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.

It is necessary to break the technical barrier and make breakthroughs in information system, control system, device and other aspects when reforming large thermal power excitation system domestically. The article first systematically concludes and summarizes the key technologies of modern excitation technology, including control and command subsystems, communication subsystems, rectifier subsystems, and excitation subsystems. It analyzes and summarizes the research status, existing problems, and difficulties involved in each technology at home and abroad. Secondly, the localization and replacement process of the HN-i6200 excitation system for large-scale supercritical 670 MW thermal power units was described. Targeted design was carried out to meet the special requirements of the excitation system operation for thermal power units, and highly reliable domestic DC breakers were developed. Through experimental research, the operation strategy of the excitation system for thermal power units was overcome, and a nationally produced HN-i6200 excitation system was successfully developed. The on-site testing and system modeling have verified the working performance of the nationwide production excitation system, providing technical and practical references for the localization of excitation technology in the power industry.

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.

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.

A regional integrated energy system based on solar, geothermal and natural gas is constructed to meet the multi-load demands of buildings, electric vehicles and hydrogen fuel vehicles. Hydrogen storage tank and heat storage tank are used to adjust the system flexibility, and to achieve systematic low-carbon economic operation on the basis of meeting the energy demand. Taking the residential community as an example, the distinctions of travel behavior for new energy vehicles on weekday and weekend are investigated, the change of travel frequency with different seasons are also considered, and the yearly loads of residential and new energy vehicles are determined. Primary energy saving rate, CO₂ emission reduction ratio and total annual expenditure reduction ratio of the proposed system are set as optimization objectives, and the capacity configuration of integrated system is optimized based on the mixed integer linear programming so as to evaluate the system performances from the aspects of economy, energy and environment. The results show that, primary energy saving rate, CO₂ emission reduction ratio, total annual expenditure reduction ratio and total investment income of the optimized system are 42.95%, 55.89%, 50.82% and 49.18%. In the integrated system, the input power of public grid only accounts for 16.93% of the total power load. This study provides theoretical basis for the integration of novel energy supply system considering coupling loads of residential building and new energy vehicles, which is helpful to promote the application of integrated energy system in building and transportation areas.

In response to the instability problem of distributed new energy as an independent power source supplying energy to household energy systems, a capacity configuration method for distributed home energy systems based on hydrogen energy is proposed. This method is based on the characteristics of hydrogen energy that can suppress wind and solar fluctuations and flexibly convert load demands, and constructs a hydrogen coupled distributed energy family terminal energy system structure. Combining with the characteristics of renewable resources in the region, a hydrogen based distributed household energy system capacity allocation model is established with the goal of minimizing the net total cost. Taking the wind and solar resources and typical household energy data in Xinjiang region as an example, the impact of the configuration capacity of distributed energy and hydrogen energy systems on the system is simulated and analyzed, and the optimal capacity configuration of hydrogen energy systems under the optimal wind and solar ratio conditions is obtained. From the simulation results, it can be seen that the proposed model can effectively reduce the total cost of the household energy system while achieving reliable energy supply off the grid, and promote the consumption of new energy, which provides suggestions for the design of distributed household energy based on hydrogen energy.

The dynamic characteristics of the bottoming cycle of a gas turbine combined cycle have a significant influence on the load variation characteristics of the unit. Partially recuperation is a new method which can be used to improve the performance of combined cycle at partial load, it is an important part of system feasibility evaluation to study the effect of partially recuperation on the dynamic characteristics of the bottoming cycle. In this paper, a dynamic simulation model of the bottoming cycle system of a partially recuperative combined cycle unit is established by using modular modeling method, and the dynamic characteristics of inlet parameter disturbance and load shedding process are studied. The results show that, the dynamic model can accurately reflect the dynamic characteristics of the bottoming cycle, and the simulation results show that the dynamic response of partially recuperative units facing the disturbance of exhaust parameters is consistent with that of conventional units. The disturbance of exhaust temperature T₄ mainly affects the high-pressure superheated steam and reheated steam, and the influence range is larger. The disturbance of T₄ with 5% can reduce the bottoming cycle power by 16.32%. The response speed of the unit is slower, and the time constant of the steam turbine power is about 400. The disturbance of exhaust flow affects the steam of each stage, and the influence range is relatively small, the disturbance of 10% reduces the bottoming cycle power by 9.49%, the response speed of the unit is faster, the time constant of the steam turbine power is about 60. When the recuperative ratio is disturbed, the dynamic response of the unit is similar to that of the T₄ disturbance, and the operation strategy of recuperative regulation results in the load variation of the combined cycle being borne entirely by the bottoming cycle, the time needed for partially recuperative units to reach steady state is 1 100 s later than that of conventional units, and the recuperative regulation mode is suitable for use in the load interval below 51.4%.

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.

