The calculation results of the carbon emissions of the blast furnace body before and after the correction of the C_C recommended value of blast furnace gas were compared and analyzed. The carbon emissions of the blast furnace body before the correction were-0.19 tons of CO_2 for every tons of iron, and the carbon emissions of the blast furnace body were 0.415 tons of CO_2 for every tons of iron after the correction, which was consistent with the real carbon emissions. The results show that when calculating the carbon dioxide emissions of blast furnace in the iron and steel industry, the carbon content per unit calorific value of blast furnace gas is corrected by using the measured mean, the correction coefficient w(CO)/[w(CO)+w(CO_2)] and w(CO)-C_(com) fitting curve, and the calculation results are consistent with the actual results.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 1431K]

  • Cost analysis of chemical looping coal-fired power plant based on a double factors learning curve model

    YE Ji;CHEN Chuangting;HUANG Hui;KUANG Cao;HONG Yuwu;XU Zuwei;LIU Jingkang;ZHAO Haibo;Guangdong Energy Group Science and Technology Research Institute Co.,Ltd.;Guangdong Energy Group Co.,Ltd.;School of Energy and Power Engineering,Huazhong University of Science And Technology;

    Chemical looping combustion(CLC) is regarded as one of the most promising technology options for carbon dioxide capture, utilization and storage. However, there is no relevant study on dynamic cost prediction and systematic cost reduction trend analysis of CLC technology. A techno-economic analysis of CLC retrofitted coal-fired power plant(2×350 MW) was carried out, and it was found that the power generation cost was 419.595 ￥/MWh. The CO_2 avoidance cost and CO_2 capture cost were 96.142 ￥/t and 85.847 ￥/t, respectively. In order to predict the change trend of the cost of CLC power plant, a new learning rate model was proposed and a two-factor learning curve was obtained. Then the medium/long term costs of CLC technology was predicted by considering three technology development scenarios: high speed, baseline and low speed. The results show that as the cumulative installed capacity of the power plant and the cumulative research and development investment are improved, the power generation costs of the power plant are gradually reduced. In the benchmark scenario, the cost of power generation has dropped to 311.767 ￥/MWh, with a drop of over 100 ￥/MWh. Under the high-speed development scenario, the unit investment cost of CLC power plant will be reduced to 2 593.789 ￥/kW, which is close to the level of traditional coal-fired power plants.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 6223K]

  • Screening and engineering verification of a low energy consumption CO2 mixed amine absorbent

    XU Dong;HUANG Yan;SONG Junchao;SHI Xiaohong;WANG Tao;ZENG Weiqiang;ZHANG Shuai;LI Shuifei;FANG Mengxiang;GAO Xiang;China Energy Corporation New Energy Technology Research Institute Co.,Ltd.;Guoneng Jinjie Energy Co.,Ltd.;State Key Laboratory of Clean Energy Utilization,Zhejiang University;Key Laboratory of Clean Energy and Carbon Neutrality of Zhejiang Province,Zhejiang University;Qingshan Lake Energy Research Base,Zhejiang University;

    With the increasingly serious greenhouse effect, chemical absorption method, as the most promising technology for decarbonization of coal-fired flue gas, has received wide attentionof China and abroad. The development of absorbents with low energy consumption, high stability and easy engineering application is a research hotspot at present. An absorbent scheme was proposed with high capacity and low energy consumption tertiary amine as the main absorbent, high kinetic primary amine and high stable cyclic amine as the auxiliary agent. An engineering development system has been formed, ranging from the selection of laboratory formula, the matching of 100 standard square meters per hour pilot energy-saving process to the optimization of the operation of 10 000 standard square meters per hour scale industrial devices. Through the quick screening of absorbents was carried out through bubbling absorption experiment and absorption-regeneration cycle experiment, and an absorbent formula with excellent performance was obtained through primary screening. Further, the energy-saving process was optimized and its operation stability was verified through the test of 200 m~3/h pilot plant and 10 000 tons of industrial plant. The test results show that the CO_2 removal rate of the CEU type absorbent developed in this study reaches 90%, and the optimal energy consumption reaches 2.42 GJ/t CO_2, and it has completed 700 hours of stable operation on the industrial device.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 4679K]

