| Title | Keywords | ||
|---|---|---|---|
| Author | Authorship | ||
| Corresponding Author | Funds | ||
| DOI | Column | ||
| Summary | |||
| Timeframe | - | ||
| Title | Keywords | ||
|---|---|---|---|
| Author | Authorship | ||
| Corresponding Author | Funds | ||
| DOI | Column | ||
| Summary | |||
| Timeframe | - | ||
[Objective] Ammonia selective catalytic reduction(SCR) is considered to be one of the best technologies for controlling the emission of NO_x, the main component of power plant tail gas, in which the catalyst is the core of the technology. The loaded tungsten-cerium catalyst is a non-vanadium based SCR catalyst with excellent denitrification activity in the medium to high temperature range, and it is of great significance to carry out an in-depth study on the regeneration mechanism of its SO_2 poisoning deactivation in order to maintain the long-term and efficient denitrification activity of this catalyst. [Methods] In this study, the SO_2-poisoned WO_3/CeO_2(W/Ce-S) catalyst was heat-treated at 400 ℃ with different atmospheres(N_2, Air-N_2+O_2, NH_3) to investigate the deactivation and regeneration mechanism of SO_2-poisoned WO_3/CeO_2 catalyst. With the help of characterisation tools such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier infrared spectroscopy, thermogravimetric analysis, and hydrogenprogrammed warming reduction, the reasons for the different regeneration effects were explored. [Results] It was found that the denitrification activity of SO_2-poisoned WO_3/CeO_2 catalysts could be restored to different degrees after heat treatment with different atmospheres. Among them, the W/Ce-S activity recovered to 97.4% of the pre-poisoning level after NH_3 heat treatment. With the help of various characterisation means, it was found that this was mainly due to the fact that the ammonium sulphate and metal sulphate species deposited on the surface of the W/Ce-S catalysts were decomposed to the maximum extent after the NH_3 heat treatment, which restored the surface active sites and redox capacity, and promoted the regeneration of its catalytic activity. [Conclusion] The results of the study are conducive to the reduction of denitrification costs in the power industry and provide a theoretical basis for the design of environmentally friendly sulfur-resistant catalysts.
[Objective] The NO_x emissions from solid fuel combustion in coal-fired power plants can cause serious harm to the environment. Therefore, strict control of NO emissions in flue gas is beneficial for reducing the pollution of coalfired power plants to the atmospheric environment, thereby improving air quality. At present, Ammonia Selective Catalytic Reduction(NH_3-SCR) is the most widely used method for achieving flue gas denitrification, and the core of this technology is the design of efficient catalysts. In order to improve the denitrification efficiency of MnO_x catalyst, it is necessary to study the effect of precipitant dosage on its activity. [Methods] In this study, MnO_x catalysts with different amounts of precipitants were prepared using co precipitation method. And through a series of characterization testing methods, a comparative analysis was conducted on catalysts with different amounts of precipitants to explore the mechanism of the influence of precipitant dosage on catalyst activity.[Results] The results showed that the 0.1 AH-MnO_x catalyst prepared with 0.1 mol ammonia water as the precipitant exhibited the best catalytic activity, with a NO conversion rate of over 95% in the range of 200-300 ℃. Through characterization results such as scanning electron microscopy and N_2 adsorption desorption testing, it was found that excessive use of precipitant exacerbated the agglomeration phenomenon of the catalyst, promoted the increase of the catalyst particle structure, and reduced the specific surface area, average pore size, and pore volume of the catalyst. In addition, NH_3-TPD test results showed that as the amount of precipitant increased, the surface acidity of the catalyst also decreased. This is related to the decrease in the specific surface area of the catalyst, which leads to a reduction in the active sites on the catalyst surface, which is not conducive to the adsorption and activation of NH_3, ultimately resulting in a decrease in the reaction activity of the catalyst. The denitrification performance of 0.1 AH MnO_x catalyst is slightly better than that of 0.2 AH MnO_x catalyst. However, due to the low amount of precipitant used in the 0.1 AH-MnO_x catalyst, the catalyst yield is low, resulting in increased production costs. And the morphology, specific surface area, and surface acidity differences between 0.2 AHMnO_x and 0.1 AH-MnO_x catalysts are minimal, while the 0.2 AH-MnO_x catalyst has a higher yield.[Conclusion] Therefore, when preparing catalysts by precipitation method, it is not only necessary to optimize the type of precipitant, but also to pay attention to comprehensive considerations from the aspects of precipitant dosage and cost, in order to achieve the optimal effect.
