发电及环境保护
- The Paper
A Two-Stage Acoustic Tomography Method for Temperature Distribution Reconstruction
Abstract：ObjectivesTo improve the reconstruction accuracy of temperature distribution in acoustic tomography, a two-stage reconstruction algorithm based on compressed sensing and multi-scale dilated convolution is proposed.MethodsFirst, a compressed sensing model for reconstructing temperature distribution in acoustic tomography is developed, and the orthogonal matching pursuit (OMP) algorithm is used to obtain a coarse-grid temperature distribution. Then, a multi-scale convolutional neural network is established to predict the fine-grid temperature distribution reconstruction results, where a compensation channel for original measurement is incorporated to enhance the utilization of prior information. Three numerical models of typical temperature distributions are established and compared with the OMP, algebraic reconstruction technique (ART), simultaneous algebraic reconstruction technique (SART), and Landweber algorithms.ResultsThe proposed algorithm achieves an average relative error and a root mean square error of 0.45% and 0.64%, respectively, with reconstruction errors lower than those of other algorithms.ConclusionsThe two-stage temperature distribution reconstruction algorithm can effectively alleviate the ill-posedness of the temperature distribution reconstruction problem, thereby improving the reconstruction accuracy.Keywords：acoustic tomography;high-resolution reconstruction;compressed sensing;multi-scale dilated convolution;orthogonal matching pursuit45|28|0
<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Effects of Variable-Flow Water Distribution on Cooling Performance of Wet Cooling Towers and Its Optimization
Abstract：ObjectivesWhen distributing water across the whole tower under different water flow rates, the water distribution uniformity has a significant effect on the cooling performance of wet cooling tower. In order to realize the high efficiency and energy-saving operation of wet cooling tower in the whole process of deep peak-shaving of wet cooling power units, the influence of the variable flow rate of the wet cooling tower on the water distribution uniformity and cooling performance of the whole tower is studied, and the water distribution optimization is carried out.MethodsBased on the theoretical calculation model for water distribution in wet cooling tower and the three-dimensional thermal calculation model, the variation characteristics of water mass flow rate, water distribution and its non-uniformity during whole-tower water distribution under single-pump and dual-pump operation are studied. The influence of variable flow water distribution on the surface water temperature and average water temperature of cooling tower pool is analyzed, and the optimization scheme of water distribution is put forward.ResultsWhen switching from dual-pump to single-pump operation, the non-uniformity coefficient of water distribution in the inner zone is increased from 3.8% to 6.8% under the scheme only considering the optimization of water distribution in dual-pump operation, and zero spray phenomenon occurs at the end of some water distribution pipes in the outer zone, which weakens the cooling performance of the outer zone when the water distribution of the whole tower is operated by single-pump. Combined with the flow change of circulating water pump under variable operating conditions, an optimization scheme of water distribution in the whole tower integrating single-pump and dual-pump operation is proposed, which can reduce the average outlet water temperature by 0.8 ℃ under the single-pump operation.ConclusionsConsidering the optimization design of the water distribution uniformity of the whole tower during the variable flow water distribution of the wet cooling tower, the high efficiency and energy-saving operation of the cold end of the wet cooling units under the full working condition of the deep peak-shaving can be realized.Keywords：thermal power generation;cooling tower;variable flow rate water distribution;water distribution uniformity;water distribution optimization;cooling performance;deep peak-shaving;energy-saving56|94|0<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Numerical Analysis of Particle Residence Time Distribution Characteristics in Fluidized Bed Based on Orthogonal Test
