The fault early warning of the coal mill is of great significance to the safe operation of thermal power unit, but the operation of the coal mill has many interference noises and a high degree of coupling, which makes the fault early warning more difficult. Based on this, this paper proposes a fault warning method based on wavelet packet transform (WPT) and Transformer. Firstly, the signal is denoised by the wavelet packet analysis method with adaptive threshold value. Then, the characteristic parameters related to the fault measurement point are selected as input to establish a Transformer coal pulverized prediction model based on the self-attention mechanism. Finally, the kernel density estimation method is used to analyze the prediction deviation and determine the warning threshold. Taking a 660 MW medium-speed coal mill as the research object and using actual data for verification, the experimental results show that the prediction accuracy of the proposed method is higher than that of CNN, LSTM, and CNN+LSTM models, and it can provide early warning of coal mill failures.

The long-term vibration of ZGM133G-I type medium speed coal pulverizers in a power plant causes weld fatigue fracture of the powder delivery pipeline, which results in coal powder leakage, polluting the environment and seriously affecting the operation of the unit. Based on the mechanical vibration analysis and field test of medium-speed coal pulverizers, this paper studies the influence of operating parameters such as loading force, speed of separator and output of coal pulverizers on the vibration of coal pulverizers. The results show that, the vibration of medium-speed coal pulverizers is mainly caused by the mechanical equipment itself and the setting of operating parameters. The size and separator type of coal pulverizers are not the inevitable factors that cause the vibration of coal pulverizers, but the wear and damage of mechanical structure will cause the vibration of coal pulverizers. In order to reduce the vibration of medium-speed coal pulverizers, it is necessary to comprehensively consider the output of coal pulverizers and the fineness of coal powder according to the test results, and reasonably control the loading force, separator speed and output.

It is necessary to break the technical barrier and make breakthroughs in information system, control system, device and other aspects when reforming large thermal power excitation system domestically. The article first systematically concludes and summarizes the key technologies of modern excitation technology, including control and command subsystems, communication subsystems, rectifier subsystems, and excitation subsystems. It analyzes and summarizes the research status, existing problems, and difficulties involved in each technology at home and abroad. Secondly, the localization and replacement process of the HN-i6200 excitation system for large-scale supercritical 670 MW thermal power units was described. Targeted design was carried out to meet the special requirements of the excitation system operation for thermal power units, and highly reliable domestic DC breakers were developed. Through experimental research, the operation strategy of the excitation system for thermal power units was overcome, and a nationally produced HN-i6200 excitation system was successfully developed. The on-site testing and system modeling have verified the working performance of the nationwide production excitation system, providing technical and practical references for the localization of excitation technology in the power industry.

The CO₂ capture process using ionic liquids (ILs) in the coal-fired power plant is simulated, in which the physical properties of ILs and ILs-CO₂ phase equilibria are modelled based on experimental data. Analysis shows that the increase of packed height and absorption pressure is beneficial for CO₂ absorption, while the inlet temperature has the dual effect as it influences both the ILs viscosity and CO₂ solubility. The optimum condition is determined with 20 m packed height, 4 MPa absorption pressure and 50 ℃ inlet temperature. The regeneration process is more energy efficient with pressure swing method, in which the pressure of ILs-CO₂ stream is reduced to 0.1 MPa with almost no ILs loss. Energy consumption and cost analysis shows that the multistage compressor is the most energy-intensive unit, and the absorption pressure has the largest effect on the system with 4 MPa the optimum parameter. With the optimum condition, the energy consumption of the process is 2.21 GJ/t, which is more energy-efficient than the conventional carbon capture system using monoethanolamine.

Creep rupture is one of the most common failure modes of pipelines used in thermal power plants. Residual life prediction is an effective guarantee to ensure the safety, utilization and benefit maximization of equipment. Based on the creep rupture test data of 2.25Cr-lMo heat-resistant steel in actual service for over 200 000 hours, the selection principle of TTP parameters and its influence on the accuracy of life prediction are analyzed by comprehensively considering the working stress and TTP parameters. The relationship curve family of Z-parameter method is used to characterize the vertical dispersion of pipeline durability data in different power plants. The stress-TTP-reliability curve for evaluating the reliability of life prediction is established, and the relationship between the predicted life of different power plant pipelines and the working state of the unit is obtained. The creep residual life of different power plant samples at 540 ℃/45.26 MPa is 1.725 6×10⁵ h and 3.378 8×10⁵ h respectively, and the predicted reliability reaches 99%, which provide maintenance suggestions for the operation reliability of power plant equipment.

