During the low load operation of coal-fired units, the SCR denitration catalyst may be deactivated by ammonium bisulfate (ABS). The experimental tests are carried out on this phenomenon and the results show that: 1) with the flue gas temperature below the ABS condensation temperature, the catalyst will be deactivated due to the gradual deposition of ABS in the micropores. The ABS condensation temperature is inversely proportional to the micropore diameter, and the ABS concentration is positively related to the product of NH₃ and SO₃ concentrations in the flue gas; 2) the micropores with pore diameters of 2~20 nm are still the main structure of wide temperature denitration catalyst as well as the conventional catalysts, which cannot change its fate of ABS deactivation under low load; 3) the physical reversibility of catalyst ABS deactivation makes “combination of prevention and treatment” still the fundamental method to solve the ABS problem.

The traditional waste heat valve control technology is mainly divided into two methods, mechanism modeling and data-driven. However, in practical applications, the former is difficult to accurately describe due to the complex mechanism. The latter requires high data quality and full working condition samples, which is difficult to meet in a short time. Aiming at the above problems, a fusion-driven optimization method for waste heat valve control is proposed. Firstly, the mechanism knowledge and data knowledge are fused to construct a knowledge graph model based on fuzzy sets, and the valve opening knowledge is materialized. Secondly, the LSTM valve opening optimization model based on time protection mechanism is established, and the time protection mechanism algorithm is proposed to determine the optimal adjustment frequency of the valve. Finally, the recommended valve opening is obtained by knowledge reasoning. Through experimental analysis and verification, this method integrates qualitative knowledge such as waste heat recovery mechanism and quantitative knowledge such as equipment operation data. While improving the safety of equipment, the probability of generating high-temperature saturated steam enthalpy is increased by 94%, and the average daily increase is 8 640 kJ, which realizes the intelligent decision of waste heat recovery valve opening.

The floating platform undergoes six degrees-of-freedom of motion in the marine environment, making the flow field around the blade fluctuate drastically, and the changing flow field will have a huge impact on the dynamic response of the blade. A two-way fluid-structure interaction simulation of the NREL 5 MW wind turbine was carried out using the CFD-CSD coupling method. Based on this, the UDF technique introduced the floating platform motion to study the blade deformation and the overall torque and thrust changes under the surge, pitch, and yaw motion. The results show that the three typical platform motions of the surge, pitch, and yaw make the blade deformation amplitude increase, and the increase of flapwise and torsional deformation is more significant than that of edgewise deformation; the surge motion has the greatest influence on the blade deformation and aerodynamic performance, the maximum change range of torsional deformation can reach 70%, the peak values of the torque and thrust are increased by 30.51% and 11.75% respectively; the pitch and yaw motions reduce the average torque and thrust.

This paper explains the overall impact of the dual carbon strategy on coal power and the development problems it faces. The status quo and key technologies of clean emissions, energy conservation and carbon reduction, heat supply and efficiency improvement, and flexible operation of coal-fired power units are sorted out and analyzed, and the development prospects of coal power are prospected, and the conclusion is drawn that the development of coal power is positively viewed based on China's resource endowment and energy strategic security, and attention should be paid to the research and development and application of clean, efficient and flexible coal power technology, and the advantages of various new energy sources are complemented and dynamically coordinated to promote the steady development of new power systems.

An effective disposal method of municipal sewage sludge is burning sewage sludge together with coals in coal-fired circulating fluidized bed (CFB) boilers. At an appropriate weight ratio of sewage sludge in fuel blend, the co-combustion of sewage sludge and coals will not cause significant adverse effects on power plant production, and make use of the calorific value of sewage sludge. This study summarizes the progress of research and application in CFB boilers co-firing coal and sewage sludge, involving the emissions and controls of pollutants during the co-combustion of sewage sludge and coals, the weight ratio of sewage sludge in fuel blend under the reliable boiler operation, and sludge drying. The operational problems associated with the co-combustion of wet sludge and coals are analyzed. The applications of coal-water slurry suspension combustion technology and oxygen-enriched combustion technology in the disposal and utilization of sewage sludge are presented. The study points out that the drying and incineration of sewage sludge combined with advanced flue gas purification technology is one of the mature processes for the application of coal-fired CFB boilers in sewage sludge incineration, which can avoid the environmental impact of odours generated during the storage, drying and transportation of sewage sludge, and provide effective controls of a variety of pollutants. The conclusions of investigation and analysis can provide a reference and basis for the design and safe operation of CFB boilers co-firing coal and sewage sludge.

In order to accelerate the achievement of the goals of "carbon peaking" and "carbon neutrality", a series of laws, regulations, and institutional documents on greenhouse gas control have been introduced by the country, local governments, and industries. Nitrous oxide (N₂O), as a gas with strong greenhouse effects, has attracted increasing attention from researchers. This article summarizes the current research status of N₂O at home and abroad, compares the N₂O emissions of typical coal-fired boilers, analyzes the generation mechanism, influencing factors, suppression methods, and removal methods of N₂O during the combustion process, explores N₂O emission reduction strategies for coal-fired boilers, and provides suggestions. It is necessary to strengthen the formulation of N₂O related standards, research and development of new technologies, and demonstration applications for coal-fired boilers. Further research is needed on the influencing factors of N₂O, such as pressurized oxygen enrichment conditions and coal moisture content, to further improve the suppression and removal methods.

