The structural characteristics of once-through steam generators and throttling assembly in the demonstration project of high-temperature gas cooled reactors were introduced, and the reasons and influencing factors of sediment blocking the throttling holes were analyzed. Moreover, the deposition law of corrosion products on the throttling holes of steam generators in high-temperature gas cooled reactors was studied by dynamic cyclic tests at high temperatures and high pressures, including the effects of different iron sources, iron mass fractions, flow rates, and pH values on throttling hole deposition. The results show that, free iron is the main precursor of throttling pore sediments. The phenomenon of throttling hole sediment increases with the iron mass fraction in water. With the increase of local flow velocity, the sedimentation rate of throttling hole increases at first and then decreases, and there exists a maximum deposition velocity range. As the pH value of the water increases from 9.1 to 9.7, the phenomenon of throttle hole deposition intensifies. It is found that appropriately reducing the pH value of feed water and optimizing throttle hole structure size (adjusting flow rate) are effective methods to inhibit the deposition and blockage of steam generator throttling components.

As a core control parameter in peak regulation via banking fire, the banking fire duration directly affects the safety and economic efficiency of unit operation. However, due to the complex coupling and dynamic characteristics of thermodynamic parameters during the banking process, it is difficult for existing calculation methods to achieve efficient and accurate calculations. An energy-balance-based method was proposed for banking fire duration calculation in subcritical CFB boilers. A dynamic equilibrium model was established for heat storage and turbine heat utilization and heat dissipation during banking fire, deriving heat storage and release formulas for key heat sources, such as bed material, refractory, metal heating surfaces, working fluid, and carbon combustion. Finally, the banking fire duration was obtained. Taking a 300 MW sub-critical CFB unit as an example, the absolute error between the calculated value and the measured value is controlled within 5 minutes, and the relative error is less than 10%, which can meet the engineering requirements of fire-hold peak-shaving. The results demonstrate that, in terms of heat storage, the heat storage of metal heating surfaces contributes 35%~41% to the banking fire duration. The contributions of bed material and refractory are each approximately 20%, and the contribution of carbon combustion in the bed material is 10%~15%. The contributions of gas and working fluid heat storage are less than 2% and can be neglected. In terms of heat consumption, heat consumption for power generation accounts for the highest proportion, and it increases with the electrical load. The heat required for the steam turbine to overcome its own rotational resistance accounts for approximately 20%, and the proportion of heat dissipation of the unit is less than 5%. By raising the initial temperature of banking fire, increasing the amount of bed material, using coal with high volatile content, and reducing the electrical load of the unit during banking, the banking fire duration can be significantly prolonged. Notably, the banking fire duration exceeds 2 hours only when the average electrical load during banking is reduced to 1% of rated load.

To address the challenges of low diagnostic accuracy and poor interpretability for minority fault classes caused by imbalanced data distribution in coal mill pulverizing systems of coal-fired power plants, a fault diagnosis method integrating SMOTE data enhancement, Dirichlet prior smoothing, and Bayesian networks is proposed. The SMOTE technology expands the feature space of minority fault samples to alleviate data scarcity, while Dirichlet prior smoothing optimizes conditional probability estimation in Bayesian networks, resolving zero-probability issues caused by insufficient samples. A hierarchical Bayesian network architecture is constructed by incorporating domain knowledge and data-driven structure learning, enabling a dual-mode diagnosis strategy that combines rapid fault node inference with indirect attribute node analysis. The experimental results based on real industrial data demonstrate that the proposed method achieves high diagnostic accuracy and interpretability under imbalanced data scenarios. The solution provides real-time performance, precision, and transparency for coal mill fault diagnosis, offering significant engineering value.

The RNG k-ɛ model was used to numerically simulate the flow and heat transfer characteristics of supercritical CH₄-H₂ mixtures in horizontal pipe. The thermal physical properties of the CH₄-H₂ mixtures with hydrogen ratio of 0~30%, as well as the heat transfer process of the CH₄-H₂ mixtures with hydrogen ratio of 0~15% in the horizontal tube were analyzed. The influences of mass flow rate (150~250 kg/(m²·s)) and heat flux density (150~250 kW/m²) on flow and heat transfer of the mixed working fluid with hydrogen ratio of 10% were studied. The results show that when the hydrogen ratio increases from 0 to 30%, the pseudo-critical temperature of the mixed working fluid increases slightly from 190.4 K and then sharply decreases to 181.7 K, and the pseudo-critical pressure increases from 4.3 MPa to 12.3 MPa. With the increase of the hydrogen ratio (0~15%), the heat transfer between the fluid and the wall is strengthened. The increase of mass flow rate strengthens the heat transfer capacity of the mixed working fluid and weakens the heat transfer deterioration caused by buoyancy effect. The increase of heat flux strengthens the heat transfer degree of the wall under the mixed working medium, and weakens the heat transfer degree of the upper wall due to the advanced appearance of the gas-like film. Increasing the mass flow rate and heat flux density can enhance the heat transfer to varying degrees. The research can provide theoretical reference for mixed working medium heat exchangers in hydrogen-doped natural gas transmission and power circulation systems.

