The existing thermal power flexibility renovation plan is difficult to eliminate the thermal system life loss and unit safety operation risks caused by frequent and rapid load changes. In order to effectively ensure the safety, economy, and health of thermal power units participating in grid peak shaving, a full capacity and long life peak shaving technology scheme for thermal power units based on the coupling of solid oxide electrolysis cell hydrogen production technology (SOEC) and burner local oxygen enriched combustion technology (OEC) is proposed and constructed. Taking an ultra supercritical 1 000 MW secondary reheat unit as an example, energy efficiency calculation is conducted on the SOEC-OEC system participating in power grid peak shaving at a depth of 70%~100%, and the results are compared with that of the conventional alkaline water electrolysis hydrogen production (ALK) system. The results show that, the energy efficiency of the extraction electrolysis hydrogen production system in SOEC-OEC is as high as 49.86%, which is about 26.40% higher than that of the ALK system. The oxygen enriched combustion system can reduce the boiler exhaust gas by up to 23.7%, reduce the unit coal consumption by 2.83 g/(kW·h), and reduce the carbon emissions by about 2.82 t/h. In addition, the SOEC-OEC system can also bring excess peak shaving subsidy benefits, hydrogen sales revenue, oxygen enrichment and coal saving and carbon reduction revenue, as well as equipment life extension benefits to the unit, fully ensuring the economic efficiency, safety, and environmental protection of the thermal power peak shaving process.

The anti-freezing operation parameters of indirect air-cooled finned bundle are insufficient at present. To solve this problem, this research firstly concludes the anti-freezing model of finned tube bundle, including the thermal equilibration equations, water side and air side transport equations, as well as anti-freezing constrains. Secondly, based on the co-current and counter-current air-cooled finned tube bundles, the critical anti-freezing characteristics and margin are analyzed. Then, the critical values are discovered for finned tube bundles with middle inlet, left inlet and side inlet patterns. The research shows that, as the ambient temperature or inlet water temperature reduces, as well as the ambient wind increases, the critical anti-freezing water flow rate ascends. Besides, when the inlet water temperature decreases, the wind effects get intensified. The anti-freezing performance of counter-current finned tube bundle is inferior to that of the co-current type, meanwhile the difference becomes expanded if the wind increases or water inlet temperature decreases. The effects of inlet water temperature elevation on anti-freezing margin can be classified into three levels, which are termed as obvious range (0 ℃, 10 ℃], slow range (10 ℃, 20 ℃], and stable range (20 ℃, 40 ℃]. Therefore, power plants should not always increase the water flow rate for anti-freezing operation. The air-cooled finned tube bundle with middle inlet pattern has better anti-freezing performance than others, so it’s suggested preferentially for coal-fired or nuclear power plants. This research may provide guidelines of anti-freezing operation for dry-cooling power stations in China.

The health status of gearbox directly affects the power generation of wind turbine. In order to achieve early warning of gearbox fault status in engineering practice, a K-means clustering algorithm based on improved lion swarm optimization was proposed. The supervision mechanism and the sine and cosine optimization algorithm considering nonlinear weights are introduced into the lion swarm algorithm, and then the optimized lion swarm algorithm is used to iterate the lion king position. By selecting the optimal solution as the clustering center of the K-means algorithm, the problem of strong dependence of conventional clustering algorithms on the selection of initial clustering centers is solved. The UCI data are selected for comparative verification of the algorithm, and the results show that, the K-means clustering algorithm based on the improved lion swarm optimization has achieved a better improvement in classification accuracy and stability. This algorithm is then applied to comparative test of gearbox vibration acceleration effective value for four wind turbines of the same type in a wind farm. It is found that the distribution of classification centers determined by this algorithm is consistent with the actual operating status of the gearbox, and agrees well with the vibration energy distribution corresponding to different states of the gearbox specified in the standard, indicating that the algorithm can realize early fault warning of wind turbine gearbox.