  • Experimental study of electrocatalytic CO2 reduction by nano-SnO2 based on stacked electrolytic reactor

    WEI Shuzhou;TAN Shuting;XIONG Zhuo;XU Zuwei;ZHAO Yongchun;ZHANG Junying;Sanhe Power Generation Co.,Ltd.;Utilization and Storage (CCUS) Technology for Coalbased Energy,National Energy Research and Development Center of Carbon Capture;Hebei Province Coal-fired Power Station Pollution Prevention and Control Technology Innovation Center;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;

    The electrocatalytic reduction of carbon dioxide(CO_2) using new energy and electrical energy can convert CO_2 into value-added chemicals while reducing carbon emissions, which has broad application prospects. Among the various reduction products, formic acid(HCOOH) is easy to store and transport, with a high storage density of hydrogen. Tin oxide(SnO_2) electrocatalytic materials are low-cost and less toxic, while SnO_2 is highly selective for HCOOH when used for electrocatalytic reduction of CO_2.In the industrialization of electrocatalytic reduction, a reasonable electrolytic reactor structure is of great significance. To explore a more reasonable electrolytic reactor structure, this paper proposes a homemade multilayer stacked electrolytic reactor, in which SnO_2 nanoparticles prepared by flame spray pyrolysis method are used as electrocatalysts for electrocatalytic reduction of CO_2.The effects of parameters such as cathode-anode spacing, electrolyte flow rate, electrolyte concentration and the number of electrode stacks on the electrocatalytic performance of the electrolytic cell were investigated. The experimental results show that: the closer the cathode-anode distance is, the lower the electrical energy loss is, and the catalyst has better catalytic performance; the flow rate of the electrolyte has no significant effect on the reduction performance of the catalyst, but when the flow rate is too fast, the current density of the reaction produces a more drastic fluctuation. When the electrolyte concentration was less than 1 mol/L, the selectivity of the catalyst for HCOOH increased with the increase of the electrolyte concentration, whereas the selectivity of the catalyst for each product stabilized at the electrolyte concentration of more than 1 mol/L. The current density decreased slightly when the electrodes were placed in stacks, but the overall Faraday efficiency and the Faraday efficiency of HCOOH both increased, and the hydrogen precipitation reaction was suppressed more significantly. The charge transfer resistance and diffusion resistance were reduced when using a stack electrolytic reactor. The optimum Faraday efficiency for HCOOH of SnO_2 under stack conditions reaches 37.53% and the total Faraday efficiency reaches 75.83% with the cathode-anode spacing of 10 mm, the applied potential of-1.2 V vs. RHE, and the KHCO_3 concentration of 1 mol/L. The results indicate that the catalytic performance of the catalyst and the selectivity of the target products can be enhanced by using a stacked electrolytic reactor.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 7316K]

  • Numerical study on the combustion and emission characteristics of premixed NH3/H2 jet flame

    LIU Xiangtao;WANG Guochang;SI Jicang;LI Pengfei;MI Jianchun;College of Engineering,Peking University;State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology;Marine Engineering College,Dalian Maritime University;School of Energy and Power Engineering,Huazhong University of Science and Technology;

    The utilization of fossil fuels has propelled the advancement of human society; however, it has also caused global climate change, posing a threat to the survival and development of humanity. In this context, ammonia and hydrogen, as zero-carbon fuels, have attracted much attention. However, their combustion utilization faces numerous challenges. MILD combustion is a new combustion technology that may achieve clean and efficient combustion of NH_3/H_2 blended fuel, but research in this area is currently very limited. The combustion and emission characteristics of a premixed NH_3/H_2 jet flame was thoroughly investigated by numerical simulation. Specially, the hydrogen proportion(X(H_2)_F) and jet equivalence ratio(Φ_J) were varied, and a detailed analysis on temperature rise, reaction zone size, lift-off height, radical concentrations, and NO_x emissions was conducted. Results indicate that the addition of a small amount of H_2 significantly enhances the stability of ammonia flame, lowers the auto-ignition temperature, and eliminates flame lift phenomenon. Moreover, an increase in X(H_2)_F elevates the combustion temperature, accelerates the production of H,O, and OH radicals, thereby leading to a transition in the combustion regime from MILD to high-temperature combustion. Under fuel-rich conditions and low X(H_2)_F, significant amounts of NH_3 decompose into H_2 prior to main combustion reactions, resulting in high combustion temperatures. As for NO_x emissions, N_2O and NO are the dominant sources, while NO_2 is negligible. Generally, the emissions of N_2O and NO first increase and then decrease with increasing X_(H2, F). Moreover, when X(H_2)_F is low, the peak concentrations and emissions of N_2O and NO are comparable. However, as X(H_2)_F increases, the temperature rises, leading to the decomposition of N_2O, with NO becoming the primary source of NO_x emissions. Furthermore, under fuel-rich conditions, the combustion temperature, OH concentration, and the entrainment of jet to the coflow O_2 collectively influence the NO_x emission.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 27164K]