The function of query and statistics of data is always the basis of production management and decision-making businesses. According to the results of information construction and applications for many years, the mode, function and performance of data query and statistics still do not satisfy the actual needs. A component for data query and statistics based on supervisory graph software is proposed and developed. Through the design of data path architecture, the optimization of query and statistics mechanism, the developed component has achieved personalized management, lightweight analysis and flexible query of real-time data. The query and statistic component and data link mode developed in this study have been tested and applied in practice. The results show that the function of data query and statistics achieves loose coupling with database. The component can support both the operation modes of C/S and B/S, and provide unified query and statistics of data through supervisory graph from multi-data sources and multi-level organizations. The efficiency of data query and trend query reaches or approaches the level of database native management tools, and is better than that of conventional supervisory information system (SIS) websites. The integration mechanism of data components based on graph with SIS data query and report system is proposed, which helps to reduce the repetitive cost of data use.

Numerical and experimental studies are conducted on convective heat transfer performance of carbon dioxide (S-CO₂) flowing in a heated vertical helically coiled tube under supercritical pressure. The influence of flow characteristics and structural characteristics such as heat flux q, mass flow rate G, pitch P, tube inner diameter d, and spiral radius R on heat transfer are discussed, and the sensitivity of each structural parameter is studied quantitatively. A closed-loop S-CO₂ test platform was built to conduct experimental research on the convective heat transfer performance of S-CO₂ in the helically coiled tube, and the accuracy of the numerical simulation is verified based on the experimental data. Finally, the heat transfer correlation of S-CO₂ is fitted. The research has laid foundation for the thermal design method of S-CO₂ spiral-wound heat exchanger, and has certain engineering application value for the application and promotion of the spiral-wound S-CO₂ heat exchangers in nuclear power and solar thermal power generations.

Driven by the “carbon peaking and carbon neutrality” goal, hydrogen blending and pure hydrogen combustion technology of gas turbines have received widespread attention. Producing “green hydrogen” from renewable energy and applying it for power generation is the development direction of the energy field in the future. However, the fluctuation of hydrogen source will inevitably cause the change of hydrogen blending ratio of hydrogen blended gas turbine fuel. Therefore, the dynamic response characteristics of the gas turbine are studied when the hydrogen blending ratio fluctuates. Taking an F-class heavy-duty gas turbine as the research object, a dynamic model is built by using the modular modeling method to analyze the response characteristics of key parameters of the unit and the safe operation of components when the hydrogen blending ratio fluctuates under different loads. The results show that when the hydrogen blending ratio fluctuates, the turbine inlet temperature (T₃) will fluctuate violently, and T₃ overtemperature will occur in the high load region, which will lead to the deterioration of the blade working environment and affect the safe operation of the unit. The larger the fluctuation of hydrogen blending ratio and the higher the power output, the more obvious T₃ overtemperature phenomenon. However, the fluctuation of hydrogen blending ratio has a relatively small impact on the compressor, and the compressor can still maintain a reasonable surge margin.

This paper proposes a multi-parameter collaborative monitoring system and method for degassed hydrogen conductivity based on the combination of double water membrane degassed method and electric regeneration ion exchange technology, which can quickly measure a number of key water quality indicators such as conductivity, hydrogen conductivity, degassed hydrogen conductivity and pH. It can make comprehensive evaluation of water quality, guide thermal equipment shutdown and startup. And it can adjust normal operating water conditions. It has a great significance for ensuring water vapor quality and thermal equipment corrosion, salt accumulation and scale formation. Double water membrane degassing technology is used to measure degassed hydrogen conductivity, which can effectively remove CO₂ from water. On this basis, a method of calibration degassed hydrogen conductivity measured by standard solution is proposed, so that the accuracy of the measured value can be effectively evaluated. This method has been applied to typical gas combined cycle units and heating units for on-site supervision. It proves that the method has high measurement accuracy, can quickly and comprehensively evaluate water vapor quality, and it can assist in solving various technical problems on site. Therefore, it has strong popularization and application value.

To study the thermal hydraulic characteristics of the printed circuit heat exchanger with rhombic fin channels, variations in thermal hydraulic characteristics on the hot and cold sides were analyzed by numerical simulation, with cold side inlet temperature of 313.15~353.15 K and hot side inlet temperature of 553.15~593.15 K. The working medium on the cold side and the hot side were S-CO₂ and gaseous CO₂ respectively. The comprehensive performance was compared between NACA0030 airfoil fin channels and rhombic fin channels. The results show that when the inlet temperature of S-CO₂ increases by 40 K, the total heat transfer decreases by 23.91%, and the pressure drop of hot and cold increases by 29.95% and 11.14% respectively. When the temperature of gaseous CO₂ increases by 40 K, the total heat transfer increases by 16.40%, and the pressure drop of hot and cold increases by 9.42% and 7.43% respectively.The inlet temperature of S-CO₂ has more obvious influences on the thermal hydraulic characteristics. The printed circuit heat exchanger with rhombic fin channels has less flow resistance and better comprehensive performance. The results have a certain reference significance for the design of printed circuit heat exchangers with discontinuous channels.