H₂S is an important product produced by power plant boilers in the process of low NO_x combustion. To solve the problems that H₂S may cause various hazards to thermal power plants due to its inflammability, strong corrosion and extreme toxicity, tunable diode laser absorption spectroscopy (TDLAS) method combined with multi-pass cell and computer is employed to build an online measurement system for detecting the molar fraction of low-concentration gas. By using this measurement system, accurate online measurement of H₂S in the mixed gas with the molar fraction of 10^–6 magnitude is realized, and the H₂S high-temperature reaction experiment is carried out to explore the influence of experimental temperature and the molar fraction of O₂ in the mixed gas on the reaction. The experimental results show that, under the conditions of pressure of 80 kPa and molar fraction of O₂ ranging from 0 to 5%, the temperature at which H₂S begins to react changes with the molar fraction of O₂. On the whole, the higher the molar fraction of O₂ in the mixed gas, the lower the temperature at which H₂S begins to react. The experimental results can provide some data basis for the generation, transformation and harm control of H₂S in boiler flue gas.

An improved grey wolf optimizer (MGWO) is used to optimize BiLSTM to predict water wall temperature. The improved algorithm adopts nonlinear factor adjustment strategy, adaptive position update strategy and dynamic weight modification strategy to improve the global optimization ability of the GWO. The improved grey wolf optimizer is used to optimize the number of hidden layers, learning rate and regularization parameters of the BiLSTM model to improve the prediction accuracy of the model. The data of a power plant in Xinjiang are used for prediction simulation. The results show that, the improved optimizer has higher prediction accuracy, and can predict the change trend of wall temperature when the unit is lifting and lowering load. Compared with the LSTM and BiLSTM models, the average root mean square error of the model reduces by 9.86% and 3.69%, respectively, and the overtemperature of water wall temperature can be predicted in advance, which is of great significance for the prevention of overtemperature of water wall.

In order to solve the problems of high error and low classification accuracy in the fault diagnosis process of wind turbines caused by the high dimension, feature redundancy and feature correlation of wind turbine supervisory control and data acquisition (SCADA) data, a three-stage feature selection method based on LightGBM-VIF-MIC-SFS is proposed. Firstly, based on the importance calculation of all features implemented by LightGBM, a preliminary feature space is determined. Secondly, a correlation discriminant matrix is constructed based on the variance inflation factor (VIF) and maximum information coefficient (MIC) to evaluate features with similar importance in a single screening, and discard input features with high similarity. Finally, the sequential forward search method is used to process the features for the third time, input the features obtained from the previous two feature selection one by one, and retain the features that can improve the system performance, so as to achieve the final feature selection. After the establishment of the model, the real SCADA data of the wind farm is used for performance evaluation, and the proposed algorithm is compared with the two comparison algorithms on six data sets. The results show that LightGBM-VIF-MIC-SFS has significant advantages over the two comparison feature selection algorithms. A ablation experiment was conducted on the three modules within the proposed algorithm, effectively verifying the effectiveness of each module within the proposed feature selection method and the rationality and accuracy of the optimal feature space obtained based on the proposed method.

Xinjiang high-alkali coal is a cost-effective power coal，but when it is used in large proportions, boiler equipment is prone to severe slagging problems. The design principles of the combustion system for boilers using Zhundong coal are inconsistent with conventional technical measures to improve low-load stable combustion performance. To solve this problem, based on the mechanism of stable combustion of pulverized coal, measures such as optimized layout of tiny oil ignition burners, interlaced arrangement of middle layer burners, online adjustable coal powder concentration and burner design optimization have been studied. The technology was applied in a 350 MW unit's deep peak regulation retrofit project using Zhundong high-alkali coal as fuel, and achieved a stable combustion load of less than 18% rated condition without oil injection.

Thermal power units are faced with a variety of ways to sell electric heating products, such as electricity contract market, spot market electricity sales, auxiliary service market electricity sales, civil heating and industrial heating. It is necessary to optimize the distribution of limited thermal power unit electric heating products in various markets according to the market trading mechanism, operating costs and carbon emission cost to obtain maximum profits. The intelligent decision-making system can help thermal power units to provide the optimal group and bidding strategy at all levels of the market, business accounting and the optimal operation mode of units.

In order to further investigate the loss mechanism in supercritical carbon dioxide turbines, the flow characteristics in a turbine stage were studied by numerical method. The losses in the passage of stator and rotor blades were decomposed, and the various loss values and their proportions were quantitatively calculated. The loss sequence of the supercritical carbon dioxide turbine stage was clarified. The results show that, the high density of supercritical carbon dioxide and low blade height result in a very large leakage loss in turbine stage. When the stage load coefficient is 0.93, the relative height of the stator clearance is 0.012 and the relative height of the rotor clearance is 0.010, the leakage loss accounts for 38.23% of the total loss, including 21.94% of the diaphragm seal leakage loss and 16.29% of the tip seal leakage loss. Except for leakage loss, when the average maximum thickness divided by chord length is 0.33 and the aspect ratio is 2.07 in stator passage, the profile loss is much higher than the endwall loss and trailing edge loss, accounting for 9.68% of the total loss. In rotor passage, when the average maximum thickness divided by chord length is 0.28 and the aspect ratio is 1.73, the difference among endwall loss, profile loss, and trailing edge loss is not significant, and the profile loss has the highest proportion, accounting for 15.39% of the total loss. The influence range of secondary flow in rotor is even wider, and its endwall loss is much higher than that of the stator. The main sources of endwall loss are viscous dissipation of fluid near the end wall and secondary loss caused by horseshoe vortices, passage vortices, etc. The research results will provide direction guidance and data support for the design and optimization of supercritical carbon dioxide turbines.