  • Optimization of combined wind-solar-thermal-storage system considering the uncertainty of renewable energy output

    SONG Zhihui;TIAN Junjian;NI Zhanshi;LIN Qizhao;School of Information Engineering,Guizhou Open University(Guizhou Vocational Technology Institute);Department of Thermal Science and Energy Engineering,University of Science and Technology of China;

    The combined dispatching and operation of wind-solar-thermal-storage is an important path to help the thermal power industry achieve carbon peaking and carbon neutrality goals. In order to cope with the impact of renewable energy output uncertainty on the power system, a set of uncertain parameters of wind power and photovoltaic power output was constructed to minimize the total operating cost as the optimization goal, and a two-stage robust optimization model was established to optimize the scheduling of the combined wind-solar-thermal-storage system. The uncertainty optimization problem was decoupled into a first stage involving deterministic parameters and a second stage involving uncertain variables. In the first stage, the start-up and shutdown state of thermal power units and charging and discharging state of energy storage equipment were solved based on the predicted output of renewable energy. In the second stage, as a flexible regulation stage, the output power of each equipment under the worst scenario after disturbance occurs was solved, and the column constraint generation algorithm was used to calculate with examples. The results show that the model can effectively smooth the net load fluctuation and relieve the peak load pressure of thermal power units through reasonable energy abandonment and energy storage. Compared with the deterministic optimization model, the increase in operating cost obtained from the solution of the uncertainty optimization model indicates that the robust optimization considering the uncertainty of renewable energy has a higher conservative degree. At the same time, the greater the deviation of renewable energy output, the smaller the increase in operating cost compared with the deterministic optimization, effectively reducing the interference of renewable energy output deviation on system economy.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 14873K]

  • Effect of spectral response curves on accuracy of combustion measurement techniques based on two-color method

    HAN Lei;CHENG Yong;ZHU Ningjing;WANG Zhe;HUANG Zhifeng;School of Power and Mechanical Engineering,Wuhan University;

    The two-color method based on CCD cameras is widely used for measuring the combustion temperature field and soot volume fraction field, playing an important role in understanding combustion laws and mastering combustion states. However, most of the existing work ignores the spectral response characteristics of CCD cameras and regards the detection signals of each channel of the CCD camera as the radiant energy of the flame at a specific wavelength, which brings errors to the measurement results of combustion temperature and soot volume fraction. In this work, an ethylene/air laminar diffusion flame was considered. The impact of various parameters of the spectral response curves(SRC), such as shape, half width, and asymmetry, on the accuracy of reconstructed flame temperature and soot concentration were analyzed. It is found that the influence of SRC shape and bandwidth on the reconstruction accuracy is small, the reconstruction errors of the temperature field are all below 1% without considering signal error. If the SRC is asymmetric or the center wavelength is inaccurate, there are relatively larger errors in the reconstruction results, and the errors of the temperature field may achieve 2.4% without considering signal error. Through experimental measurement of ethylene laminar diffusion flame by a CCD camera, it is found that there is a significant deviation between the measurement results using the center wavelength and the actual SRC, and the maximum temperature and maximum soot volume fraction errors are 4.74% and 16.4%, respectively.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 36046K]

  • Analysis of low carbon potential of biomass reforming gas injection-oxygen blast furnaces

    MAO Wenchao;HUANG Zhihui;ZHANG Zewu;LI Xiaoshan;XIONG Zhuo;ZHANG Liqi;State Key Laboratory of Coal Combustion,School of Energy and Power Engineering,Huazhong University of Science and Technology;