A Python model was established for thermal performance of the heavy-duty gas-steam combined cycle triple-pressure heat recovery steam generator. The model calculates the detailed heat recovery steam generator parameters under the condition of changing unit load, including main steam pressure and flow rate, heat and heat transfer coefficient of each heat exchanger, as well as power output and efficiency. As the effect of exhaust gas temperature and flow rate on the heat recovery steam generator is analyzed, how the ambient temperature, humidity and fuel heating affect the heat recovery steam generator output is also discussed when the unit is in part-load. It is verified that the model has good simulation accuracy and calculation efficiency. Simulations for one certain frame gas turbine combined cycle show that: When the unit load is reduced from full load 650 MW to partial load 250 MW, the triple main steam pressure and feed water flow rate of heat recovery steam generator decrease, the steam turbine power output decreases from 219.1 MW to 130.4 MW, and the efficiency of heat recovery steam generator increases from 89.3% to 92.1%; main-steam flow increases as the flue gas flow rate and temperature increase at the inlet of heat recovery steam generator; As the load of the random group decreases, the heat transfer coefficient and heat transfer amount of each heat exchange surface of the waste heat boiler decreases, but the proportion of heat exchanger between the flue gas and the high-temperature section heat exchanger in the total heat increases, and the heat transfer between the flue gas and the low-temperature section increases. The proportion of heat exchanger heat transfer in the total heat is reduced; when the unit load is reduced from 650 MW to 300 MW, the proportion of steam turbine shaft power increases by 1.67 percentage points, the proportion of heat loss in the chimney flue gas decreases by 2.63 percentage points.

Under partial shading conditions (PSC), the P-U characteristics of a solar photovoltaic array may exhibit multi-peak phenomena. Conventional algorithms tend to fall into local maximum power point (LMPP), while maximum power point tracking (MPPT) methods based on meta heuristic algorithms are difficult to balance speed and accuracy. In this regard, this paper designs a hybrid algorithm based on the improved particle swarm optimization (IPSO) with embedded the improved perturbation and observation (IP&O). The velocity and position of the particle are first updated by the IPSO algorithm. Then, perform MPPT based on the position of particles using the IP&O algorithm. The tracked power is used as the fitness value of the particles, so that IPSO can find the global maximum power point (GMPP) among many LMPPs. Finally, with the global optimal output of IPSO as the initial position, IP&O is used again for global maximum power point tracking (GMPPT). Comparing the proposed algorithm with IP&O, IPSO, and IPSO-P&O through simulation, the simulation results show that the proposed algorithm performs excellently in tracking speed and accuracy, especially in the case of a wide voltage search range, and has smaller power oscillations during the tracking process.

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.

To establish an accurate and effective dynamic model of cogeneration units, a modeling method based on digital twin technology is proposed using unit operation data. Firstly, the historical data stored in the unit data server is extracted, it is then clustered using the improved genetic simulated annealing fuzzy C-means method to establish a historical data clustering library. Then, during the operation of the unit, real-time operational data is collected and transmitted, and a multi-level similarity recognition strategy is used to retrieve the historical data closest to real-time operational data in the historical data clustering library. Then, based on the optimization, the extreme learning machine will use the searched historical data for unit modeling. Finally, a twin model of a cogeneration unit in Hangzhou is established and comparative experiments are conducted. The results show that, the built model meets the accuracy requirements and can track the real-time state response of the unit. The model accuracy can be further optimized by flexibly changing the parameter settings during the modeling process.

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.

In order to explore the formation and evolution of soot during the combustion of coal, this paper uses Pingdingshan coal as combustion material, and uses the light scattering method coupled with the thermophoretic sampling article diagnostic method to measure the soot mass in flame. A light scattering measurement system capable of precise vertical movement is constructed to measure the light scattering intensity at different heights of the flame. The particle size distribution is obtained by the thermophoretic sampling particle diagnostic method, and the soot mass at different heights when the flame is calculated by Mie scattering theory. The results show that as the flame rises, the median mass diameter of soot firstly increases and then decreases. When the flame burns stably, a large amount of soot is formed at a height of H=10 mm. As the flame rises, the mass of soot decreases rapidly in the H=10~30 mm range. In the range of 10~20 mm, the soot mass of Pingdingshan coal decreases by 58.62%. When H>40 mm, the soot mass of Pingdingshan coal slowly decreases.

