To improve the flexibility of coal-fired units, boilers need to have good controllability and the ability to adapt to rapid load changes. The flexibility of the boiler is closely related to the performance of the control system, which is designed according to the dynamic characteristics of boilers. To study the dynamic characteristics of boilers, a dynamic model of a supercritical 660 MW coal-fired boiler is built in the Dymola platform. The results show that the response time of steam temperature is longer than that of steam flow. When the feedwater temperature, feedwater flow, and fuel quantity are stepped increase by 5%, the main steam temperature changes by 10.2 ℃, –28.5 ℃, and 35.7 ℃, respectively. In the process of adjusting the water-fuel ratio of the boiler, different times of change in feedwater and fuel flow can have different effects on the main steam temperature. The maximum deviation of the main steam temperature during the transient process reduces by 27.4 ℃ when the feedwater flow is delayed by approximately 100 s compared with the fuel flow. When the load change amplitude is the same, the larger the load change rate, the more severe the fluctuation of the main steam parameters, and the longer it takes to stabilize.

In order to compare the particle formation characteristics of typical high-alkali and high-chlorine Xinjiang coal under combustion conditions, a three-stage high temperature drop tube furnace was used to carry out the combustion experiment of Zhundong coal (ZD) and Shaerhu coal (SEH) in air atmosphere. The characteristics of particulate matter after combustion were analyzed. Particulate matters were collected by Dekati low pressure impactor+ (DLPI+) and the mass-based particle size distribution, elemental compositions and morphology were discussed. The results showed that the particulate matter produced by the combustion of the two coal samples presents a double-peaked model. The fine particle yield of SEH is significantly higher than that of ZD. The main components of sub-micron particles were Na and Cl. The Cl in PM₁₀ accounts for 11.8% and 28.9% of the Cl content in ZD and SEH raw coal, and Na accounts for 2.66% and 7.53% of the Na content in ZD and SEH coal ash. High levels of alkali metals and Cl promoted the formation of fine particles. A large amount of Cl in SEH raw coal migrated into particles and contributed greatly to the formation of sub-micron particles.

The effects of tray parameters on desulfurization efficiency and energy consumption of desulfurization towers are investigated. Through the large-scale hot test platform, the effects of different pore diameters, opening ratio, opening form, weir plate height and different installation positions on desulphurization efficiency and energy consumption are studied. In this paper, the energy consumption efficiency ratio is proposed for the first time as an index to evaluate the operation economy of desulfurization tower. It is found that, under the conditions of experimental platform, when the liquid-gas ratio is not more than 13.6 L/m³, it is economically advantageous to choose sieve plate with medium aperture, high weir board, small opening rate, low-level arrangement, and new aperture design. When the liquid-gas ratio is large than 13.6 L/m³, it is economically advantageous to choose sieve plate with medium aperture, high weir board, large opening rate, high-level arrangement, and new aperture design. The conclusion is of guiding significance for the design and selection of sieve plates for desulfurization and desulfurization towers.

As the global climate continues to warm, capturing carbon dioxide in the air has become one of the most effective measures to reduce greenhouse gas pollution. Carbon dioxide storage systems not only store carbon dioxide in the air, but also consume excess electricity to fill the shortage of electricity supply during peak periods. As the core equipment of CO₂ storage system, the performance of the compressor directly affects the overall performance of the system. This paper summarizes the application scope and performance characteristics of seven different forms of carbon dioxide compressors and the current status of research at home and abroad. The potential problems that may exist in the application of piston, centrifugal and axial flow compressors in CO₂ energy storage systems are discussed, and corresponding suggestions and improvement ideas are given. The results of the study can provide a reference for the design and optimization of CO₂ compressors in the future.

The CO₂ capture process using ionic liquids (ILs) in the coal-fired power plant is simulated, in which the physical properties of ILs and ILs-CO₂ phase equilibria are modelled based on experimental data. Analysis shows that the increase of packed height and absorption pressure is beneficial for CO₂ absorption, while the inlet temperature has the dual effect as it influences both the ILs viscosity and CO₂ solubility. The optimum condition is determined with 20 m packed height, 4 MPa absorption pressure and 50 ℃ inlet temperature. The regeneration process is more energy efficient with pressure swing method, in which the pressure of ILs-CO₂ stream is reduced to 0.1 MPa with almost no ILs loss. Energy consumption and cost analysis shows that the multistage compressor is the most energy-intensive unit, and the absorption pressure has the largest effect on the system with 4 MPa the optimum parameter. With the optimum condition, the energy consumption of the process is 2.21 GJ/t, which is more energy-efficient than the conventional carbon capture system using monoethanolamine.

