Based on a typical recompression Brayton cycle, a thermodynamic model was established for a supercritical carbon dioxide (sCO₂) power generation cycle, and analyses were conducted on the influence of key parameters on the system performance. Through design optimization by applying genetic algorithm, the maximum efficiency of system and corresponding operation parameters were obtained. Results show that, a higher system cycle efficiency can be obtained when the inlet temperature and pressure of main compressor are close to the critical point and the inlet temperature of turbine is higher. With the increase of the pressure ratio of main compressor, the cycle efficiency increases at first and then decreases, while there is an optimal pressure ratio. Research results can serve as a technical reference for the engineering application of sCO₂ power generation technology.

For an ultra-supercritical unit with a back pressure steam turbine for heat supply, researches were conducted on the unit with deep peak regulation under different heat supply modes. Through theoretical calculations, the economic benefits of the back pressure turbine under operational and non-operational modes during deep peak regulation conditions were analysed, while comparisons and analyses were conducted on the economic benefits of the steam from the back pressure turbine for the regenerative heating system and directly for external heat supply. Result show that the comprehensive economic benefit of the back pressure turbine under operational mode in low load is increased by 198 400 yuan per year compared with under non-operational mode. The unit heat rate of the back pressure turbine for the regenerative heating system is improved by 171.83 kJ/(kW·h) under 50% load compared with directly for external heat supply.Under deep peak regulation condition, the method of the back pressure turbine directly for external heat supply can be adopted when the flow rate for heat supply is higher than the minimum flow rate at the back pressure turbine inlet, and the method of the back pressure turbine for the regenerative heating system can be adopted when the flow rate for heat supply is lower than the minimum flow rate at the back pressure turbine inlet. Finally, the flexibility of unit operation can be improved with the back pressure turbine put into operation under deep peak regulation condition.

To optimize the operation strategy of combined heat and power unit under different deep peak regulation conditions and electricity price periods, methods such as mathematical modelling, deep coupling, and intelligent optimization were adopted for research. The study found that during single unit operation, when the peak regulation assessment price is higher, the heat-supply amount can be appropriately increased, so as to balance profits and avoid negative profit situations at certain nodes. Profits vary significantly under different peak regulation periods: the profit of low load operation is prior to that of high load operation during heat-supply period, while the priority dispatch of power generation can obtain higher profits during non heat-supply period. Further researches were conducted on load distribution based on single unit research. Results reveal that, the coal consumption rate of double units operation is higher than that of single unit operation under same operation conditions. However, due to the support from peak regulation compensation policies, the profit of double units operation is much higher than that of single unit operation. Researches on the coupling of electricity price policies show that, the profit can be significantly increased with the high load operation of the unit during peak electricity price period, while the unit should be avoided to operate near peak regulation load nodes during valley electricity price period, so as to prevent serious losses. Research findings can provide a scientific basis for optimizing the dispatch of combined heat and power units.

A new type of drainage device selected for the gland steam condenser in a domestic new-built power generation unit was introduced, detail analyses were conducted on its composition, structure, and working principle, while comparisons were carried out between this device and the traditional gland steam condenser (adopting multistage water sealing). It is concluded that this device has the advantages of simpler equipment operation, stronger adaptability to back pressure, higher safety of the equipment itself and the unit, as well as being beneficial for the operation of air-cooled condenser units and peak regulation units. Based on above researches, a further energy-saving retrofit scheme of "zero leakage" of gland steam condenser was proposed. By optimizing the interface position with changing the installation height of internal pipelines, it is estimated to save an annual cost of 3 600 yuan in desalinated water production for the power plant.