A new kilowatt-class methane reforming hydrogen production reactor is designed, using solid oxide fuel cell exhaust gas for heat supply. The system can make full use of the waste heat and combustible components in the exhaust gas to form a compact and efficient natural gas power generation system. Computational fluid dynamics was used to numerically simulate the combustion and reforming reactions in the reactor. The results show that the solid oxide fuel cell anode and cathode exhaust gases can be stably burned in the reactor to form a high-temperature flame of 1 486 ℃ to provide heat for the methane steam reforming reaction. In the reaction tube, the concentrations of H₂O and CH₄ continue to decrease along the way. Due to excess water vapor, the H₂O volume concentration at the outlet is 35%, the hydrogen concentration volume fraction is 45%, and the methane conversion rate reaches 90%. Nickel catalyst has a high thermal conductivity, so the temperature difference between the inside and outside of the reaction tube is less than 15 ℃. At the same time, experimental research was used to obtain data such as temperature, methane concentration and methane conversion rate in the reactor. The simulation results were compared to verify the accuracy of the numerical simulation.

The accurate measurement of solar absorber coating absorption is of great significance to the evaluation and optimization of the absorber performance. At present, the experimental researches of absorber coating absorption are mostly limited to the flat metal substrate. By taking the cylindrical tube of tower solar molten salt absorber, two widely used measurement methods for testing the absorption of curved surface coatings are proposed. The equipment preparation of Blu-Tack method is simple but the operation is complex, and the equipment preparation of diffuse reflection box method is complex but the operation is simple. The two methods isolate the interference of ambient light during the measurement process, and obtain the measured absorption of various coatings attached to the surface of plate and tube. The fitting curve is then established by the corresponding relationship between the absorption of different coatings on the plate and tube, so as to modify the measured data to obtain the absorption of the absorber tube coating. The results show that, the accuracy of the fitting curve R²≥0.995, the maximum relative error is 13.39% when the absorption of 2.5 cm diameter tube is measured directly under unshaded conditions, and the relative error reduces to 0.27% and 0.45% by using Blu-Tack method and diffuse reflection box method, respectively. The difference of the relative error of each point of the two methods is less than 0.30%. The greater the coating absorption, the less the influence of each factor on the measurement results. In the test method of Blu-Tack, the larger the tube diameter, the smaller the measured absorption.

In order to study the microstructure properties of different regions of welding heat affected zone (HAZ) of 1 000 MPa grade ultra-high strength steel, the samples of test steel at different peak temperatures of thermal cycle were prepared by welding thermal simulation technique, and the impact toughness of different regions of HAZ was studied through Charpy impact tests. The results showed that, in the subcritical region of HAZ (SCHAZ), the intercritical region of HAZ (ICHAZ) and the fine-grained region of HAZ (FGHAZ), the samples had relatively high impact absorption energy, crack propagation energy and dynamic impact toughness, and a large area of fiber region and shear lip formed on the fracture surface. Toughness dimples of different sizes can be seen at the microscopic level. The samples had good impact toughness. In the coarse-grained region of HAZ (CGHAZ), all impact data of the samples sharply decreased, and the fracture showed a macroscopic brittle fracture, almost all of which are radiological regions. At the microscopic level, it showed quasi cleavage fracture characteristics, indicating that the resistance to crack propagation decreased, and the time for stable propagation decreased after crack initiation, and the instability propagation was fast. The impact toughness of the samples deteriorated, and the CGHAZ region was a ductile valley region in HAZ. The results showed that the coarse grains and the coarse M-A island were the main causes of embrittlement in the CGHAZ region. The conclusion lays a theoretical foundation for the selection, development and engineering application of 1 000 MPa grade ultra-high strength steel in hydropower projects.

To address the mismatch between electricity supply and demand caused by the intermittency and fluctuation of renewable energy sources, a combined cycle energy storage and power generation system incorporating a closed supercritical carbon dioxide (S-CO₂) cycle and a high-temperature heat pump is proposed, which is an innovative exploration of the Carnot battery form. Through energy exchange via molten salt heat storage and water cold storage devices, this system efficiently integrates the heating process of the heat pump cycle with power generation process of the S-CO₂ cycle, which achieves a favorable round-trip efficiency for the energy storage power generation system. Simulations are performed to calculate the typical operational parameters and thermodynamic performance of the combined cycle, and to analyze the influence of main parameters of the S-CO₂ cycle on the overall efficiency of the system. The results indicate that, increasing the inlet temperature of the expander aids in enhancing the overall cycle efficiency, achieving an optimal electrical-to-electrical efficiency of 62.8%, while reducing the demand for heat storage molten salt. Elevating the inlet gas parameters of the main compressor will lead the system efficiency to reach a peak value, beyond which the overall cycle efficiency no longer increases. The optimal bypass ratio for the main recompressor is 0.35, which allows the system to achieve optimal efficiency. The optimal operating conditions of the S-CO₂ cycle system are identified, offering an electrical-to-electrical efficiency that is 7.98% higher than a reversible Brayton system under the same conditions.