    China′s iron and steel industry is dominated by the long blast furnace-converter process, with primary energy consumption mainly pulverized coal and coke. The large amount of fossil energy consumption leads to high carbon emissions, 70% of which are generated by the blast furnace ironmaking process. To realize the "Dual Carbon" targets earlier, it′s urgent to develop low-carbon ironmaking technologies to reduce the energy consumption and CO_2 emissions from the blast furnace process. In this study, a biomass reformed gas injection-Oxygen Blast Furnace(BRGI-OBF) process was proposed. In this process, the gasifier process parameters were optimized, and biomass reforming was adopted instead of pulverized coal reforming. Thus, the reformed gas meets the blast furnace′s hydrogen-rich smelting demand and reduces fossil fuel consumption. Combined with carbon capture in the oxygen-enriched combustion of blast furnace gas, CO_2 in the end-stream flue gas can be greatly enriched, thus realizing low energy consumption and low carbon(negative carbon) emission of the blast furnace. In order to analyze the low-carbon potential of the BRGI-OBF process, a model of the BRGI-OBF process was first constructed by the chemical process analysis software Aspen Plus. Then, the effects of the heat input to the gasifier and the type of biomass on the process performance were analyzed. Furthermore, based on the calculated process parameters, the traditional blast furnace process and the top gas recycle-oxygen blast furnace(TGR-OBF) process were horizontally compared in terms of energy consumption and carbon flow by applying the energy consumption calculation method of the blast furnace ironmaking process. The results show that supplying appropriate heat to the gasifier effectively reduces pulverized coal consumption by up to 124.2 kg/t(per metric ton of hot metal) and increases the amount of recycled gas. Notably, different biomass types have a significant effect on the amount of biomass and the composition of reformed gas. When poplar semi-coke is used for reforming, 204 kg/t of poplar semi-coke would be consumed with up to 29.91% of H_2 in the reformed gas, fulfilling the needs of hydrogen-rich smelting. In addition, the BRGI-OBF process significantly improves the energy structure with a fossil energy share of about 55%, reducing the consumption of pulverized coal and coke by 17.6% and 29.3%, respectively, compared to conventional blast furnaces. With the process coupled to oxygen-enriched combustion carbon capture technology, 372.6 kg/t of carbon exists in the end stream in the form of highly concentrated CO_(2 )(>90%) that can be easily compressed and captured. Deducting the carbon emission from poplar semi-coke, the total carbon emission would be-109.9 kg/t, which is equivalent to 403 kg of additional CO_2 capture per ton of iron produced. This process can realize the carbon negative technology of biomass + CCS, which significantly support the iron and steel industry to achieve deep decarbonization.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 33538K]

  • Advances in catalysts and project progress for CO2 hydrogenation to methanol

    YE Zhiyuan;RAO Na;XIA Changyou;LIU Shuo;LIANG Xi;Guangdong CCUS Centre;Institute of Energy Research,Jiangxi Academy of Sciences;Ningxia Electric Power Design Institute;University College London;

    Methanol is a crucial organic raw material and fuel, particularly in the context of the climate and energy crisis. Developing a methanol economy is crucial to promoting a green, low-carbon transformation of the chemical, energy, and transportation sectors while ensuring a secure energy supply. A comprehensive overview of the CO_2 hydrogenation process routes to methanol was offered, including an analysis and summary of the performance of copper-based, indium-based, solid solution, and noble metal catalysts. The data show that the reaction conditions of all four types of catalysts are concentrated at 200-300 ℃ and 1.5-5.0 MPa. While copper-based catalysts were the most widely studied and applied, with a median CO_2 conversion and methanol selectivity of 13.6 and 69.2,respectively,indium-based catalysts and solid solution catalysts have comparable CO_2 conversion and methanol selectivity but exhibit better stability. The extreme values of CO_2 conversion and methanol selectivity for noble metal catalysts vary significantly, with limited data related to stability. Solid solution catalysts demonstrate exceptional catalytic performance and stability under industrial conditions, making them a promising catalyst type for large-scale application in the future. Furthermore, this paper provides an overview of existing CO_2 hydrogenation to methanol projects and technical routes both domestically and abroad. The number of carbon dioxide hydrogenation to methanol projects is increasing, with production capacities ranging from 4 000 t/a to 200 000 t/a. Industrial emission source CO_2 capture devices as the carbon source and electrolytic water as the primary source of hydrogen were primarily relied on. As the goal of carbon neutralization becomes increasingly critical, the CO_2 hydrogenation to methanol technology becomes even more vital. Therefore, it is recommended that research and development of CO_2 hydrogenation to methanol catalyst technology receive greater support, as well as industrial application of the project.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 1611K]