Abstract：ObjectivesThe residence time distribution (RTD) of particles is an important index to evaluate gas-solid mixing degree in fluidized bed, but there are many influencing factors and it is difficult to control. In order to design and optimize the fluidized bed with continuous operation, it is necessary to explore the influence of structure and operation parameters on RTD of particles.MethodsBased on the Eulerian-Eulerian two-fluid model coupled with the component transport equation, a three-dimensional numerical calculation model of the particle RTD in a rectangular fluidized bed with continuous operation is established. The orthogonal simulation tests with 25 sets are designed to investigate the effects of the baffle structure, number, flow width, particle inlet mass flow rate, and superficial gas velocity on the particle RTD.ResultsThe inlet mass flow rate of particles has the most significant effect on the average residence time of particles, followed by the superficial gas velocity, and both of them are inversely proportional to the average residence time of particles. However, for the dimensionless variance of RTD, the number of baffles and the mass flow rate are important influencing factors. The increase of them will reduce the dimensionless variance, weaken the backmixing degree of the fluidized bed, and make the flow tend to plug flow, but the number of baffles has a greater impact.ConclusionsThe average residence time of particles can be effectively controlled by adjusting the mass flow rate of particles. The number of baffles is a key structural parameter for designing fluidized beds.The research results can provide theoretical guidance for the design and optimization of fluidized bed.Keywords：fluidized bed;heat transfer;residence time distribution;orthogonal test;optimal design54|30|0<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Analysis of Influence of Coal-Ammonia Co-firing on the Heat Transfer Characteristics of Heating Surfaces in Coal-Fired Boiler
Abstract：ObjectivesAmmonia co-firing is an effective way to reduce carbon emission from coal-fired boiler. However, there are few studies on the analysis of ammonia co-firing from the perspective of the entire furnace scale. Therefore, the heat transfer behavior under different loads are systematically analyzed.MethodsCombined with numerical simulation and boiler thermodynamic calculation, the influence of ammonia co-firing on the heat transfer of furnace and convection heating surface of a 600 MW subcritical coal-fired boiler under different loads of 50%- 100% is investigated. The variation characteristics of working fluid temperature, flue gas temperature and boiler efficiency with varying ammonia co-firing ratios (0-40% calorific value ratio) are analyzed.ResultsThe furnace outlet flue gas temperature tends to decrease with increasing ammonia co-firing ratio. By adjusting the attemperation water of boiler, the outlet temperature of the working fluid on each heating surface remains stable when co-firing 0-40% ammonia. Additionally, the temperature of primary and secondary hot air at the air preheater outlet slightly decreases with a higher proportion of ammonia. Compared with pure coal combustion, the exhaust gas temperature of the boiler increases by 7.8-8.1 ℃at 20%-40% ammonia co-firing ratio, leading to a decrease of boiler efficiency by 0.9%-1.1%.ConclusionsAppropriately adjusting the parameters, stable boiler operation can be maintained with an ammonia co-firing ratio below 50%.The findings provide a theoretical basis and practical guidance for the application of coal-ammonia co-combustion technology.Keywords：coal-fired power generation;coal-fired boiler;ammonia co-firing;numerical simulation;heat transfer characteristic;thermodynamic calculation88|37|2<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Application and Optimization Research on Combined Denitrification Technology in 350 MW Supercritical Circulating Fluidized Bed Boiler
Abstract：ObjectivesSelective catalytic reduction (SCR) denitrification technology is widely used in circulating fluidized bed boilers in thermal power plants. During actual operation, the amount of ammonia used is too high and the ammonia escape rate is high, resulting in air preheater corrosion, blockage, and high differential pressure. In order to solve these problems, the denitration system of a 350 MW supercritical circulating fluidized bed boiler in a power plant was reformed and optimized.MethodsA layer of SCR catalyst was added between the secondary economizer and the primary economizer of the supercritical circulating fluidized bed boiler, and a urea lance was added at the flue gas outlet of the cyclone separator. The low-NOx combustion was achieved by grading the air supply and optimizing the air volume. The ammonia injection system was controlled in separate areas to achieve precise ammonia injection, and the equipment was regularly maintained.ResultsAfter modification and optimization, on the basis of achieving ultra-low emissions, the input temperature of the ammonia injection system is reduced, the boiler can run continuously and stably under 30% load. Moreover, the use of urea is reduced, the ammonia escape rate is decreased, and there is basically no ash deposit on the heat storage element of air preheater and the bag of electrostatic precipitator. The pressure difference between them is less than the design value.ConclusionsThe operation efficiency of the denitration system can be improved effectively and the ammonia escape rate can be reduced by reforming and optimizing the denitration system.Keywords：thermal power;coal combustion;circulating fluidized bed boiler;denitration;ultra-low emission;selective catalytic reduction (SCR);ammonia escape rate;NOx emission77|86|0<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Experimental Study on Wide-Load Low-NOx Combustion Retrofit for Circulating Fluidized Bed Boiler Burning High-Alkali Coal
