Under the background of wide application of low nitrogen and oxygen combustion technology and deep peaking technology, the high temperature corrosion failure of water wall tubes is more serious in service process. The high-temperature corrosion behavior characteristics of the boiler water wall tube and high-speed arc spraying PS45 coated tube from a power plant were comparatively investigated. Moreover, the corrosion surface morphology, corrosion products compositions and corrosion cross section characteristics were systematically analyzed by means of SEM, EDS and XRD. The results show that, the high-speed arc spraying PS45 coating can effectively improve the high temperature corrosion resistance of water wall tubes, and the thickness of the surface corrosion layer is small. In the process of high temperature service, the PS45 coating shows better corrosion resistance due to its high content of Cr and Ni, and the thickness of the surface corrosion products layer is thin. However, the microscopic pores between the coating particles will lead to intrusion of high-temperature corrosion reactions, and even cause direct corrosion of the water wall tubes at the coating/substrate interface.

Methane is one of the main components of atmospheric pollutants, which is challenging to be eliminated by catalytic oxidation under mild conditions because of its tetrahedral structure stability. In this work, the acidic sites of Pd-based catalysts are modified by introducing transition metals (Cr, Mo, W) to promote the cleavage of C-H bonds and therefore to enhance the catalytic oxidation performance of methane. The oxygen vacancies, acidity and redox property of prepared catalysts are systematically characterized by XRD, Raman, H₂-TPR and NH₃-TPD techniques. The results show that, the transition metal modification increases the acidic site of Pd catalysts obviously, and the modified PdM catalysts have a higher amount of oxygen vacancies. However, only Mo modified PdMo catalyst exhibits better redox performance, while Cr and W modified PdCr and PdW catalysts show slightly lower redox performance. The results of the methane oxidation reaction confirm that the PdMo catalyst with moderate acidic sites displays excellent performance in the methane oxidation reaction, and its T₉₀ decreases by about 150 ℃, while the PdCr and PdW catalysts with more and less acidic sites show lower methane oxidation activity. The results indicate that the number of acid sites and the redox properties of the catalyst jointly determine the methane oxidation performance. This conclusion provides critical insights for design and preparation of catalysts for complete oxidation of methane at low temperatures.

Partial heating supercritical carbon dioxide (S-CO₂) power cycle system is proven to be one promising option for waste heat recovery. By using LiBr-H₂O and NH₃-H₂O as working fluids, two types of novel combined power systems consisting of a parting pre-heating S-CO₂ cycle and different absorption power cycle (APC) systems are proposed. The detailed mathematical models of the proposed parting heating S-CO₂/APC systems are built and verified. Based on the results of single- and multi-objective optimization, the performances of the proposed S-CO₂/APC system and the standalone S-CO₂ system are compared from the perspective of thermodynamics and economics. The single-objective optimization study reveals that the net power output and net efficiency of the S-CO₂/LiBr-H₂O system and the S-CO₂/NH₃-H₂O system increases by 7.40% and 4.30%, respectively, compared with the standalone S-CO₂ system. The multi-objective optimization results show that, the S-CO₂/LiBr-H₂O system and S-CO₂/NH₃-H₂O system can obtain improvements of 7.94% and 5.13% in net efficiency as well as promotion of 12.35% and 9.02% in the specific investment cost respectively, indicating that the S-CO₂/LiBr-H₂O system has a greater potential. Exergy loss analysis reveals that the main exergy loss exists in the coolers and the heaters, and the proposed S-CO₂/APC systems can significantly reduce the exergy loss in the S-CO₂ cooler by about 45%.

The utilization hours of thermal power units continue to decline, and peak shavings become more frequent. Under this background, the existing ammonia injection mixing technology can no longer meet the new normal needs of coal-fired power plants, and ultra-low emissions put forward higher requirements for uniformity of the NH₃/NO_x molar ratio distribution at the SCR reactor inlet. The grid-type ammonia injection grid (AIG) and static mixer are optimized through CFD numerical simulation and physical model test. The design method and an anti-blocking nozzle are proposed to ensure the uniformity of ammonia distribution, adjustment flexibility, and anti-blocking performance of the ammonia injection grid. Moreover, a triangular large-scale flue gas self-mixing device is developed to improve the uniformity of the NO_x concentration field at inlet of the SCR reactor and enhance the load adaptability of the SCR denitrification device from the root. The relative standard deviation of NO_x distribution at the SCR outlet of a 600 MW unit under high, medium and low loads reached 8%~19% by using this technology, and the ammonia escape at full load decreased by 51%.