To clarify the actual thermal performance of a 660 MW coal-fired unit under deep peak regulation condition with 30% rated load, thermal performance tests were conducted in accordance with relevant testing standards. The test results show that, the boiler thermal efficiency and steam turbine heat rate of the unit under this condition are 92.81% and 8 529.4 kJ/(kW·h), respectively. The gross coal consumption rate is 317.1 g/(kW·h), which is equivalent to the design value [316.3 g/(kW·h)]. By using a deviation analysis method, it is determined that the main reason for the lower boiler thermal efficiency compared to the design value is the high actual flue gas loss. Although the efficiencies of the high, medium, and low pressure cylinders of the steam turbine have decreased to varying degrees, the overall steam turbine heat rate is still better than the design value due to the actual back pressure of the unit being significantly lower than the design value. Based on the test results, it is inferred that the error of gross coal consumption rate calculated by positive balance method is mainly due to sampling, preparation, and analysis errors of coal and the statistical error of coal consumption measurement device. Compared with the 50% rated load condition, the operation safety of the unit under the deep peak regulation condition is decreased, the auxiliary power rate of the unit is increased by 3.45 percentage points, the boiler thermal efficiency is reduced by 1.72 percentage points, and the steam turbine heat rate is increased by 157.5 kJ/(kW·h). The research results provide a reference for similar units to master the thermal performance under deep peak regulation condition.

Aiming at the variable-diameter and variable-pitch spiral shaft structure in the biomass fuel compression and conveying equipment, a parametric calculation model was established through the analysis of its compression and conveying mechanism. A 14 inches spiral shaft was taken as an example to design the structure, and the compression and conveying process of corn stalk was numerically simulated. Finally, the compression and conveying performance of the spiral shaft was further verified by prototype test. In numerical simulation, the compression ratio of corn stalk reaches 2.408. The experimental results of corn stalk compression and conveying show that the compression and conveying effect of the variable-diameter and variable-pitch spiral shaft structure designed by the parametric calculation model is good, which is in line with the expected standard of corn stalk compression and conveying. The design method using parametric calculation model has certain feasibility and can be extended.

To establish a broadly applicable design framework of fuel flow control method for an F-class gas turbine, researches were conducted on the total fuel flow control design, fuel distribution control loops design, Wobbe index adjustment, and pressure regulation valve design, a general control method of gas turbine fuel flow was formed, and the simulation verification of fuel flow control strategy was completed. Results show that, based on the proposed fuel flow control strategy, the fuel flow control effect of this F-class gas turbine can be realized under all conditions from ignition, warm-up, acceleration, grid-connection, load ramp-up to full load. Research results can serve as a reference for the design and improvement of relevant control algorithms for F-class gas turbine fuel flow, further supporting the efficient, stable, and safe operation of the gas turbine.

By using macroscopic inspection, chemical composition analysis, fracture analysis, metallo-graphic inspection and mechanical property test methods, the fracture position of Inconel 718 alloy valve stem of a supercritical 600 MW unit was analysed. The specific improvement suggestions were given through failure causes analysis. Results show that, the chemical composition, metallographic structure, hardness and impact properties of the valve stem can meet the requirements. The grain structure of the valve stem sample is slightly coarse, with many inclusions and mainly carbides, and the tensile property parameters are lower than the standard value. The reason for the valve stem fracture failure is that the strength of the material is insufficient. Meanwhile, the groove root and screw thread groove on the component are stress concentration points. Under the action of stress, the groove root cracks will be generated and then be expanded, leading to the fracture.

Using the finite element method, a model was established for the persistent leakage phenomenon occurring during load variation at the split-plane end of the high-pressure cylinder in a Russian-made nuclear power steam turbine, the influence of factors such as load level, bolt preload, and external shaft gland insulation on the leakage was significantly researched. Firstly, a finite element model of the high-pressure cylinder end was developed to analyse the impact of load level variations on the steam supply parameters of the shaft glands, and subsequently, the variation rule of the contact pressure at the split-plane end of the high-pressure cylinder under different loads was discussed. Secondly, the influence of bolt preload on the distribution of contact pressure was investigated. Finally, based on research findings, a solution involving external pressurized sealing was proposed, and a simulation body and sealing fixture for the end of the high-pressure cylinder were designed. Results show that bolt preload has a significant local impact on the contact pressure but has a relatively minor direct impact on the leakage area, while the external shaft gland insulation can improve the end contact condition to a certain extent. When the gap between the sealing fixture and the cylinder wall is less than 0.2 mm, the internal pressure within the simulation body of cylinder can be effectively maintained. While field implementation effects can further validate this conclusion.

