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.

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.

In 2021, China launched its national carbon market. To enhance the accuracy of carbon trading, it is essential that carbon emission data are measurable, reportable, and verifiable. Against this backdrop, online monitoring systems for flue gas have gained significant attentions as a method of quantifying carbon emissions. The basis for the effective work of continuous emission monitoring systems is the accurate measurement of flue gas flow. However, the challenge in accurately measuring flue gas flow rates is significantly heightened by the large size of power plant chimneys and the complexity of the gas flow characteristics within them. This paper focuses on analyzing the current research status of Pitot tube flowmeters and ultrasonic flowmeters in large-scale duct flow measurement, and provides a detailed introduction to gas flow measurement technologies for large-scale ducts. Additionally, it introduces an independent flow measurement method, namely the tracer gas dilution method, and discusses its current development and potential as a flow calibration method.

In electric power ancillary service market, coal-fired thermal power units are facing new opportunities and challenges in participating in frequency regulation auxiliary services. During operation of large-capacity (ultra) supercritical coal-fired unit boilers, the energy storage is limited and the AGC frequency regulation response performance are difficult to adapt to the increasing frequency regulation demand of the ancillary service market. To solve these problems, the influence of different energy states of grid and source on frequency regulation is analyzed, and a self-adaptive frequency regulation control strategy based on grid-source operation state is designed. This strategy is based on the boiler energy storage state and the grid frequency regulation demand, and can adaptively undertake the AGC frequency regulation task in the frequency regulation ancillary service market. It fully exerts the frequency regulation potential of the unit, and is beneficial to fast energy balance and parameter recovery stability of the unit itself, which realizes the grid-source goal coordination of the safe and stable operation of the unit and the improvement of the comprehensive frequency regulation performance index of the unit.

Aiming at solving the problem of complex and uneven flow field inside the coal pulverizer, a complete model of medium-speed coal pulverizer was established. The CFD software was used to solve the internal flow equation of the coal pulverizer. Moreover, DPM iteration was used to obtain particle flow parameters, and the internal flow of the medium-speed coal pulverizer and distribution characteristics of outlet air-powder at different rotation speeds of dynamic classifier were explored. The results showed that, the distribution characteristics of primary air at four pulverizer outlets were good and consistent with the test results. When the powder diameter was small, the powder mass flow deviation at four pulverizer outlets was small, and the fluctuation was not obvious with the increase of the rotation speed of the dynamic classifier. With the increase of powder diameter, the motion trajectory of powder showed a wall adherent motion, and the powder mass flow deviation at four pulverizer outlets gradually increased. Furthermore, for coal particles with large diameters, with the increase of the rotation speed of the dynamic classifier, the powder mass flow deviation at four pulverizer outlets gradually decreased.

Flue gas flow is one of the key factors affecting the accuracy of carbon monitoring, and the complex flow field environment with uneven velocity distribution and changing with unit load is the main factor impeding the accurate measurement of flue gas flow. By taking a chimney inlet flue of a 660 MW unit in a power plant as the research object, the influence of the number of points and the layout of the process on measurement accuracy of the flowmeter with four different measurement principles was compared and analyzed based on numerical simulation results of the flue gas flow field. The results show that, the multipoint Pitot tube flowmeter has better adaptability to the complex flow field environment compared with the matrix flowmeter. When the number of measuring points is 28, the deviation of the matrix flowmeter is 1.54 times that of the multipoint Pitot tube flowmeter. The measurement accuracy of the light scintillation flowmeter is greatly affected by the elevation of the installation position, with the maximum deviation being 23.3 times the minimum deviation. This indicates that the light scintillation flowmeter has poor adaptability to complex flow field environments. The ultrasonic flowmeter can be installed obliquely and in multiple channels, with a more flexible and varied process layout, significantly improving its adaptability to complex flow fields. The dual-channel arrangement can control the deviation within ± 1.5%. The research results provide important theoretical basis and data support for the selection of flow meter equipment and process design, and have important theoretical research and engineering application value.

The coupling of coal-fired units with molten salt electric heater systems can significantly improve their frequency regulation and peak shaving capabilities. On the basis of Modelica language, a dynamic model of the molten salt electric heater is established and the experimental verification is completed, it reveals the dynamic characteristics of the molten salt electric heater under the disturbance of molten salt flow rate and unit AGC load. A temperature control method of “feedforward+PID” regulation is proposed based on its dynamic characteristics, and the characteristics of electrical load and thermal parameter changes during AGC regulation of coal-fired units assisted by molten salt electric heaters are calculated and analyzed. The results indicate that, configuring a 10 MW molten salt electric heater can increase the AGC variable load rate of a 660 MW coal-fired unit by 340%, and the proposed control method can maintain the stability of thermal parameters of the electric heater.

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 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.

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.