The gas cooler, as an essential heat exchange device in Brayton cycle system, has a significant influence on structural compactness and operational efficiency of the cycle system. The performance and influencing factors of a cross flow printed circuit heat exchanger (PCHE)-plate-fin gas cooler are analyzed. A calculation model is established for this type of heat exchanger, and a MATLAB program is written to verify its reliability. Based on this, the coolers are designed, and the power density is above 1 MW/m³, indicating the cooler is compact heat exchanger. Moreover, the design and performance analysis of the heat exchanger are carried out under varying working conditions, and the change law of the pressure drop and heat transfer performance of the gas cooler with the inlet state of the circulating working medium and cooling air is given. The pressure drop and heat transfer performance are compared when the working medium of the Brayton cycle is supercritical carbon dioxide, nitrogen and air. The results show that, the change of cold and hot fluid mass flow has the most obvious influence on the heat transfer performance. The research has reference significance for the design and operation of Brayton circulating air cooling heat exchangers.

Building an efficient and pollution-free power generation system is an effective means to solve the current energy shortage and environmental pollution problems. By taking the C65 micro gas turbine produced by Capstone Company as the core power generation component, and coupling with the thermochemical process of solar powered ammonia decomposition to produce hydrogen, this article achieves multi-energy complementarity between renewable energy and ammonia chemical energy. The organic Rankine cycle is used as the bottom cycle to recover the waste heat from the flue gas generated by the micro gas turbine and generate electricity, achieving cascade energy utilization. A detailed simulation process is constructed in the chemical simulation software Aspen Plus. The results show that the complementary use of solar energy and ammonia has improved the calorific value of the generated hydrogen rich synthesis gas. The output power of the micro combustion engine is 89.95 kW, which is 24.95 kW more than the C65 micro combustion engine in the reference system. The electrical efficiency of the system under design conditions reaches 44.81%, and the thermal efficiency is 47.97%, which are 8.51 percentage points and 9.67 percentage points higher than that of the reference system, respectively. The component having the largest exergy loss in the system is the combustion chamber, accounting for 41.67% of the total damage, followed by the evaporator and regenerator, accounting for 14.31% and 11.15%, respectively. Sensitivity analysis shows that the electrical efficiency and thermal efficiency of the system decrease and increase with the increase of solar energy collection, respectively. The research results provide a reference for a distributed micro turbine power generation system using ammonia gas as fuel and coupled with solar energy.

A method was proposed to solve the problem of oil sludge treatment environmentally by sending the pretreated oil sludge into a 330 MW pulverized coal boiler co-firing with coal. The combustion characteristics of the oil sludge were studied by thermogravimetric analysis, and it was proved to be easy to ignite with a high calorific value close to coal, which could improve the boiler’s low-load stable combustion ability. Numerical simulation results showed that the combustion center shifted downward slightly after the oil sludge was sent into the boiler, while the NO_x content decreased. The experimental results proved that the minimum stable combustion load rate can be 20.00% by the benefit of oil sludge co-firing. The temperature at the coal-burner layer increased by 30~50 ℃ and the carbon content of the fly ash decreased from 4.79% to 3.80%. The fire detection analog signal of the coal burner was found to be more stable which validated the positive effect of the oil sludge co-firing at low load condition. The boiler efficiency increased by 0.23 percentage point which reduced the net coal consumption rate by 0.7 g/(kW·h). Moreover, about 3.7 t/h coal was saved at 120 MW load. The method was verified to have a significant energy-saving effect.