For the analysis of the heat applied to equipment outside the system boundary, the energy utilized was outside the GB/T 10184 standard, and the boiler efficiency calculation could not take advantage of the existing standard. The external heat loss of hot air was divided into two categories: hot air reuse and hot air non-reuse. Based on the GB/T 10184 calculation framework, the calculation methods of these two categories of external heat loss of hot air were proposed. Taking a 350 MW boiler as a practical example, under the same load, continuous operation of hot air external use and shutdown of hot air external use were compared. According to the actual test data and analysis results, the calculation method was used to compare the actual operating conditions. The influence of external loss of hot air on boiler efficiency was analyzed. The results showed that the test results of combustible materials in two working conditions were basically the same. The external loss of hot air in T01 (cold air recovery) was 0.82%, the external loss of hot air (cold air nonrecovery) was 0.13%, and the external loss of hot air in T02 was 0. The measured boiler efficiency in T01 and T02 conditions was 93.10% and 94.00% respectively. The operation of external hot air system reduced the boiler efficiency by about 0.9 percentage point.

Under the strategic goal of “carbon peaking and carbon neutrality”, the penetration rate of new energy sources is increasing, and coal power is gradually transforming into a flexibly adjustable power supply. While the flexible operation of coal-fired generating units will lead to energy efficiency losses and additional pollutant emissions, which have a certain degree of impact on the cost of power generation and are not conducive to the further exploitation of coal power flexibility resources. In this paper, a method for grading the flexible operating performance of coal-fired units is constructed. By calculating the performance indicators to assess the flexibility performance of coal-fired units under specific operating conditions, the relationship between the unit coal consumption rate and the generation of some air pollutants that affect the cost of power generation and the operational flexibility is investigated. Meanwhile, the kilowatt-hour cost of coal-fired power plants at the second level is estimated. Finally, second-scale operating data collected from a 330 MW unit are used to evaluate the impact of coal-fired unit flexibility on the cost of electricity generation, and build least squares support vector machine (LSSVM) model to realize the prediction of unit power cost under different flexibility levels. The research results indicate that prediction error in specific conditions can be reduced by 50% compared with that in full conditions.

The photovoltaic array will produce multi-peak P-U characteristics under partial shading conditions. Aiming at the problem of how to quickly and accurately realize maximum power point tracking (MPPT) to avoid a large amount of energy loss, this paper proposes an improved aquila optimization (AO) algorithm, which uses Circle chaotic mapping and reverse learning strategy to reasonably allocate the initial population position, so as to shorten the optimization time of the algorithm. At the same time, spiral optimization is carried out for the short gliding attack in aquila optimization algorithm. The whale optimization algorithm is combined to improve local optimal stagnation and convergence speed. Simulations and experiments demonstrate that, in comparison to particle swarm optimization (PSO), whale optimization algorithm (WAO) and aquila optimization algorithm, the algorithm can search the global maximum power point with greater speed, accuracy and suppleness under both static and dynamic partial shading conditions.

In order to improve thermal efficiency of the solar cavity particle receiver, this paper designs the quartz spiral tube solar cavity particle receiver with quartz spiral tube, and establishes flow model to conduct comparative analysis on the structural parameters of the receiver. Finally, the cone angle of the cavity is set to 5°, the number of spiral turns is set to 5, and quartz window is adopted. In order to analyze the heat transfer characteristics of this receiver, this paper studied the influence of different incident radiation intensities and particle mass flow on it. The results show that, within the range of incident radiation intensity of 100 000 W/m² to 350 000 W/m² and particle mass flow of 0.002 kg/s to 0.051 kg/s, the highest particle temperature at the outlet is 672 ℃, and the highest efficiency of the receiver is 70.12%. The research has reference significance for the design of high-temperature solar particle receivers.

In order to understand the performance changes and potential risks of hydrogen assisted combustion in combustion chamber of a lean-combustion premixed gas turbine, a numerical simulation study of the hydrogen injection combustion process of natural gas was carried out in the combustion chamber of Siemens SGT-800 gas turbine. The fuel ignition, temperature distribution, flame formation and NO_x emission characteristics of the combustion chamber under five working conditions of 0, 5%, 10%, 15% and 30% were investigated. Studies have shown that hydrogen-doped combustion in the current combustion chamber will lead to an earlier ignition position of the fuel, an increase in temperature peaks, a shorter axial length of the flame, and a gradual convergence of the outer duty flame towards the central mixer. The temperature distribution and flame morphology in the combustion chamber will not change significantly when the hydrogen-doped ratio is below 15%, but the ignition position in the mixer tube is seriously retracted at 30% hydrogen-doped ratio, and the flame on the outside is close to the nozzle outlet, which has a risk of tempering. In addition, the NO_x emission value of the combustion chamber outlet increases with the hydrogen doping ratio, and the NO_x emission value exceeds the standard by nearly 1/3 at 30% hydrogen doping ratio, indicating that high NO_x emission is also one of the factors restricting the high proportion of hydrogen doping in gas turbines.