In this study,the impact of different reaction times on the preparation of powdered activated carbon(PAC)using a one-step rapid activation method under flue gas atmosphere is investigated,and the underlying reaction m...In this study,the impact of different reaction times on the preparation of powdered activated carbon(PAC)using a one-step rapid activation method under flue gas atmosphere is investigated,and the underlying reaction mechanism is summarized.Results indicate that the reaction process of this method can be divided into three stages:stage I is the rapid release of volatiles and the rapid consumption of O_(2),primarily occurring within a reaction time range of 0-0.5 s;stage II is mainly the continuous release and diffusion of volatiles,which is the carbonization and activation coupling reaction stage,and the carbonization process is the main in this stage.This stage mainly occurs at the reaction time range of 0.5 -2.0 s when SL-coal is used as material,and that is 0.5-3.0 s when JJ-coal is used as material;stage III is mainly the activation stage,during which activated components diffuse to both the surface and interior of particles.This stage mainly involves the reaction stage of CO_(2)and H2O(g)activation,and it mainly occurs at the reaction time range of 2.0-4.0 s when SL-coal is used as material,and that is 3.0-4.0 s when JJ-coal is used as material.Besides,the main function of the first two stages is to provide more diffusion channels and contact surfaces/activation sites for the diffusion and activation of the activated components in the third stage.Mastering the reaction mechanism would serve as a crucial reference and foundation for designing the structure,size of the reactor,and optimal positioning of the activator nozzle in PAC preparation.展开更多
针对火电机组SO_(2)排放质量浓度的影响因素众多,难以准确预测的问题,提出一种改进向量加权平均(weighted mean of vectors,INFO)算法与双向长短期记忆(bi-directional long short term memory,Bi-LSTM)神经网络相结合的预测模型(改进IN...针对火电机组SO_(2)排放质量浓度的影响因素众多,难以准确预测的问题,提出一种改进向量加权平均(weighted mean of vectors,INFO)算法与双向长短期记忆(bi-directional long short term memory,Bi-LSTM)神经网络相结合的预测模型(改进INFO-Bi-LSTM模型)。采用Circle混沌映射和反向学习产生高质量初始化种群,引入自适应t分布提升INFO算法跳出局部最优解和全局搜索的能力。选取改进INFO-Bi-LSTM模型和多种预测模型对炉内外联合脱硫过程中4种典型工况下的SO_(2)排放质量浓度进行预测,将预测结果进行验证对比。结果表明:改进INFO算法的寻优能力得到提升,并且改进INFO-Bi-LSTM模型精度更高,更加适用于SO_(2)排放质量浓度的预测,可为变工况下的脱硫控制提供控制理论支撑。展开更多
Preparation of ceramsite from solid waste based on the sintering process is a new technology and had a high efficiency in improving producing capability, decreasing consumption of liquefied petroleum gas (LPG), and re...Preparation of ceramsite from solid waste based on the sintering process is a new technology and had a high efficiency in improving producing capability, decreasing consumption of liquefied petroleum gas (LPG), and recovering waste heat of flue gas. An experiment sintering gangue ceramsite was conducted in a 25 kg scale sintering pot with a 100 cm height. The combustion characteristics, phase transformation, and the release profile of SO_(2)^(*) (SO and/or SO_(2)) and NO_(x)^(*) (N_(2)O, NO, and/or NO_(2)) of gangue ceramsite during the sintering process were studied by X-ray diffraction analysis, X-ray fluorescence spectrometry, thermogravimetry–differential thermogravimetry–differential scanning calorimetry, and measurement of physical properties of ceramsite and gas components of flue gas. The results showed that the gangue ceramsite had excellent properties, and its compressive strength and water absorption were 8.2–9.6 MPa and 8.9%–9.8%, respectively, far exceeding the requirement of standard (GB/T 17431.1–2010). The ignition temperature of gangue ceramsite was 443 ℃, and the ignition loss was 14.60 mass% at 1000 ℃. Kaolinite and calcite disappeared at 600 and 800 ℃, respectively. Albite disappeared and mullite formed at 1000 ℃. Two peaks of SO_(2)^(*) emissions emerged in the range of 311–346 mg m^(-3) near 500 ℃ of upper layer ceramsite and 420–489 mg m^(-3) near 1000 ℃ of lower layer ceramsite, respectively. NO_(x)^(*) emissions peak emerged in the range of 227–258 mg m^(-3) near 550 ℃ of the upper layer ceramsite, which was related to the oxidation of sulfide and the combustion of LPG. Gangue is a direct heat source for sintering of ceramsite as well. During sintering process, the heat of flue gas above and below 400 ℃ accounts for 55.9% and 30.0% of the all-output heat, respectively, and was potentially used for producing waste-heat steam or electricity as by-products and drying raw materials during its own initial sintering process, which can realize combined mass and heat utilization for the gangue and further reduce the cost of sintered gangue ceramsite.展开更多