In order to ensure that the supercritical CFB boiler has good wide-load operation characteristics and the ability of deep peak regulation, the transient heat transfer characteristics between the working fluid and the water wall under the change of transcritical pressure are experimentally studied. Experiment adopted Φ25.0 mm×3.5 mm vertical upward tube, the near-critical steady heat transfer experiment and the transcritical pressure step transient heat transfer experiment were carried out under the experimental conditions of 20~23 MPa of pressure and 400~800 kg/(m²·s) of mass flow rate. The results showed that under the near-critical pressure, increasing the flow rate, reducing the heat flux on the inner wall, and reducing the pressure can reduce the dryness when the DNB heat transfer deterioration occurs, and increase the corresponding fluid enthalpy value, and delay the occurrence of the heat transfer deterioration. When the transcritical pressure step changes, the heat transfer deterioration may occur in the heating pipe, resulting in the wall temperature rising rapidly, but the temperature will fall back to the normal value with the increase of the flow rate. The heat transfer between the wall temperature rising point and the inner wall surface goes through the heat transfer deterioration stage, the subcooled boiling heat transfer enhancement stage and the single liquid phase heat transfer stage. The influence of each parameter on the heat transfer deterioration in the transcritical pressure step change experiment is the same as that in the near-critical steady state experiment. The decrease of flow rate and the increase of heat flux on the inner wall will advance the location of the heat transfer deterioration, and the wall temperature rise will be greater.

In the domestic large circulating fluidized bed boilers designed with side wall and back wall coal feeding system, there are generally prominent problems of coal feeding delay and uneven coal feeding in the actual operation process. By analyzing the coal feeding delay problem of large CFB boiler units and the operation characteristics of the existing coal feeding system, the quantitative calculation method of coal feeding delay problem of large CFB boiler coal feeding line is put forward. Based on the case of a supercritical 600 MW CFB boiler coal feed line, the coal feed delay characteristics of the coal feed line under the condition of wide load and rapid peak regulation are obtained. The calculation results show that the coal feed delay problem is common in the variable load operation process of large CFB boiler units, which will lead to a certain degree of uneven coal feed. The variable load range, variable load rate and the number of coal feed ports on the single feed line are positively correlated with the severity of the delay problem. The calculation method and analysis results can provide design basis and technical reference for large CFB boiler coal feed line to adapt to wide load and fast peaking operation.

In order to provide methodological guidance for the load optimal distribution of thermal power units under the condition of deep peak regulation, the objective functions of optimal load distribution under medium-high load and low load are established respectively, and the load optimal distribution under different conditions is studied. The k-means clustering algorithm is used to process the data and the coal consumption characteristic curves of two units under medium-high load and low load are fitted. The objective function of load distribution is established to compare the coal consumption before and after optimization under static load distribution, incremental load distribution and continuous variable load conditions. After setting the total load instructions of the two units under the condition of deep peak shaving, the coal consumption of the two schemes of load average distribution and optimal distribution is compared. The results show that the clustering-based objective function models of optimal distribution under medium-high load and low load established by the coal consumption characteristic curve are reliable, whose optimization effect is remarkable under the condition of deep peak regulation. The k-means clustering algorithm can be used to optimize the load distribution of thermal power units and provide reference for the study of load optimal distribution under the condition of deep peak regulation of thermal power units.

Flue gas recirculation (FGR) is an important technical mean to improve the safety of circulating fluidized bed (CFB) boiler and reduce the generation of NO_x under low-load operation. In the present work, the relationships between temperature distribution of the boiler, NO_x, CO mass concentration and O₂ volume fraction of the flue gas at furnace outlet, the combustible matter content of fly ash and bottom slag and the flow rate of FGR under the load of 20%, 30% and 40% BMCR (boiler maximum continuous rating) were studied using one-dimensional chamber CFB combustion quasi-static model at a supercritical 350 MW CFB boiler. The results show that both the bed temperature and furnace exit flue gas temperature decrease with the increase of FGR flow rate, which the former decreases less than the latter. The temperature difference between the upper and lower furnace gradually decreases with the increase of FGR flow rate, which is more significantly affected by FGR flow rate at lower loads. The NO_x mass concentration of flue gas at the furnace exit shows a trend of decreasing first and then increasing with the increase of FGR flow rate, and the existence of the optimal FGR flow rate can make the unit operation economically and environmentally friendly. In addition, with the increase of the FGR flow rate, the CO mass concentration at the furnace outlet, combustible matter content of fly ash and bottom slag shows an increasing trend. The FGR significantly reduces the primary air oxygen volume fraction while ensuring that the fluidized air flow rate in the dense phase area is always higher than the protection value, which ensures the operation safety of the boiler under low load furtherly.