After switching the heating mode of a steam turbine in a gas-steam combined cycle unit, there was a sudden increase in vibration of the low-pressure rotor of the steam turbine, prompting an emergency switch back to the previous mode. Through the analysis of changes of operation parameters before and after the incident, the preliminary determination of the incident cause was the change in steam admission parameters of the low-pressure cylinder after mode switching. To solve this problem, the set value for the exhaust steam pressure of the intermediate-pressure cylinder was adjusted, and another mode switching test was conducted. During this test, the changes in steam admission parameters of the low-pressure cylinder were reduced, and there was no significant change in vibration after mode switching. This case can serve as a reference for analysing other similar incidents.

The working principle and force analysis of the buckstay corner components for supercritical boiler were mainly introduced, including the design of buckstay corner components for vertical water wall tube and spiral water wall tube, and the requirements for field installation of corner components were described. Results show that, the design of corner components should pay attention to the size and quantity of parts, the length of weld and the height of welding foot, and the size match of pin and pin hole. During the installation of corner components, welding should be performed according to the drawings to avoid missing welding.

According to the leakage fault of high-pressure cylinder of a condensing steam turbine, the change of through-flow parameters during the fault process was analysed, the steam flow rates of different stage groups were calculated by Flugel formula, and the steam leakage was estimated. Additionally, the leakage process was simplified to isentropic expansion process, the irregularity of the leakage point was ignored, the leakage point was equivalent to an ideal nozzle, and the flow rate of the ideal nozzle was calculated. Results show that, the error between the estimation result of Flugel formula and the leakage of the dropped plug is within the allowable range of engineering. The research results provide a novel computational approach for fault calculation in turbine through-flow components, diverging from conventional methods which only use Flugel formula for flow rate estimation. The difference of flow rate of different stage groups is innovatively used to calculate the leakage of through-flow abnormal part. This method provides a functional assistance for fault location and fault component determination.

In order to explore the influence of type Ⅰ and type Ⅱ boundaries in the weld of TP347H/12Cr1MoV dissimilar metal welded joint after high temperature aging treatment on the microstructure and properties of the joint, CALPHAD method was employed, and Thermo-Calc software was utilized to study the equilibrium phase composition and precipitate behavior of the welded joints. The simulation results from Thermo-Calc software indicate that, under the same temperature at 600-800 ℃, the carbon activity in each alloy decreases in the order of 12Cr1MoV, weld, and TP347H. Considering the activity factor, the direction of carbon migration is from 12Cr1MoV to the weld at first and then to TP347H, which is consistent with the actual results of carbon migration. Additionally, the TP347H/12Cr1MoV welded joint was subjected to isothermal aging treatment at 650 ℃ for 1 500 h, then the microstructures and precipitate characteristics of type Ⅰ and type Ⅱ boundaries were analysed using metallographic microstructure observation, scanning electron microscopy, and energy dispersive spectroscopy. Results show that, the weld microstructure consists of a mixture of cellular and dendritic crystals. The solidification mode of the weld in the TP347H/12Cr1MoV welded joint is primarily the austenitic A-type solidification mode. After aging treatment, Cr-rich and Nb-rich phases appear in type Ⅰ and type Ⅱ boundaries of TP347H and weld interface.

A simulation method for the condensate water throttling dynamic process in coal-fired units based on Dymola software was proposed. For a 350 MW supercritical unit, a dynamic simulation of the condensation water throttling process under automatic generation control (AGC) condition was conducted. The dynamic process and primary control and regulation model of the coal-fired unit was developed, and the accuracy of the model was verified. By simulating the impact of the condensate water throttling on the dynamic characteristics of the coal-fired unit, the response rates of the coordinated control system (CCS) lifting and lowering loads of 90% and 75% thermal heat acceptance (THA) conditions were compared with those of the traditional CCS lifting and lowering loads under the condensate water throttling conditions. The simulation results indicate that the CCS involving condensate water throttling can respond quickly to the lifting and lowering load commands, and the load response rate of the unit is significantly higher than that in the traditional coordinated case. Additionally, the condensate water throttling process has minimal effects on the main steam and reheated steam temperature/pressure of the unit.