[Objective] In order to develop an efficient and environmentally friendly low-temperature denitration catalyst and solve the problem that the flue gas temperature cannot meet the optimal reaction temperature of SCR denitration catalyst during low-load operation of coal-fired power plants, the low-temperature activity and anti-poisoning performance of NH_3 selective catalytic reduction(NH_3-SCR) reaction were improved. [Methods] Mo-modified Ce-Zr solid solution(Ce_xZr_(1-x)O_2) catalysts(Mo/Ce_xZr_(1-x)O_2) were designed and prepared via the coprecipitation method and wet impregnation method. Characterization techniques such as XRD, H_2-TPR, and NH_3-TPD were used to analyze the structure, redox capacity, and acid site distribution of the catalysts. [Results] The results show that the formation of a cubic fluorite-structured solid solution by Ce and Zr significantly enhances the redox capacity and specific surface area of the catalyst, while the introduction of MoO_3 provides key acid sites that synergistically promote NH_3 adsorption and activation. Among them, the Mo/Ce_(0.5)Zr_(0.5)O_2(Mo/C5Z5) catalyst exhibits optimal performance: NO conversion > 90% in the temperature range of 200～350 ℃, high N_2 selectivity, and maintains over 80% activity at 250 ℃ under harsh conditions containing 200 μL/L SO_2 and 5% H_2O. Its sulfur and water resistance is significantly superior to traditional vanadium-based catalysts. [Conclusion] This study provides a new strategy for the development of efficient and environmentally friendly low-temperature denitration catalysts, and provides a new idea for solving the problem of mismatch between the optimal activity of denitration catalysts and reaction temperature under low-load operation conditions of coal-fired power plants. In the future, it is necessary to further optimize performance and long-term stability to adapt to complex flue gas environments.
[Objective] With the transformation of the global energy structure and the wide application of renewable energy, photovoltaic power generation system has become one of the important energy sources because of its clean and renewable characteristics. However, the fluctuation of output power from photovoltaic power generation systems poses a challenge to the stability of the power grid. In order to solve the problem of power grid stability caused by the output power fluctuation of photovoltaic power generation system. [Methods] In this paper, an optimization method of optical storage three-phase grid-connected system based on intelligent algorithm optimization and virtual synchronous generator( VSG) technology is proposed. Through in-depth analysis of VSG control principle and the influence of energy storage system control parameters( proportional gain Kp and integral gain Ki) on system voltage, current and frequency, this study constructs the overall model of the three-phase grid-connected system, and uses nondominated sorting genetic algorithm-Ⅱ( NSGA-Ⅱ) to optimize the DC voltage variance and AC frequency variance. The optimization results are comprehensively evaluated by the technique for order preference by similarity to an ideal solution( TOPSIS) method. By comparing with the traditional PI control, the effectiveness of the optimized parameter configuration is verified. [Results] The performance of the VSG control system optimized by TOPSIS in terms of stable frequency and voltage deviation is 50 Hz and-0.064%, respectively, which is significantly better than 50.2 Hz and 0.354% of PI control. The system based on VSG control also performs well in terms of voltage distortion rate and negative sequence voltage imbalance. The voltage sine wave distortion rate is only 0.12%, which is much lower than 3.78% of PI control, and the negative sequence voltage imbalance is 0.002%, which is significantly lower than 0.023% of PI control. The quality of gridconnected voltage is significantly improved, which proves the effectiveness of NSGA-Ⅱ optimized VSG control model in improving system stability and power quality. [Conclusion] This study provides new insights and methodologies for the optimal design of PV energy storage grid-connected systems, offering robust support for the development of renewable energy grid integration technology and facilitating the evolution of future energy management systems towards greater efficiency and reliability.
Under China's national strategic goals of "carbon peak and carbon neutrality," coal-fired power plants, as a crucial pillar of the country's energy system, play a significant role not only in energy security but also directly impact air quality and greenhouse gas emission control. The synergistic control of multiple pollutants during the combustion process, coupled with the transition to low-carbon operations, is emerging as a forefront and critical area of energy technology innovation. Boiler and combustion technologies bear a vital mission in driving green and low-carbon development, with related technological breakthroughs and practical applications poised to directly catalyze the green transformation and upgrading of the energy industry.