Abstract：ObjectivesDuring the operation of a 440 t/h circulating fluidized bed (CFB) boiler burning high-alkali coal in Xinjiang, China, it is found that its NOx emissions do not meet the standard. Consequently, an experimental study for low-NOx combustion retrofit is conducted on this boiler.MethodsNOx emissions are reduced through boiler component modifications and operational parameter adjustments. To enhance separator efficiency and thereby lower the average bed temperature of the boiler, the heating surface of the water-cooled wall is appropriately extended, and the inlet velocity of the separator is increased. The secondary air is optimized by adjusting the height of the secondary air nozzles. To create a reducing atmosphere, a flue gas recirculation system is added.ResultsThrough comprehensive transformation measures, the average bed temperature and furnace flue gas temperature of the boiler are significantly reduced, and the O2 content in the flue gas is effectively decreased. A more uniform temperature field and a reducing atmosphere are created, both of which are conducive to suppressing NOx formation, thereby reducing NOx generation and emissions.ConclusionsFollowing the retrofit, ultra-low NOx emissions (below 40 mg/m3) are achieved under wide-load conditions even without employing selective non-catalytic reduction (SNCR). This retrofit practice holds positive implications and reference value for low-NOx combustion control in existing CFB boilers.Keywords：pure burning of high-alkali coal;circulating fluidized bed (CFB) boiler;boiler retrofit;low-NOx combustion;ultra-low emissions;wide load;reducing atmosphere120|27|0<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Prediction of NOx Concentration at Inlet Section of SCR Denitrification Reactor Based on Bidirectional Long Short-Term Memory Network and Least Squares Support Vector Machine Model
Abstract：ObjectivesTo address the delayed dynamic adaptation between the ammonia injection command and the NOx concentration at the inlet section of the selective catalytic reduction (SCR) denitrification reactor, as well as the insufficient ammonia injection accuracy in current SCR denitrification ammonia injection control systems, a prediction model for the NOx concentration at the inlet section of the SCR denitrification reactor of a 660 MW coal-fired unit is developed.MethodsThe sampled data from the coal-fired unit are preprocessed in combination with the flue duct structure of the unit. Subsequently, a bidirectional long short-term memory network (BiLSTM) is applied to generate a preliminary prediction of the NOx concentration at the inlet section of the SCR denitrification ammonia injection reactor. Next, a least squares support vector machine (LSSVM) is utilized to correct the prediction residuals, thereby minimizing the prediction error of the model to the greatest extent. Finally, in order to evaluate the prediction performance of the proposed model, simulation and real-time validation are carried out.ResultsThis model exhibits excellent performance in predicting the NOx concentration at the inlet section of the SCR reactor under various unit load conditions and variable coal quality conditions. The prediction error in real-time validation is only 5.772 mg/m3, with an advance prediction capability of 8.5 s.ConclusionsThis prediction model can provide accurate feedforward information for the ammonia injection control system.Keywords：coal-fired unit;data preprocessing;neural network prediction;denitrification;bidirectional long short-term memory network (BiLSTM);least squares support vector machine (LSSVM);selective catalytic reduction (SCR) reactor;NOx concentration prediction99|42|0<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Analysis of Influence of Flue Gas Recirculation on Thermodynamic Performance and Economic Efficiency of 125 MW Supercritical CO2 Coal-Fired Power Generation Unit