H_(2)S selective catalytic oxidation technology is a prospective way for the treatment of low concentration acid gas with simple process operation and low investment. However, undesirable results such as large formati...H_(2)S selective catalytic oxidation technology is a prospective way for the treatment of low concentration acid gas with simple process operation and low investment. However, undesirable results such as large formation of SO_(2) and catalyst deactivation inevitably occur, due to the temperature rise of fixed reaction bed caused by the exothermic reaction. Catalyst with high activity in wide operating temperature window, especially in high temperature range, is urgently needed. In this paper, a series of copper-substituted hexaaluminate catalysts (LaCu_(x), x = 0, 0.5, 1, 1.5, 2, 2.5) were prepared and investigated for the H_(2)S selective oxidation reaction at high temperature conditions (300-550℃). The LaCu_(1) catalyst exhibited excellent catalytic performance and great stability, which was attributed to the best reductive properties and proper pore structure. Besides, two facile deep processing paths were proposed to eliminate the remaining H_(2)S and SO_(2) in the tail gas.展开更多
With the rapid development of electricity production, SO 2 from coal fired power stations causes severe air pollution problem. In 1997, the SO 2 emitted from thermal power plants reached 7.0 Mt, accounting for abou...With the rapid development of electricity production, SO 2 from coal fired power stations causes severe air pollution problem. In 1997, the SO 2 emitted from thermal power plants reached 7.0 Mt, accounting for about 33% of the national emissions. At present and in the future, thermal power stations will still be the primary pollution sources. The Chinese government and power departments accord considerable importance to the SO 2 emissions from thermal power plants. New sets of environmentally friendly policies have been formulated. But, enforcement of laws and regulations needs to be further improved and broadened, especially those responding to market conditions. This paper focuses particular attention on the analysis of strategy, policies, and measures that have been or should be taken against SO 2 emissions from thermal power plants so as to achieve the environmental protection targets, on the basis of which the technical options for the future are given.展开更多
基金supported by the Qingdao Postdoctoral Program Funding(QDBSH20220202045)Shandong provincial Natural Science Foundation(ZR2021ME049,ZR2022ME176)+1 种基金National Natural Science Foundation of China(22078176)Taishan Industrial Experts Program(TSCX202306135).
文摘In this study,the impact of different reaction times on the preparation of powdered activated carbon(PAC)using a one-step rapid activation method under flue gas atmosphere is investigated,and the underlying reaction mechanism is summarized.Results indicate that the reaction process of this method can be divided into three stages:stage I is the rapid release of volatiles and the rapid consumption of O_(2),primarily occurring within a reaction time range of 0-0.5 s;stage II is mainly the continuous release and diffusion of volatiles,which is the carbonization and activation coupling reaction stage,and the carbonization process is the main in this stage.This stage mainly occurs at the reaction time range of 0.5 -2.0 s when SL-coal is used as material,and that is 0.5-3.0 s when JJ-coal is used as material;stage III is mainly the activation stage,during which activated components diffuse to both the surface and interior of particles.This stage mainly involves the reaction stage of CO_(2)and H2O(g)activation,and it mainly occurs at the reaction time range of 2.0-4.0 s when SL-coal is used as material,and that is 3.0-4.0 s when JJ-coal is used as material.Besides,the main function of the first two stages is to provide more diffusion channels and contact surfaces/activation sites for the diffusion and activation of the activated components in the third stage.Mastering the reaction mechanism would serve as a crucial reference and foundation for designing the structure,size of the reactor,and optimal positioning of the activator nozzle in PAC preparation.