In the context of carbon peak and carbon neutrality, the development of coal-biomass coupling power generation is one of the important ways to accelerate the transformation and upgrading of electric power and realize low-carbon development of coal power. A coal-fired power generation system directly coupled with biomass combustion was designed for a 300 MW circulating fluidized bed (CFB) boiler, and the combustion characteristics of directly firing biomass with coal were studied by using the system. The results show that, this biomass direct combustion coupling system could run stably and reliably. When wood pellets was co-fired in the CFB boiler, with the increase of wood pellets’ blending ratio, the fly ash carbon content of the mixed fuel decreased, the CO emission reduced, and the burnout performance of the mixed fuel improved. After optimization on the boiler combustion and air distribution, the NO_x emission was slightly lower than that of pure coal burning. The pollutants test under typical conditions showed that, after adding wood pellets, the dioxin emission from boiler flue gas was 0.008 8 ng TEQ/m³ (standard condition, ϕ(O₂)=11%), and the dioxin emission in fly ash was 0.020 6 ng TEQ/m³. The total emission of heavy metals and harmful trace elements such P, As and Se from fly ash was 32.121 mg/l, and that from the bottom slag was 3.918 mg/L. The emission of harmful substances like dioxins and heavy metals in flue gas and fly ash all met the emission limits of national environmental protection standards.

Energy saving and emission reduction in road transport field is an important part of the strategy to achieve carbon neutrality. Heavy commercial vehicles have high power and range requirements, and the transition from conventional internal combustion locomotives to hybrids with waste heat recovery is of great significance in improving engine efficiency and reducing energy consumption. However, the waste heat recovery system integrated with hybrid power in current research mostly adopts a simple layout, and only recovers a single form of waste heat energy from the cylinder liner water or flue gas, which has a limited degree of enhancement to the overall efficiency of the vehicle. Therefore, a waste heat recovery system based on the organic Rankine cycle that can simultaneously recover the waste heat from flue gas and cylinder liner water and operate efficiently under full operating conditions is proposed. The system is coupled with a series hybrid power system and operates under high-speed and suburban road conditions, the performance of the organic Rankine cycle system and the improvement effect of the overall energy efficiency of the integrated system are then investigated. The results show that, under the premise of considering the weight of the waste heat recovery system, the waste heat recovery system improves the engine efficiency by 2.85% and reduces the overall fuel consumption by 6.78% under high-speed USHWY conditions. Under urban road UDDS conditions, it enhances the engine efficiency by 2.30% and decreases the overall fuel consumption by 6.43%. The above results demonstrate the system’s fuel-saving capability and application potential. It is found that the organic Rankine cycle system has a large inertia, and the long-term stable operation of the engine plays a decisive role in improving the output power and efficiency of the system, so the system is suitable for matching with high-speed operation of heavy-duty hybrid vehicles.