In order to study release characteristics of sodium during thermal conversion of high-alkali coals, the release characteristics of sodium in high-sodium coal and low-sodium coal were compared and analyzed through combustion experiments and pyrolysis experiments of raw coal and water-washed coal, so as to explore the release law changes of different forms of sodium in coal samples during combustion and the influence of atmosphere changes on sodium release. The results show that, during the combustion experiment, the release of sodium from high-alkali coal increases slowly at 300~500 ℃ and rapidly at 500~1 100 ℃, and the release of sodium from low-alkali coal increases rapidly at 300~500 ℃ and slowly at 500~1 100 ℃. It can be seen that, coal quality is one of the main reasons affecting sodium release, and sodium release will be greatly affected by the difference in coal composition. The release law of sodium during combustion and pyrolysis is basically the same, the sodium release rate changes slowly during the pyrolysis process, and is about 7.0% lower than that of the combustion process. The release characteristics of organic sodium and water-soluble sodium are different due to different release routes.

High-alkali coal such as Zhundong coal has huge reserves in Xinjiang, in which rich alkali metal elements can easily lead to fouling and slagging problem on heating surface of the furnace, thus to decrease the safety of boiler. It is of great significance to develop efficient and clean combustion power generation technology for high-alkali coal to achieve the “double-carbon” goal. The research progress of the online monitoring technology in high-alkali coal combustion furnace based on spontaneous emission radiation analysis is summarized. The development trend and dynamics are discussed focusing on the research status and application of emission spectrum technology and spontaneous emission radiation imaging and image processing technology in high-alkali coal combustion monitoring. Emission spectroscopy can obtain the temperature and component concentration by processing the spectral radiation signal emitted by the flame at different wavelengths. Recently, it has been widely used to measure the combustion temperature and the gaseous alkali metal concentration in the industrial furnace and judge the slagging trend in the furnace qualitatively. Different from emission spectroscopy technology, spontaneous emission radiation imaging and image processing technology has the ability to analyze the spatial distribution of signals. The technology obtains the spontaneous radiation image in the furnace via CCD, CMOS and other surface array sensors. Based on image processing technology and thermal radiation imaging theory, the temperature distribution of the combustion field in three-dimensional space can be obtained combining with solving radiation inverse problem, which makes it possible to monitor the three-dimensional visual of slagging formation. In the future, monitoring of the fouling and slagging on the heating surface in two or three dimensions should be carried out based on emission spectroscopy technology, spontaneous emission radiation imaging and image processing technology. Combined with the distribution of parameters such as combustion temperature and gaseous alkali metal concentration in the furnace, a quantitative judgmental index of fouling and slagging on the heating surface of high-alkali coal combustion should be established to achieve the goal of online prediction of fouling and slagging on the heating surface.

China has abundant high-alkali coal resources. This article provides a comprehensive review and summary of the research and engineering application progress of high-alkali coal combustion technology from the aspects of basic research, key technologies, and engineering practice. In particular, the latest status of the mechanism research and practice of fully burning Xinjiang high-alkali coal in a wet-bottom boiler is introduced. The review aims at providing a reference to develop more economic combustion technology that can safely co-fire a high proportion or even solely burn Xinjiang high-alkali coals in a long operational period.

In order to reduce fuel procurement costs and ensure fuel supply, a certain power plant in Gansu burns a large proportion of Xinjiang high-alkali Guanghui coal and Xinjiang Energy coal. After burning the high-alkali coal, the boiler experiences severe high-temperature corrosion and coking on the heating surface, and the maximum load can only be carried to 85% ECR. In order to reduce high-temperature corrosion, research has been conducted on coal quality characteristics, combustion optimization adjustment, and equipment improvement technology for boilers. The research results show that, the boiler still experiences severe high-temperature corrosion even when burning low sulfur coal, which is mainly related to the high content of alkali metals such as sodium and calcium, as well as chlorine in Xinjiang coal. By increasing oxygen content, reducing primary air volume, weakening the swirling strength of outer secondary air of the burner, and increasing wall-attached air, operation adjustment measures can improve the high-temperature corrosion characteristics of the water wall to some extent. But to completely solve this problem, it is necessary to start with the use of additives, high-temperature corrosion prevention spraying, adding soot blowers, improving wall-attached air and burner design, and other corresponding technologies. The results of this study can provide useful reference and guidance for power plants that encounter similar problems during the process of high-alkali coal burning.