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- Abstract：The transformation mechanism of minerals in coal ash under different atmospheric conditions affects the melting and slagging process of coal. In order to study the melting characteristics of Zhundong coal under oxygen-rich/H2O-O2 atmosphere, and provide reference for preventing the slagging of Zhundong coal-fired boilers, the charge coupled device (CCD) camera was used to record the deformation process of the pulverized Zhundong coal on the hot stage. By calculating the sampling areas of the pulverized coal at different temperatures, the melting temperatures corresponding to the characteristic change points of the pulverized coal areas were obtained. The temperatures at which Zhundong coal powder began to melt under different oxygen-rich/H2O-O2 atmosphere conditions were compared. The study have shown that as the oxygen concentration increases, the temperature at which the coal powder begins to melt decreases. As the water vapor concentration decreases, the temperature at which the coal powder begins to melt increases. Both water vapor atmosphere and oxygen-rich atmosphere can promote the melting behavior of Zhundong coal.Keywords：Zhundong coal;melting characteristics;oxygen-rich atmosphere;H2O-O2 atmosphere;hot stage experiment;charge coupled device (CCD) camera70|90|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：A 3D coupled mathematical model of 1 000 MW ultra-supercritical tower boiler was established. Based on the design parameters of the boiler, the model calculated the flow and heat transfer process of the boiler in operation. The model was used to simulate different load conditions of the supercritical boiler. The boiler maximum continuous rating (BMCR) condition, 75% BMCR condition and 50% BMCR condition were selected to explore the heat transfer during peak shaving operation. By analyzing the temperature and heat flux distribution in the furnace and the temperature distribution in the tube and on the water cooled wall, it is found that the temperature and heat flux change of the BMCR, 75% BMCR are in the similar trend while the temperature change of the 50% BMCR is irregular, and the heat transfer deterioration is prone to occur in the spiral water cooled wall region.Keywords：ultra-supercritical boiler;3D coupled simulation;heat transfer;peaking operation84|128|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：A two-dimensional unsteady continuous solid phase model was established for the packed bed phase change thermal storage tank, and its thermal storage performance was numerically studied. The simulation results reveal the change of thermocline and the distribution state of heat transfer temperature difference during thermal storage. The influence of the initial temperatures, inlet temperatures and phase change capsule diameters on the thermal storage performance were investigated, the results were compared with the existing literature for verification. In order to further improve the packing rate, this paper puts forward the packing optimization scheme of particle diameter obeying Alfred distribution in combination with the theory of particle accumulation. According to the calculation results, this optimization method significantly improves thermal storage under the condition of a small increase in thermal storage time, and has a good optimization effect.Keywords：energy storage;phase change thermal storage;porous medium;thermocline;closet packing40|205|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Tesla disc turbine is a kind of unconventional turbine utilizing viscous force in the boundary layer to drive the rotor. Due to the simple structure and low cost as well as the good adaptability to the working fluids, Tesla disc turbine is especially adaptable to the low-grade heat source recovery system. But the unique working principle results in the low operation torque and low efficiency comparing with the common forms of turbines, thus the commercial application of disc turbine is limited. The blades were added between adjacent discs and a mathematcial model for the new turbine structure was formulated. Computational fluid dynamics (CFD) verified that the present mathematical model could calculate the velocity and pressure distribution of the working fluid in the flow field and could predict the efficiency variation trend under different working conditions. Utilizing the present mathematical model, calculations and comparisons were made aiming at low-grade heat recovery organic rankine cycle (ORC) system using different working fluids. The results show that, with different working fluids, adding blades between discs in Tesla disc turbine could significantly improve the operation torque and turbine efficiency.Keywords：power generation;waste heat recovery;disc turbine;mathematical model;computational fluid dynamics (CFD);organic rankine cycle (ORC)46|201|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：When the flue gas passes through the wet desulfurization of the coal-fired unit, its temperature drops and becomes saturated when it is discharged into the environment through the chimney, and then the condensation is formed, called as "white smoke" phenomenon. The theoretical calculation model of exhaust gas temperature for each white smoke elimination technology of coal-fired units was established. The characteristics of white smoke elimination technology in different regions were calculated by taking Xi'an, Shijiazhuang and Shanghai as examples. Results show that the flue gas directly heating method can effectively eliminate white smoke when the ambient temperature is high. When the ambient temperature is low, the flue gas cooling and reheating method would be more effectively. In spring and summer, the white smoke can be eliminated by directly heating method, and the exhaust flue gas temperature should be controlled between 