At home and abroad, the locations suitable for developing concentrated solar power are mainly in desert areas. Dust in these environments may accumulate on the heat absorbing surfaces of the receiver in the solar power tower system, resulting in failure of the wall and coating of the pipe. To protect the heat absorbing walls, a coupled heat transfer model is developed for the sand-pipe, and the effects of several parameters on the wall temperature are investigated, such as the dust particle diameter, the contact areas between the dust and tube wall, and the concentrated solar energy flux density. The results show that, the influence of dust particles on the temperature of the heat-absorbing pipes is limited to a small area, but it will cause local high-temperature hot spots on the pipes. With a high concentrated solar energy flux density, a large dust particle diameter and a small contract area between the dust particles and the heat-absorbing pipes, both the temperature of the dust particle and the hot spot at the pipes will increase greatly. The temperature of the dust particles could exceed their melting point, forming calcium-magnesium-aluminum-silicate (CMAS) deposits, which means the receiver is at risk of CMAS corrosion. Meanwhile, the high-temperature hot spots on the heat-absorbing pipes will affect the local thermal stress distribution, exacerbating the damage to the receiver. Therefore, during actual operation, the cleanliness of the heat-absorbing pipe walls should be regularly inspected to avoid the accumulation of large-sized dust particles. The research results can provide technical guidance for the operation and maintenance of the receiver in the concentrated solar power system.

To construct a prediction model for carbon emission from coal-fired power plants and address the problem of general lack of real-time elemental analysis for coal entering the furnace of coal-fired units, according to the in-furnace coal quality information of a million kilowatt unit in 2023, the low calorific value, volatile matter, and sulfur content were used as the basis for coal quality classification, K-means++ algorithm was used for clustering analysis, and correlation analysis was used to screen the input parameters of the carbon emission prediction model. The BP neural network suffered Bayesian optimization was used to construct carbon emission prediction models for each cluster data after clustering, and the models were tested for working conditions such as load increase and decrease. The results show that, the accuracy of the coal quality clustering model in predicting carbon emissions increases significantly. Compared with the non clustered model, the optimal cases of average root mean square error and average relative error reduce by about 53.4% and 49.2%, respectively. Especially under variable load conditions, the predicted results are more in line with the actual values. This indicates that the proposed method can not only effectively predict the carbon emissions of coal-fired power plants, but also maintain high accuracy in the case of complex and variable coal quality.

Based on the concept of high efficiency of gas turbine variable back pressure operation regulation, a high back pressure gas turbine combined cycle power generation system scheme is proposed, in which a pre-compressor and an expander are set in front and behind the main top cycle respectively to maintain and regulate the gas turbine exhaust pressure. Key parameters of the combined cycle are designed based on the initial parameters of the F-class gas turbine, and the case and characteristic analysis are carried out for the temperature of recirculated gas (divided into two conditions: cooling to normal temperature and not cooling), the main top cycle pressure ratio and the gas turbine back pressure. The results show that, the combined cycle efficiency of the recirculated flue gas cooling is not as high as that of the non-cooled flue gas cooling, which is 58.07% and 58.94% when the turbine back pressure is 0.30 MPa. The exergy loss rate of the main compressor is lower because the exit temperature of the main compressor is higher when the recirculated flue gas temperature is higher. When the gas turbine back pressure is 0.30 MPa, the maximum pressure ratio of the combined cycle system efficiency is 17.0, the corresponding combined cycle efficiency is 58.97%, and the specific work is 563.87 kJ/kg. Considering the specific work comprehensively, the recommended main top pressure ratio is 15.4, and when the turbine back pressure is from 0.03 MPa to 0.35 MPa, the variation range of the combined circulation efficiency under the two conditions is about 56.00%~58.57% and 55.81%~59.12%, respectively, which increases at first and then decreases, and the variation range of the combined efficiency is not large at high back pressure. At the same time, based on the practical engineering application, the design of a single waste heat boiler is considered, and its thermal characteristics and possible flexible, low-cost and efficient utilization of renewable energy are analyzed, which provides a new system scheme reference for the flexible and efficient modern combined cycle with multi-energy complementarities.