Abstract：ObjectivesFlue gas recirculation (FGR) can effectively mitigate the issue of high furnace wall temperature in supercritical carbon dioxide (S-CO2) boilers. The selection of an appropriate flue gas recirculation rate is critical for the design of S-CO2 boilers. Therefore, this study analyzes the influence of different flue gas recirculation rates on the thermodynamic performance and economic efficiency of the boilers.MethodsA 125 MW S-CO2 coal-fired boiler is taken as the research object. The thermodynamic performance of the boiler under different flue gas recirculation rates is analyzed using a thermodynamic calculation method and the conceptual design is proposed, while keeping the boiler efficiency constant. On this basis, the economic efficiency of the boiler and the unit is further studied using the multistage weighted mass method and levelized cost of electricity.ResultsWith increasing flue gas recirculation rate, the material cost of boiler’s radiant heating surface decreases, while the cost of other heating surfaces increases, leading to an increase in the total investment cost of the boiler. However, FGR results in additional costs for fans, fuel, and other extra expenses.ConclusionsConsidering both safety and economic efficiency, a flue gas recirculation rate of 20%-30% is recommended for optimal boiler design.Keywords：thermal power generation;coal-fired power generation;supercritical carbon dioxide (S-CO2);boiler;economic analysis;flue gas recirculation (FGR);thermal calculation80|11|1<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Integrated Modeling Study of Desulfurization in Circulating Fluidized Bed Boilers Under Wide Load Conditions
Abstract：ObjectivesWith the proposal of the “carbon peaking and carbon neutrality” goal, the proportion of clean energy generation in China continues to increase. In order to promote the consumption of new energy generation, thermal power units frequently adopt the wide load peak shaving operation mode. Therefore, it is necessary to establish a SO2 emission concentration model for coal-fired circulating fluidized bed (CFB) boilers that can adapt to wide load operation conditions to achieve ultra-low SO2 emission of CFB units.MethodsThrough in-depth research on the dynamic characteristics of SO2 generation and removal, a dynamic lumped parameter model of SO2 emission concentration at the furnace outlet is established using mechanism analysis method combined with mass conservation equation. A comprehensive dynamic model for the entire desulfurization process from coal supply and air supply to SO2 emission at the outlet of the desulfurization tower is established by reasonably simplifying the input of the model. The simulation verification is carried out by using the steady-state and dynamic operating condition data segments from the actual measurement data of CFB boilers.ResultsThe established dynamic model can predict the dynamic trend of net flue gas emissions approximately 240 seconds in advance.ConclusionsThe model can reflect the dynamic characteristics of the desulfurization process in the furnace, and has certain applicability under wide load conditions.Keywords：coal-fired power generation;thermal power unit;circulating fluidized bed (CFB);SO2 emission characteristics;dynamic modeling;wide load integration;pollutant emission171|669|0<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29Multi-Objective Optimization Analysis of Gas-Steam Combined Cycle Power Generation Systems
Abstract：ObjectivesTo improve the efficiency of gas-steam combined cycle power generation units, an optimized design of thermodynamic systems is required. Therefore, a multi-objective optimization modeling method for combined cycle power generation systems, simultaneously considering thermal efficiency, operating cost, and carbon emission is proposed.MethodsThe gas cycle is modeled incorporating blade cooling, while the steam cycle is modeled based on a triple-pressure reheat heat recovery steam generator. The constructed mixed-integer nonlinear mathematical programming model is solved using GAMS software to optimize the generation units, explore optimal design parameters of the combined cycle power generation system including cycle pressure ratio, turbine inlet temperature, and bottom-cycle steam parameters, and analyze trade-off relationships among multiple objectives.ResultsTurbine inlet temperature has the most significant effect on cycle efficiency, total cost, and carbon emissions. When conducting multi-objective optimization that balances combined cycle efficiency, total system cost, and carbon emissions, the combined cycle efficiency should be 65%.ConclusionsThe proposed method can more effectively optimize the thermodynamic parameters of large-scale generation units to achieve energy saving, emission reduction, and improved energy efficiency.Keywords：combined cycle generator sets;multi-objective optimization;carbon emission;thermodynamic calculation;waste heat boiler;cycle pressure ratio;simulated analysis189|599|1<HTML><L-PDF><WORD><Meta-XML>Updated：2026-06-29