  • Preparation of hierarchical nano-SAPO-11 zeolites as catalysts for the synthesis of 2,6-dimethylnaphthalene

    ZHANG Xiaohua;ZHANG Pu;JI Lin;JIANG Lejie;SONG Yanping;WEI Haiguo;ZENG Qingfeng;YE Runping;FENG Gang;PetroChina Planning and Engineering Institute;Petro China Refining,Chemicals & New Materials Company;Liaohe Oilfield Oil and Gas Gathering and Transportation Company;School of Chemistry and Chemical Engineering,Nanchang University;

    As a microporous zeolite, SAPO-11 zeolites usually have a large particle size, and SAPO-11 with a small particle size has shorter pores, which facilitate better diffusion of molecules and thus enhance catalytic activity. However, this also leads to poorer stability. How to further synthesize hierarchical nano-SAPO-11 zeolites on the basis of hydrothermal method is a great challenge. Based on the hydrothermal method, SAPO-11 zeolites were prepared by aging treatment with the precursor gel. Among them, the SAPO-11 zeolites prepared by stirring aging treatment at 80 ℃ has the smallest crystal size. It can be seen by SEM that the S11-80 ℃-stirring zeolite show a uniform nanorod-like structure, these nanorods have a diameter of about 500-700 nm and a length of about 2-4 μm. The N_2 adsorption-desorption isotherms and pore size distribution curve reveal that the SAPO-11 zeolite treated by aging has a larger specific surface area compared to conventional SAPO-11. Specifically, zeolites prepared by agitation aging show a higher specific surface area and pore volume for micropores, but lower values for mesopores compared to those prepared by static aging. The NH_3-TPD curves characterization of the acidic properties shows that all SAPO-11 zeolites synthesized with aging treatment have reduced acidity. 2-Methylnaphthalene(2-MN), which is mainly derived from coal tar, can be used to prepare 2,6-dimethylnaphthalene(2,6-DMN), and then be used to synthesize high-end polyester. Therefore, the above-mentioned hierarchical nano-SAPO-11 zeolites were applied to catalyze the alkylation reaction of 2-methylnaphthalene. The results show that the SAPO-11 zeolites prepared by aging treatment have 77.8% initial conversion of 2-MN, 20.4% initial selectivity, 1.13 molar ratio of 2,6-DMN/2,7-DMN, and the highest selectivity of 2,6-DMN of 39.9% at the 4th hour of reaction. The shape selection catalytic mechanism of SAPO-11 molecular sieve was revealed by series characterization.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 4166K]

  • Review of bench and pilot-scale testing for calcium looping capture of carbon dioxide

    WANG Changqing;TAN Yuyao;LIN Mingwei;LIU Wenqiang;DENG Lidan;ZHOU Zijian;XU Minghou;State Key Laboratory of Coal Combustion and Low CarbonUtilization;

