The blockage and burst failure of steam tubes caused by exfoliated oxide scales is the major risk faced by supercritical boiler in thermal power generations. With the development of advanced ultra-supercritical thermal power technology, especially, more severe oxidation scale problems will carry over into the higher steam parameters thermal power plants. High temperature coating technology shows a new research methods and approaches in solving exfoliated oxide scale problems. It can not only satisfy the performance requirements of heat resistant steel to high temperature steam oxidation resistant in harsh service environment, but also release the temperature limit of currently used heat-resistant steels due to its inadequate oxidation resistance, which has great application potential in the energy sector. The R&D plans of steam oxidation resistant coatings for steam flow parts of ultra-supercritical thermal power units in the EU, the United States and China are briefly described. The current research progress in preparation and service performance of these coatings is emphatically introduced. The basic research and engineering application issues restricting the large-scale application of aluminide coatings in thermal power units are proposed. And the application prospect of high temperature aluminide coating technology for complex heat-resistant steel tubes of ultra-supercritical power plant boiler is prospected.

Taking a million kilowatt nuclear power half speed steam turbine generator set as the research object, a dynamic model of spring foundation bearing rotor is established by using the rotor dynamics professional analysis software ARMD. The dynamic characteristics of the shafting are obtained through dynamic calculation and analysis. The accuracy of the calculation model is verified by the coincidence of the field measured critical speed of the shafting and the calculated value. On this basis, the vibration response caused by the thermal imbalance of the seal pad of the generator is calculated. It is found that the vibration changes are mainly concentrated at the rotor of the generator, and the thermal imbalance of the seal pad is only the direct influence factor of the vibration fluctuation of the shaft system, but not the root cause. At the same time, the oil film stress of the seal pad under different operating conditions is analyzed, and it is found that the axial inclination has the greatest impact on the stress of the seal pad. Therefore, the processing and installation process shall be ensured during the maintenance and adjustment of the unit to prevent the shaft system deflection during the operation of the seal pad.

The recompression carbon dioxide Brayton cycle has the advantages of simple structure and high cycle efficiency. However, the recompression cycle faces the problems of large boiler pressure drop, high cooling wall temperature and difficult waste heat utilization when applied to coal-fired power plants. The partial cooling carbon dioxide cycle can effectively alleviate the above problems when integrated with coal-fired boilers by virtue of its own circulation characteristics. A thermal calculation program for a 600 MW coal-fired power generation system with partial cooling carbon dioxide cycle is written using MATLAB. Firstly, the effect of single parameter variation on the thermodynamic performance of the system is investigated. The results show that the system efficiency is highest when the main compressor inlet pressure and temperature are near the critical point; the system efficiency drops suddenly when the pre-compressor works near the critical point; the system efficiency is highest when the split ratio and reheat pressure are 0.35 and 17 MPa, respectively. The particle swarm optimization is applied to the partial cooling cycle, and the results show that the partial cooling cycle can achieve the efficiency close to that of the recompression cycle under the suitable design parameters. Compared with the recompression cycle, the mass flow rate of the partial cooling cycle decreased by 17.46% and the boiler inlet temperature decreased from 462.45 ℃ to 429.39 ℃.

The supercritical carbon dioxide (S-CO₂) cycle power generation technology has become an epoch-making and revolutionary frontier technology in the field of thermal power generation because of its own technical advantages. Due to the very harsh working environment, S-CO₂ is easy to cause corrosion problems of equipment materials. In order to ensure the safe and effective operation of S-CO₂ system, the range of working medium parameters and candidate materials of the system’s key equipment are introduced. The current research status of corrosion behavior of metal materials in S-CO₂ environment are then reviewed. The corrosion mechanism in S-CO₂ carbon environment is elaborated in detail. The influences of temperature, pressure, impurities, flow rate and material composition on S-CO₂ corrosion process are summarized. Meanwhile, the research progress of S-CO₂ corrosion prevention and control technology is introduced. Finally, the shortcomings of existing research and the main direction of future research wereare summarized, so as to provide scientific basis for the safe operation of S-CO₂ recycling system in China.

In order to reduce the cost of fuel procurement, a power plant plans to burn economical coal with low calorific value, such as carbon 3500 and Shenhun 4500.The quality characteristics of the coal to be blended deviate from the coal currently used, which affects the safety, economy and environmental protection of the boiler operation.Through coal quality analysis, laboratory test, theoretical analysis and calculation, on-site pulverizing system optimization test, economic coal blending test and operation parameter optimization test, the technology of economic coal blending combustion of boiler is studiedsystematically .The research results show that the low grindability and serious wear characteristics of the carbon 3500 lead to its poor adaptability to the pulverizing system and the boiler, and the comprehensive power supply cost of the unit increases after blending combustion.The fuel characteristics of Shenhun 4500 are close to the main coal types of the power plant, the operation performance of large proportion of mixed burning boilers is good, the comprehensive power supply cost of the unit is reduced, and the economic benefits are significant.It is suggested that the power plant can determine Shenhun 4500 as an economic coal for long-term combustion.This study can provide reference for power plants with similar demand for mixed combustion.