The typical faults of wind turbines are summarized. The fault data and non-fault data of converter system, generator system, variable propeller system and auxiliary power system with high fault frequency of wind turbines in a wind farm are selected for fault diagnosis research. The fault diagnosis model is established by ELM, SVM, KELM and WOA-KELM algorithms respectively. At the same time, Laplacian scores are used to sort and select the importance degree of model characteristic variables. WOA-KELM algorithm achieves better diagnostic effect by optimizing the regularization parameter C and kernel parameter γof KELM algorithm. The results show that, the diagnostic accuracy of the four algorithms for non-fault types is 100% under different sample numbers. The average diagnostic accuracy of WOA-KELM algorithm improves from 88.0% to 93.2% after feature screening by using Laplace scores. In the range of 250~500 samples, the diagnostic accuracy of WOA-KELM algorithm reaches the maximum of 96.0% after feature screening. It is proved that this model can effectively realize the fault diagnosis of wind turbine, and provide guidance and reference for field operation and maintenance personnel.

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.

To solve the problem of excessive air leakage from the four-compartment air preheater, a four-compartment rotary air preheater of a 1 000 MW power plant is used as the study object to investigate the thermal characteristics, rotor thermal deformation and air leakage of the air preheater, by combining theoretical analysis with numerical simulation. The numerical simulation results show that, for every 1% increase in air leakage rate of the 1 000 MW unit, the heat transfer efficiency of air preheater will be reduced by 1.13%, and the power plant will consume 3 604 tons of standard coal more on average per year. There are large temperature gradients in the axial and circumferential directions inside the air preheater, and most of the corrosion and deposition areas are distributed in the low temperature section. There are large differences in rotor thermal deformation during different operating conditions of the air preheater, and the maximum thermal deformation occurs on the secondary air side. It is necessary to make corresponding adjustments according to the thermal deformation characteristics of different positions of the rotor when setting the sealing system.

Creep rupture is one of the most common failure modes of pipelines used in thermal power plants. Residual life prediction is an effective guarantee to ensure the safety, utilization and benefit maximization of equipment. Based on the creep rupture test data of 2.25Cr-lMo heat-resistant steel in actual service for over 200 000 hours, the selection principle of TTP parameters and its influence on the accuracy of life prediction are analyzed by comprehensively considering the working stress and TTP parameters. The relationship curve family of Z-parameter method is used to characterize the vertical dispersion of pipeline durability data in different power plants. The stress-TTP-reliability curve for evaluating the reliability of life prediction is established, and the relationship between the predicted life of different power plant pipelines and the working state of the unit is obtained. The creep residual life of different power plant samples at 540 ℃/45.26 MPa is 1.725 6×10⁵ h and 3.378 8×10⁵ h respectively, and the predicted reliability reaches 99%, which provide maintenance suggestions for the operation reliability of power plant equipment.

For the purpose of absorbing renewable energy, the coal-fired power units are required to operate flexibly, and the resulting variable operating environment will lead to large nonlinearity and uncertainties of the wet desulphurization process. Particularly, the time delay will make the control even harder. Therefore, in order to achieve a more flexible control structure, a new desulphurization control strategy based on frequency retrofit is proposed. Based on the strategy, a dynamic model is obtained through field experiments. Meanwhile, in order to deal with uncertainty well and achieve safe compensation of uncertainty in the control process, an updated Gaussian process model predictive control method for time-delayed objects is proposed, and the performance of the method is demonstrated by parameter analysis and simulation experiments. Finally, the effectiveness of the proposed control strategy and control method is verified by field application.

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.

The fault early warning of the coal mill is of great significance to the safe operation of thermal power unit, but the operation of the coal mill has many interference noises and a high degree of coupling, which makes the fault early warning more difficult. Based on this, this paper proposes a fault warning method based on wavelet packet transform (WPT) and Transformer. Firstly, the signal is denoised by the wavelet packet analysis method with adaptive threshold value. Then, the characteristic parameters related to the fault measurement point are selected as input to establish a Transformer coal pulverized prediction model based on the self-attention mechanism. Finally, the kernel density estimation method is used to analyze the prediction deviation and determine the warning threshold. Taking a 660 MW medium-speed coal mill as the research object and using actual data for verification, the experimental results show that the prediction accuracy of the proposed method is higher than that of CNN, LSTM, and CNN+LSTM models, and it can provide early warning of coal mill failures.

The long-term vibration of ZGM133G-I type medium speed coal pulverizers in a power plant causes weld fatigue fracture of the powder delivery pipeline, which results in coal powder leakage, polluting the environment and seriously affecting the operation of the unit. Based on the mechanical vibration analysis and field test of medium-speed coal pulverizers, this paper studies the influence of operating parameters such as loading force, speed of separator and output of coal pulverizers on the vibration of coal pulverizers. The results show that, the vibration of medium-speed coal pulverizers is mainly caused by the mechanical equipment itself and the setting of operating parameters. The size and separator type of coal pulverizers are not the inevitable factors that cause the vibration of coal pulverizers, but the wear and damage of mechanical structure will cause the vibration of coal pulverizers. In order to reduce the vibration of medium-speed coal pulverizers, it is necessary to comprehensively consider the output of coal pulverizers and the fineness of coal powder according to the test results, and reasonably control the loading force, separator speed and output.