To study the effect of dust on performance of photovoltaic power generation, a laboratory bench was built to collect daily power generation data of clean and polluted photovoltaic strings while monitoring meteorological data to analyze the influence of dust accumulation and weather on power generation performance of photovoltaic modules. The results indicate that, the increase in PM_2.5 mass concentration in winter and the frequent occurrence of sandstorms in spring lead to a significant accumulation of dust on surface of the photovoltaic modules, resulting in a rapid increase in cumulative power generation losses. However, in summer, due to increased precipitation, dust is difficult to accumulate on photovoltaic modules, resulting in a slow increase in cumulative power generation losses. In addition, the DTW algorithm is employed to find similar days. Firstly, the entropy method is used to calculate the weights of each meteorological parameter. Then, the DTW values corresponding to each meteorological parameter on each historical day are calculated in reverse chronological order, multiplied by their weights, and added together to obtain the comprehensive DTW value for each historical day. By comparing the comprehensive DTW values of each historical day, the meteorological similar day that is closest to the current day is selected. In order to avoid extreme weather conditions, a portion of the dataset is selected as the validation set, and the criteria for finding similar days are optimized. The data from 9:00 to 15:00 each day is divided into three time periods for analysis, and the condition that the average solar irradiance is not less than 600 W/m² is set. After optimization, the evaluation index determination coefficient of the prediction model is 0.83, and the root mean square error is 0.22, indicating a significant improvement in prediction performance. Finally, the algorithm is used to develop a cleaning strategy for the photovoltaic power plant. After comparing the cumulative power generation loss with the cleaning cost, it is determined that the power plant should be cleaned every 28 days under long-term non rainfall conditions.

The microwave attenuation method is one of the common methods for online measurement of carbon content in fly ash in recent years. However, due to the differences in sampling locations and sampling devices of the fly ash, there is a large uncertainty in particle size of the fly ash, which results in a large error in the measurement of carbon content in fly ash. The existing carbon content fitting models are all based on the relationship between the attenuation of the characteristic frequency signal by fly ash and the carbon content of fly ash, which has problems such as large error and poor adaptability. In order to solve these problems, this paper proposes to use the time-domain main peak attenuation of the signal instead of the attenuation of the signal at the eigenfrequency as a method for online fitting of the carbon content in fly ash. To correct the error caused by the uncertainty of fly ash particle size, the effects of fly ash with different particle size ranges on the measurement of ash level and fly ash carbon content are compared on the basis of the study on ash level and carbon content measurement. The results show that, the peak attenuation of the signal in the time domain is used to calculate the carbon content, and the results are in good agreement with the actual values. For the same mass of ash samples in the waveguide, the particle size of the fly ash does not have any significant effect on the measurement accuracy of the ash level. When the microwave method is applied to measure the carbon content in the fly ash in the waveguide, for the same mass of ash samples, the attenuation of the fly ash on the microwave signal inside the waveguide decreases gradually with the particle size of the fly ash. Thus, the measured value of carbon content increases as the particle size of the fly ash decreases.

By taking the test bench of a micro gas turbine cycle system as the research object, a mathematical model for regenerative cycle system of the micro gas turbine is established. On this basis, the performance prediction and analysis for the regenerative cycle system is carried out. Considering the performance parameters of the system’s key components are presently unknown, the maximum likelihood estimation method is employed to estimate them by using the experimental data. The results show that, the error between the model predicted value and the experimental value is smaller than 3%, indicating the model can accurately predict the thermal performance of the cycle. Subsequently, based on the established model, a performance simulation of the recuperative cycle is conducted under various working conditions. The variation rules of power, generation efficiency, exhaust gas energy, and exhaust gas temperature with the changes of load and ambient temperature are obtained, and the compressor’s operating range is also obtained. The information regarding the key components of the microturbine and the performance characteristics acquired through this study can serve as valuable references for related research.

To investigate the potential of carbon emission monitoring technology in optimizing thermal power unit operations beyond the “double control” of emissions in thermal power enterprises, an F-class gas-steam combined cycle unit where a CO₂ monitoring system is installed at the tail chimney is selected to be discussed. Research is conducted using online fuel monitoring data from the front pressure regulating station and flue gas monitoring data from the rear chimney environmental protection measurement point. The results reveal that, in the high-load section, the flue gas monitoring carbon emission rate is consistently higher than the fuel monitoring rate, although both curves exhibit similar trends, indicating comparable yet offsetting data. For units operating at medium loads, atmospheric conditions are crucial. Elevated temperatures may increase heat loss, while reduced air pressure can minimize compressor energy consumption, thereby decreasing the unit’s instantaneous carbon emission intensity. Among various parameters, adjusting the turbine expansion ratio, compressor pressure ratio, and steam fuel power ratio could be effective strategies to minimize carbon emissions without altering the unit load.