As the core of thermal power units, the operation efficiency of the direct air cooling system is significantly restricted by the geographical location of the power plant and the surrounding environmental parameters. Taking the direct air cooling system of a power plant as the prototype, a three-dimensional numerical model of the air cooling system and the surrounding buildings and mountain environment is established, and the composite wind prevention measures for the windward side of the air cooling island or the units with unfavorable heat transfer are proposed. The windproof measures and optimization mechanism of the direct air cooling system with strong applicability and good effect are explored, and the influence of air flow field reconstruction inside and outside the air cooling unit on the cooling performance of the direct air cooling system is analyzed. The results show that the internal and external wind-proof measures of the direct air-cooled unit can effectively improve the thermal performance of the unit. When the wind speed is 5 m/s, the large cross wall windshield has a good effect on improving the heat transfer performance of the air-cooled island. The frontal wind speed of the radiator increases by 0.24 m/s, and the surface temperature of the radiator reduces by 2.40 ℃. After the reconstruction of the air flow field inside and outside the air cooling unit, the average surface temperature of the radiator in the direct air cooling system reduces by 5.77 ℃, and the back pressure reduces by 2.92 kPa. The reconstruction of the air flow field inside and outside the air cooling unit can significantly improve the cooling effect of the direct air cooling system and improve the operating performance of the cold end system of the power station. In the future, the optimization design of the diversion device of the direct air cooling system can focus on the improvement of the uniformity of the flow field.

Ammonium bicarbonate is a potential denitrification reducing agent that can efficiently produce ammonia gas through direct solid pyrolysis. The pyrolysis reaction of ammonium bicarbonate solid is numerically simulated, a pyrolysis ammonia production system suitable for coal-fired power plants is designed, and the economic feasibility of the ammonium bicarbonate pyrolysis ammonia production process is analyzed. The simulation results show that, the pyrolysis process of ammonium bicarbonate favors the atmosphere pressure and the conversion rate of pyrolysis rapidly increases when the reaction temperature is above 110 ℃. The pyrolysis system of ammonium bicarbonate for a 660 MW unit has been designed and calculated. An external heating pyrolysis reactor is adopted to realize the utilization of waste heat and stable solid feeding. Steam or flue gas from the coal-fired power plant is used as the heat source for pyrolysis. At 110 ℃, a conversion rate of 95% can be reached within 10 minutes for ammonium bicarbonate feed. Compared with the urea hydrolysis process, the equipment cost, land occupation and operating cost of the ammonium bicarbonate solid pyrolysis process all significantly reduce, showing good prospects for promotion and application.

The fuel adaptability of a certain type of gas turbine combustion chamber is systematically investigated in response to the characteristics of blast furnace gas composition and its significant fluctuations in its calorific value. By coupling the detailed chemical reaction mechanism with numerical simulation methods, the comprehensive performance characteristics of the gas turbine combustion chamber under different calorific values and composition conditions were obtained, with a focus on analyzing the distribution of temperature and concentration fields and their influencing mechanisms. The results show that, under the same initial conditions and fuel calorific value, as the volume fraction ratio of H₂ to CO in the gas increases, the average temperature at the combustion chamber outlet decreases from 1 769.35 K to 1 710.11 K, the temperature distribution coefficient decreases from 0.044 to 0.016, the NO_x emission concentration at the outlet decreases from 7.56×10^–6 mol/m³ to 1.49×10^–6 mol/m³, and the CO emission concentration decreases from 993.98×10^–6 mol/m³ to 421.95×10^–6 mol/m³, and the combustion efficiency increases from 98.48% to 99.14%. As the volume fraction ratio of CO₂ to N₂ in the gas increases, the average temperature at the combustion chamber outlet decreases from 1 739.30 K to 1 694.99 K, the temperature distribution coefficient fluctuates in the range of 0.032~0.045, the NO_x emission concentration at the outlet decreases from 3.18×10^–6 mol/m³ to 1.39×10^–6 mol/m³, the CO emission concentration increases from 633.73×10^–6 mol/m³ to 832.45×10^–6 mol/m³, and the combustion efficiency decreases from 98.89% to 98.56%. In addition, as the fuel calorific value increases, the average temperature at the combustion chamber outlet significantly increases from 1 587.30 K to 1 862.39 K, the temperature distribution coefficient shows a downward trend, the NO_x emission concentration increases from 0.29×10^–6 mol/m³ to 18.66×10^–6 mol/m³, the CO emission concentration increases from 459.25×10^–6 mol/m³ to 1 030.61×10^–6 mol/m³, and the combustion efficiency decreases from 99.14% to 98.33%. Finally, 20 sets of data are selected for nonlinear surface fitting. For the blast furnace gas with a heat value range of 3~5 MJ/m³, all the the R² values of the fitting formula are greater than 0.90, indicating this formula can provide a theoretical basis for the control of low-heat-value fuels in gas turbine combustion chambers.