    CO_2 generated by coal-fired power plants could exacerbate the greenhouse effect, so achieving greenhouse gas emission reduction goals is crucial. Carbon capture technology has been identified as a key measure to reduce carbon emissions in the power sector. When mature technologies such as amine scrubbing and oxygen combustion technology are integrated into power plants, efficiency penalty could result in high efficiency penalty(8.0%-12.5%). For this reason, to minimize efficiency penalties and related increased power costs, new carbon dioxide capture technologies have been developed. The calcium looping process is a promising technology that could reduce efficiency penalty to 7%. Due to the high cost of capital, cost-effective technologies with commercial scale have not yet been developed. Before designing and constructing commercial scale devices, it is necessary to have a deep understanding of the system behavior under various operating conditions to optimize process parameters and evaluate feasibility. An overview of the available bench-scale and pilot-scale testing facilities worldwide. Characteristics and operating conditions of the testing equipment were summarized, key experimental results were also extracted, indicating that the feasibility of the CaL process has been widely studied in bench-scale and pilot-scale facilities ranging from 1 kW_(th)-1.9 MW_(th). In these CaL systems, the operating temperature range of the carbonator is 600-700 ℃, and the operating temperature of the calciner is 800-1 000 ℃. The CO_2 entering the carbonator comes from the power plant and can achieve CO_2 capture efficiency of over 90%. In addition, adjusting operational design parameters such as CO_2 inlet concentration, carbonation or calcination temperature, etc. will affect CO_2 capture efficiency. In summary, these results provide valuable operational data for the development of future large-scale platforms, which will also be the key to expanding and deploying this technology in future development.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 11187K]

  • Research progress on methods and technologies for enhancing flotation separation of fine coal slime

    WANG Xuexia;YU Mei;WANG Yemin;MA Chao;BU Xiangning;Department of Mining Engineering, Shanxi Institute of Technology;Key Laboratory of Coal Processing and Efficient Utilization (Ministry of Education),China University of Mining & Technology;School of Chemical Engineering and Technology,China University of Mining & Technology;

    The main bottleneck restricting the efficient flotation recovery of fine coal slime is the low mineralization efficiency of particles and bubbles caused by the properties of fine coal slime itself, but the influence of factors such as clay mineral entrainment pollution, foam properties, and collector performance cannot be ignored. To understand the latest research progress on methods and technologies for enhancing flotation separation of fine coal slime, firstly, the reasons for the difficulty in flotation separation of fine coal slime were introduced. Secondly, seven aspects including increasing apparent particle size, reducing bubble size, strengthening flow field regulation, optimizing collector performance, improving flotation equipment, innovating flotation processes, and pretreating slurry were reviewed comprehensively. Finally, the advantages and disadvantages of different enhancing methods and technologies of flotation separation were also deeply explored. To overcome the impact of the small mass of fine coal slime, flocculation flotation is a common technique to increase the apparent particle size of particles. Its flotation enhancement performance is significant, while the selectivity and cost of reagents need to be considered. Both carrier flotation and ultrasonic standing-wave agglomeration have good potential, but they are currently in the laboratory research stage. Reducing the bubble size is an effective means to improve the collision probability between particles and bubbles. The nanobubble flotation technology can significantly improve the recovery rate of fine coal slime and effectively reduce the dosage of reagents. The probability of collision and adhesion between particles and bubbles can also be improved by strengthening the flow field regulation. Turbulence enhancement can effectively promote the improvement of flotation index. The optimization of collectors is aimed at reducing the cost of reagents and improving the selectivity of reagents. The main research points include improving the dispersibility of traditional reagents, introducing polar groups, and designing new types of reagents. The technologies of reagent emulsification, collector substitutes, compound collectors, and new nanoparticle collectors have all shown good strengthening effects in varying degrees. However, their preparation costs and possible environmental impacts are urgent problems that need to be addressed. In addition, for the challenge of fine coal slime separation, the core breakthrough point of flotation equipment optimization is the efficient mineralization of target minerals and the effective suppression of gangue minerals. Multiple flotation and classification flotation are the important technological innovations to solve the problem of incomplete separation of fine coal slime. Pretreatment intensification technologies such as slurry classified conditioning, ultrasonic and high shear effectively improve the uniformity of reagents and slurry, as well as the collision probability between reagents and coal particles, thereby enhancing the flotation separation performance. Among the different enhancing methods and technologies of flotation separation mentioned above, flocculation flotation, ultrasonic standing-wave agglomeration, nanobubble flotation, turbulence intensity regulation, and collector molecular design optimization are all in the laboratory research stage. A large amount of basic theoretical research and semi-industrial research are needed to develop towards industrial application. At present, it is more appropriate and feasible for coal preparation plants to enhance the flotation separation performance of fine coal slime by seeking new cost-effective reagents, upgrading flotation equipment, innovating flotation process, and finely strengthening flotation slurry pretreatment.

    2024 08 v.30;No.168 [Abstract][OnlineView][Download 4071K]



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