60℃ and 75℃ according to environmental factors. In autumn and winter, when the ambient temperature is 9℃ and the relative humidity is 60% or less, the white smoke should be removed by the cooling and reheating method. In autumn, the flue gas temperature should be lowered to 45℃ and then heated to 75℃. In winter, it can be lowered to 45℃ and then heated to 85℃.Keywords：wet desulfurization;white smoke elimination;directly heating;cooling and reheating54|351|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The design of the SCR denitrification system in coal-fired power plants requires the efficient denitrifi-cation efficiency and the low cost. Hence, it is essential to accurately calculate the volume of SCR denitrification catalysts. The flue gas conditions of thermal power plants are complex and changeable. Flue gas temperature, flue gas flow, inlet and outlet NOx concentrations, and other parameters all affect the volume of the SCR catalyst.Therefore, catalyst volume prediction is a multifactor coupling problem. For this feature, the BP neural network model was used to predict the volume design of the catalyst, and the neural network modeling based on genetic algorithm optimization was investigated for the structural defects of the BP neural network model. The results show that the prediction accuracy of BP neural network model optimized by genetic algorithm is promising, which provides a new way for catalyst volume design of SCR denitrification.Keywords：SCR catalyst;catalyst volume prediction;BP neural network;genetic algorithm47|192|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The integration of heat pump can realize heat-power decoupling, and would influence the energy consumption characteristics of combined heat and power cogeneration plants (CHP). Therefore, a 350MW CHP unit was taken as a reference case, and the off-design calculation models of CHP unit and the heating calculation models of heat pump were established. The minimum power load rate and the coal consumption rate of the CHP plants with steam extraction and heat pump to supply heat were compared. The influences of the heat pump performance coefficient, the power load rate and the heat load rate on energy consumption characteristics of CHP plants were also studied. Results show that the compression heat pump can save energy on benchmark condition and its power load regulation range is also greater. The coal saving rate increases with the increase of αCOP1 and heat load rate, and decreases as power load rate increases. When the αCOP1 is 6.119, the heat load rate is 2.5, and the electric load rate is 0.8, the coal saving rate is 2.60%.Keywords：heat and power cogeneration;heat pump;heat-power decoupling;power load rate;heat load rate58|283|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：In order to study the aggregation mechanism and particulate emission reduction characteristics of the flue agglomerator, the flow field characteristics of the turbulent region of the agglomerator under steady/unsteady conditions were simulated and obtained by commercial computational fluid dynamics (CFD) software.The agglomeration process of particles in the agglomerator was theoretically calculated and verified by scanning electron microscope (SEM). The agglomerator in the laboratory reduced PM2.5 emissions by 20.8%, compared with 30.1% and 37% in the actual project. The results can provide reference for large-scale engineering application of particle coagulation technology.Keywords：coal-fired power plant;agglomerator;fine particulate matter;turbulence36|150|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：In order to enhance the deep peak-regulating capacity of ultra-supercritical thermal power units and solve the problem of large capacity units with low efficiency at low load section, the 1 000 MW unit with high efficiency and wide regulation load demonstration project was put forward and constructed. The burner and water wall of the boiler and steam turbine parameters were applied to the optimization design. The model and operation mode of water supply pumps, condensate pumps, circulating pumps and other auxiliary equipment were optimized. By adding a supplementary steam valve, an external cooler, No.0 high pressure heater, low temperature economizer and other equipment, the unit still maintain a relatively high efficiency in a wide range of target load. The thermal calculation results show that the efficiency of the demonstration unit is 3% higher than the existing unit at 50% load, and the operation flexibility of the demonstration unit has been significantly enhanced, which has made obvious economic and social benefits. The related experience has a reference value for the subsequent similar units to enhance their flexibility.Keywords：high efficiency;wide regulation load;unit peak-regulating;flexibility;optimization integration73|384|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The economy of the power plant could be effectively improved by the deep utilization of waste heat. Several types of waste heat utilization methods at home and abroad were reviewed, including the conventional waste heat utilization method and several new methods, such as heat ex-changer grading, bypass flue technology and heat pump technology. A detailed comparison of the energy-saving effects of different waste heat utilization methods was conducted. It is considered that the heat recovered from conventional low-temperature economizer flue gas is relatively limited. The graded waste heat utilization can be achieved by the hierarchical method. The bypass flue technology is more economical because of the displaces of extraction from higher-grade steam turbines. The energy quality can be further enhanced by the heat pump technology.Keywords：power plant;waste heat utilization;bypass flue;heat pump58|706|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The exhaust