[Objective]In order to develop an efficient and environmentally friendly low-temperature denitration catalyst and solve the problem that the flue gas temperature cannot meet the optimal reaction temperature of SCR denitration catalyst during low-load operation of coal-fired power plants, the low-temperature activity and anti-poisoning performance of NH3 selective catalytic reduction (NH3-SCR) reaction were improved. [Methods] Mo-modified Ce-Zr solid solution (Cex Zr1-x O₂) catalysts (Mo/Cex Zr1-x O₂) were designed and prepared via the coprecipitation method and wet impregnation method. Characterization techniques such as XRD, H₂-TPR, and NH₃-TPD were used to analyze the structure, redox capacity, and acid site distribution of the catalysts. [Results] The results show that the formation of a cubic fluorite-structured solid solution by Ce and Zr significantly enhances the redox capacity and specific surface area of the catalyst, while the introduction of MoO₃ provides key acid sites that synergistically promote NH₃ adsorption and activation. Among them, the Mo/Ce0.5 Zr0.5 O₂ (Mo/C5Z5) catalyst exhibits optimal performance: NO conversion > 90% in the temperature range of 200~350 ℃, high N₂ selectivity, and maintains over 80% activity at 250 ℃ under harsh conditions containing 200 μL/L SO₂ and 5% H₂O. Its sulfur and water resistance is significantly superior to traditional vanadium-based catalysts. [Conclusion] This study provides a new strategy for the development of efficient and environmentally friendly low-temperature denitration catalysts, and provides a new idea for solving the problem of mismatch between the optimal activity of denitration catalysts and reaction temperature under low-load operation conditions of coal-fired power plants. In the future, it is necessary to further optimize performance and long-term stability to adapt to complex flue gas environments.
[Objective] With the increasingly stringent "zero discharge" policy for power plant wastewater and emission limits on hydrogen chloride (HCl) from coal-fired flue gas, improving the dechlorination efficiency of coal combustion flue gas has become an urgent issue to address. In order to further reveal the effective method of HCl control, it is the current research focus to compare and analyze various technologies and identify their advantages and disadvantages. [Methods] This paper systematically reviews the literature on three categories of dechlorination pathways—pre-combustion, in-combustion, and post-combustion—comprehensively summarising and comparing the fundamental principles, advantages, and disadvantages of each technology. [Results] Research indicates that coal washing achieves a dechlorination efficiency of approximately 27%-56%, effectively removing inorganic chlorine but with limited effectiveness in eliminating organic chlorine in coal. Furthermore, it is costly and cannot meet the dechlorination needs of coal-fired power plants. In-combustion dechlorination depends on the addition of reactants under high-temperature conditions, but strong competitive reactions with acidic gases such as SO₂ hinder the selective removal of HCl. In contrast, post-combustion dechlorination technologies show greater application potential, especially due to their compatibility with existing flue gas purification systems, enabling efficient and synergistic pollutant control. Among them, wet dechlorination is a mature technology but leads to wastewater discharge issues. Dry/semi-dry methods feature advantages such as no wastewater generation and minimal impact on boiler efficiency. However, these technologies are constrained by factors including flue gas composition effects, incomplete online detection methods, and degradation of fly ash quality. Currently, domestic dry/semi-dry dechlorination efficiencies are mostly below 70%, lower than the 90% efficiency achieved by the U. S. Environmental Protection Agency using Na₂CO₃ ·NaHCO₃ ·2H₂O dry injection. [Conclusion] Overall, post-combustion dry/semi-dry dechlorination technologies hold great potential in meeting environmental regulations, achieving high dechlorination efficiency, and promoting industrial application. They merit further in-depth research and optimization.
[Objective] Ammonia selective catalytic reduction (SCR) is considered to be one of the best technologies for controlling the emission of NOx , the main component of power plant tail gas, in which the catalyst is the core of the technology. The loaded tungsten-cerium catalyst is a non-vanadium based SCR catalyst with excellent denitrification activity in the medium to high temperature range, and it is of great significance to carry out an in-depth study on the regeneration mechanism of its SO2 poisoning deactivation in order to maintain the long-term and efficient denitrification activity of this catalyst. [Methods] In this study, the SO2-poisoned WO3 /CeO2 (W/Ce-S) catalyst was heat-treated at 400 ℃ with different atmospheres (N2 , Air-N2 +O2 , NH3 ) to investigate the deactivation and regeneration mechanism of SO2-poisoned WO3 /CeO2 catalyst. With the help of characterisation tools such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier infrared spectroscopy, thermogravimetric analysis, and hydrogen programmed warming reduction, the reasons for the different regeneration effects were explored. [Results] It was found that the denitrification activity of SO2-poisoned WO3 /CeO2 catalysts could be restored to different degrees after heat treatment with different atmospheres. Among them, the W/Ce-S activity recovered to 97.4% of the pre-poisoning level after NH3 heat treatment. With the help of various characterisation means, it was found that this was mainly due to the fact that the ammonium sulphate and metal sulphate species deposited on the surface of the W/Ce-S catalysts were decomposed to the maximum extent after the NH3 heat treatment, which restored the surface active sites and redox capacity, and promoted the regeneration of its catalytic activity. [Conclusion] The results of the study are conducive to the reduction of denitrification costs in the power industry and provide a theoretical basis for the design of environmentally friendly sulfur-resistant catalysts.