文摘针对火电机组SO_(2)排放质量浓度的影响因素众多,难以准确预测的问题,提出一种改进向量加权平均(weighted mean of vectors,INFO)算法与双向长短期记忆(bi-directional long short term memory,Bi-LSTM)神经网络相结合的预测模型(改进INFO-Bi-LSTM模型)。采用Circle混沌映射和反向学习产生高质量初始化种群,引入自适应t分布提升INFO算法跳出局部最优解和全局搜索的能力。选取改进INFO-Bi-LSTM模型和多种预测模型对炉内外联合脱硫过程中4种典型工况下的SO_(2)排放质量浓度进行预测,将预测结果进行验证对比。结果表明:改进INFO算法的寻优能力得到提升,并且改进INFO-Bi-LSTM模型精度更高,更加适用于SO_(2)排放质量浓度的预测,可为变工况下的脱硫控制提供控制理论支撑。
基金support of the Shendong Buertai Colliery and Shandong ECON Energy Saving Technology Co.,Ltd on experimentssupport from the National Key R&D Program Project(Grant No.2019YFC1905705)is greatly acknowledged.
文摘Preparation of ceramsite from solid waste based on the sintering process is a new technology and had a high efficiency in improving producing capability, decreasing consumption of liquefied petroleum gas (LPG), and recovering waste heat of flue gas. An experiment sintering gangue ceramsite was conducted in a 25 kg scale sintering pot with a 100 cm height. The combustion characteristics, phase transformation, and the release profile of SO_(2)^(*) (SO and/or SO_(2)) and NO_(x)^(*) (N_(2)O, NO, and/or NO_(2)) of gangue ceramsite during the sintering process were studied by X-ray diffraction analysis, X-ray fluorescence spectrometry, thermogravimetry–differential thermogravimetry–differential scanning calorimetry, and measurement of physical properties of ceramsite and gas components of flue gas. The results showed that the gangue ceramsite had excellent properties, and its compressive strength and water absorption were 8.2–9.6 MPa and 8.9%–9.8%, respectively, far exceeding the requirement of standard (GB/T 17431.1–2010). The ignition temperature of gangue ceramsite was 443 ℃, and the ignition loss was 14.60 mass% at 1000 ℃. Kaolinite and calcite disappeared at 600 and 800 ℃, respectively. Albite disappeared and mullite formed at 1000 ℃. Two peaks of SO_(2)^(*) emissions emerged in the range of 311–346 mg m^(-3) near 500 ℃ of upper layer ceramsite and 420–489 mg m^(-3) near 1000 ℃ of lower layer ceramsite, respectively. NO_(x)^(*) emissions peak emerged in the range of 227–258 mg m^(-3) near 550 ℃ of the upper layer ceramsite, which was related to the oxidation of sulfide and the combustion of LPG. Gangue is a direct heat source for sintering of ceramsite as well. During sintering process, the heat of flue gas above and below 400 ℃ accounts for 55.9% and 30.0% of the all-output heat, respectively, and was potentially used for producing waste-heat steam or electricity as by-products and drying raw materials during its own initial sintering process, which can realize combined mass and heat utilization for the gangue and further reduce the cost of sintered gangue ceramsite.
基金financially supported by the National Natural Science Foundation of China (Nos. 21976176, 22006148)the Key R&D Program of Shandong province (No. 2019JZZY010506)the Fundamental Research Funds for the Central Universities。
文摘H_(2)S selective catalytic oxidation technology is a prospective way for the treatment of low concentration acid gas with simple process operation and low investment. However, undesirable results such as large formation of SO_(2) and catalyst deactivation inevitably occur, due to the temperature rise of fixed reaction bed caused by the exothermic reaction. Catalyst with high activity in wide operating temperature window, especially in high temperature range, is urgently needed. In this paper, a series of copper-substituted hexaaluminate catalysts (LaCu_(x), x = 0, 0.5, 1, 1.5, 2, 2.5) were prepared and investigated for the H_(2)S selective oxidation reaction at high temperature conditions (300-550℃). The LaCu_(1) catalyst exhibited excellent catalytic performance and great stability, which was attributed to the best reductive properties and proper pore structure. Besides, two facile deep processing paths were proposed to eliminate the remaining H_(2)S and SO_(2) in the tail gas.
文摘With the rapid development of electricity production, SO 2 from coal fired power stations causes severe air pollution problem. In 1997, the SO 2 emitted from thermal power plants reached 7.0 Mt, accounting for about 33% of the national emissions. At present and in the future, thermal power stations will still be the primary pollution sources. The Chinese government and power departments accord considerable importance to the SO 2 emissions from thermal power plants. New sets of environmentally friendly policies have been formulated. But, enforcement of laws and regulations needs to be further improved and broadened, especially those responding to market conditions. This paper focuses particular attention on the analysis of strategy, policies, and measures that have been or should be taken against SO 2 emissions from thermal power plants so as to achieve the environmental protection targets, on the basis of which the technical options for the future are given.