heat loss of supercritical power station boilers is very large. Recovery and utilization of waste heat from boiler can effectively improve the thermal economy of power plants, and reduce coal consumption and environmental pollution. At present, the way most widely used to improve the utilization efficiency of flue gas waste heat in thermal power plants is to install low temperature economizer. The waste heat utilization technology of a supercritical unit boiler was studied, different low-temperature economizer layout schemes were analyzed, and a technical scheme for recovery of waste heat from power plant boiler by using dual-stage low-temperature economizer was proposed, i.e., the combination of low-temperature flue gas and low-condensation water heat exchange technology, the energy of front air pre-heater and low-temperature economizer. The source cascade utilization mode can achieve optimal energy saving and optimal investment return.Keywords：supercritical unit;flue gas waste heat;boiler;low temperature economizer;prepositioned air pre-heater46|369|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：A circulating fluidized bed (CFB) boiler of the 330 MW unit have problems such as nonuniform bed temperature, heating surface wear, tube burst and so on. Combustion optimizing adjustment test was carried out to solve these problems. Adjustment test result show that through key operation parameters such as optimizing primary air flow, total air flow and wind-box pressure, the best operation condition and parameters are determined, average carbon content in bottom ash and fly ash is reduced, boiler thermal efficiency is increased by 0.85%. Total power of primary air fan and secondary air fan is reduced by 0.8MW, auxiliary power rate also is decreased by 0.24%. Operational safety and economy of the boiler has been further improved.Keywords：circulating fluidized bed boiler;combustion adjustment;average carbon content in bottom ash and fly ash;boiler thermal efficiency81|121|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
Energy Clean and Efficient Utilization in Coal-fired Power Systems
- Abstract：For the LCL type filter, there is a natural resonance peak, and the change of the grid impedance in the actual power grid will further affect the stability of the rectifier. The Euler-Lagrangian mathematical model of LCL-type Vienna rectifier in dq synchronous rotating coordinate system was established, and the nonlinear hybrid passive control strategy of LCL-type Vienna rectifier under weak grid conditions was proposed, which theoretically guarantees the progressive of closed-loop system. It is stable and can meet the requirements of the dynamic and static characteristics of the rectifier and the harmonic suppression capability of the AC side under ideal grid and weak grid conditions. At the same time, it can eliminate the coupling term between dq axes in the established system model. In the Matlab/Simulink simulation environment, the feasibility of the proposed control strategy is verified by simulation experiments under ideal grid conditions and weak grid conditions.Keywords：Vienna rectifier;weak grid;LCL filter;decoupling;passivity-based control;robustness47|349|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：With the development of power electronics technology, AC frequency conversion speed regulation system gradually replaces the traditional DC speed regulation drive with its strong advantages. It brings convenience and efficiency to people's production and life, but also causes the problem of aggravating harmonic pollution in power system. Therefore, this paper designed an open-loop sinusoidal pulse width modulation (SPWM) controlled AC variable frequency speed regulation system and built a simulation model, which realized the flexible control of the frequency and amplitude of the output voltage of the converter, as well as the motor speed. Furthermore, the harmonic characteristics of the voltage and current on the grid side of the system were analyzed. The simulation results show that the waveform of the voltage is ideal and its distortion is very small, but the current waveform distortion is serious. In addition, with the increase of the inverter output frequency, the distortion degree of voltage waveform is intensified, and the current distortion is reduced.Keywords：frequency speed regulation;inverter;asynchronous motor;harmonic analysis40|230|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：In order to accurately evaluate the health status of relay protection equipment and improve the management level of relay protection equipment, a relay protection status evaluation method based on multi-source information fusion technology was proposed, in which the technical characteristics of relay protection was fully considered. The evaluation system and index of relay protection were established. The key technical problems of the multi-source information fusion technology used in the state evaluation of relay protection, the function and structure model of state evaluation of relay protection and its application in the life cycle equipment management were solved. The state evaluation method of relay protection was established. Combining with the current situation of life cycle management of relay protection equipment, a solution to the application of relay protection status evaluation results in the process of equipment life cycle management was put forward. A relay protection status maintenance system based on multi-source information fusion technology was developed, being applied to many dispatching units. The correctness and practicability of this method was verifiesd.Keywords：multi-source information fusion;relay protection;state evaluation;life cycle management;condition maintenance decision system57|185|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
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