Aiming at the problems of pollution and high carbon emissions caused by island dependence on diesel energy supply, an islanded integrated energy system multi-objective planning optimization method considering carbon emission was proposed. Based on the construction of equipment model, the annual operation of the system was simulated hourly considering the influence of the climate fluctuation on the output of renewable energy devices, the life cycle costs and life cycle carbon dioxide emissions was taken as the optimization objectives, the multi-objective planning optimization model of islanded integrated energy system was constructed by combining with non-dominated sorting genetic algorithm II, the weighted arithmetic averaging operator was used to make decisions on the optimization results. An island area in Yantai was taken as an example, the influence of typical day and annual hourly data as input on planning results, the influence of investment changes in renewable energy devices and natural gas prices, as as well as wind power and photovoltaic installed capacity and battery capacity on optimization objectives were analyzed. By multi-objective planning optimization of the study area, the optimal capacity of each device under different target weights was obtained. The results showed that the configuration of renewable energy and battery can reduce the life cycle carbon dioxide emissions by 26.95% -55.96%. But when the life cycle carbon dioxide emissions weight was increased from 0.6 to 1, the carbon dioxide emissions were reduced by increasing the battery capacity. At this time, life cycle costs increased by 210.13% and life cycle carbon dioxide emissions only decreased by 8.59%. The proposed island integrated energy system planning method provides a reference for decision makers to balance low carbon cost and energy supply economy when planning islanded low carbon IES.

According to GB/T10184—2015, the calculation model of blast furnace gas boiler efficiency is constructed, and the calculation method of blast furnace gas boiler efficiency is analyzed. The results show that the calculation methods of gas moisture content and low-level calorific value are different due to the difference of gas benchmarks.Three methods for solving the excess air coefficient, actual flue gas volume and CO₂ content in the flue gas are proposed for blast furnace gas boilers, and a correction method for exhaust gas temperature of blast furnace gas boilers with gas heaters is proposed;The calculation of some formulas in the GB/T10184—2015 needs to be further discussed, and appropriate modifications can be made.

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.

In order to monitor the condition of the heat recovery steam generator (HRSG) and to ensure the healthy operation of the HRSG, the three-pressure main steam temperature and pressure prediction model was established by using the data from the healthy operation of HRSG and combining the three methods of principle component analysis (PCA), sparrow search algorithm (SSA) and long short-term memory (LSTM). PCA was used to reduce the input parameters of the model from 22 to 9 dimensions, and taking the reheat steam temperature prediction model as an example, it was concluded that the model with PCA dimensionality reduction reduced the hyperparameter optimization time by 11.3% compared with the model without PCA dimensionality reduction. Compared with the model without SSA, the value of coefficients of determination of these models is significantly improved, mean absolute error and root mean square error are significantly reduced, and the alarm threshold of the main steam temperature HRSG is determined according to the distribution of absolute error. Therefore, the condition monitoring model of HRSG based on PCA-SSA-LSTM has short training time and high prediction accuracy, and the model provides theoretical basis and technical support for fault monitoring and diagnosis of HRSG in gas turbine combined cycle power plants.

In recent years, thermal power units have frequently participated in peak shaving to build a new type of power system with new energy as the theme. Accidents of pipeline weld cracking and failure often occur. The welds on both sides of the intersection between the pipeline behind the intermediate pressure bypass valve and the condenser casing frequently crack. The opening area of the muffler pipeline also frequently crack. The heat transfer process from the pipeline behind the medium pressure bypass valve to the condenser muffler is studied by using the finite element method，The distribution of thermal stress under normal and peak shaving conditions was compared. To investigate the causes of the problem, a comprehensive calculation model for the medium pressure bypass pipeline is first established to obtain the distribution of primary and secondary stresses in the pipeline under normal working conditions, as well as the displacement and bearing values of each node. The finite element method is used to study the heat conduction process from the local medium pressure bypass valve to the condenser silencer pipeline. The thermal stress distribution under normal and peak shaving conditions is studied. The results indicate that under peak shaving conditions, the poor atomization effect of the nozzle results in severe water entrainment in the steam, The temperature difference between the pipeline behind the bypass valve and the pipeline of the condenser muffler is larger and repeated operation and shutdown of the desuper heating water cause thermal fatigue fracture of the weld seam and the opening area.