The deformation of the high-medium pressure inner cylinder of a supercritical 660 MW unit steam turbine under working conditions was analysed and calculated using the finite element method. The radial deformation at different axial positions of the cylinder was obtained, and improvement and optimization measures were proposed. The analysis results show that under steady-state operating conditions, the radial deformation of the cylinder exhibits a vertical elliptical shape in the middle section and more flattened ellipses at both ends, with higher ellipticity at the ends. After analysing the causes of deformation and adopting improvement measures, the radial deformation ellipticity of the cylinder is significantly reduced. The maximum reduction in ellipticity is 60% in the high-pressure section and 90% in the medium-pressure section. The maximum ellipticity is reduced from -1.47 mm to -0.34 mm. The improvement is evident and beneficial for the design and adjustment of the steam seal clearance.

To solve the problem that the negative pressure of gas turbine lubricating oil tank in existing units needed to be adjusted frequently, a scheme was proposed for optimizing the transformation of gas turbine lubricating oil exhaust fan by variable frequency conversion, and investigations were conducted on the remote adjustment effect of the negative pressure of lubricating oil tank in gas turbine within full load range. Operation data show that the negative pressure can be flexibly and accurately controlled within the specified value range after the variable frequency conversion, thus reducing the fire risk of gas turbine, improving the stability of lubricating oil exhaust system, reducing the power consumption rate of the plant, and achieving the purpose of energy saving and consumption reduction.

Based on the gas turbine performance model and combined with field temperature data and gas turbine performance test data, an economic model was established to predict the monthly and hourly variations of the unit output power, exhaust temperature and fuel flow rate more accurately. Through calculations using the economic model, the average monthly revenue of the entire project after replacing natural gas with membrane separation tail gas is approximately 48.523 2 million yuan, indicating significant economic benefits. Replacing natural gas with membrane separation tail gas as fuel not only achieves efficient operation of gas turbines, but also ensures the green utilization of membrane separation tail gas.

Focusing on medium-temperature and medium-pressure superheated steam power generation technology, the working principles and characteristics of two currently more mature technologies were introduced in detail. Taking a low-concentration gas oxidation device that produces superheated steam as the research object, specific plans were developed using these two power generation technologies, and a comparative analysis was conducted from both economic and technical perspectives. The research results show that plan 1 is superior to plan 2 in terms of technical feasibility, economic cost, and comprehensive benefit, and it is more suitable for application in the field of superheated steam power generation of low-concentration gas oxidation devices. The findings can serve as a reference for the equipment selection and technologies application.

Taking a waste heat retrofit project of a 1 000 MW coal-fired unit in southern China as an example, and combining heat pump and air preheater bypass waste heat utilization technology, the waste heat in flue gas was deeply coupled with the waste heat in closed-loop cooling water to maximize the utilization of low-grade waste heat in closed-loop cooling water. Under design condition, the net coal consumption rate can be reduced by 3.87 g/(kW·h), with 0.25 g/(kW·h) of savings attributed to the waste heat in closed-loop cooling water. Under winter condition, the net coal consumption rate can be reduced by 3.16 g/(kW·h), with 1.34 g/(kW·h) of savings attributed to the waste heat in closed-loop cooling water. The static payback period for this retrofit scheme is 2.1 years. The economic performance of the unit can be effectively improved by utilizing low-grade waste heat to replace the high-grade steam thermal energy of steam air heater.

The electronic weighing coal feeder is an important auxiliary equipment in thermal power plants. Once a fault occurs, it will seriously affect the operation of the entire unit. The evaluation method of equipment health status can accurately reflect the status of the coal feeder and predict the future status of the equipment. By analysing the functions and common failures of the coal feeder, a health status evaluation model for the coal feeder was established. Combined with an expert knowledge base, a quantitative model integrating deviation and fluctuation indicators was proposed, and a comprehensive weighting method was used to calculate the health index of coal feeder equipment. Taking the CS2024 coal feeder as an example for testing and analysis, the results show that this method has high accuracy, practical value, and guiding significance in practical applications, and can provide a reference for the subsequent health status evaluation of electronic weighing coal feeders.

The finite element method was employed to simulate the working condition of the high-pressure and intermediate-pressure integrated inner casing of a 660 MW supercritical unit steam turbine under hydrostatic test conditions. The hydrostatic test plan and the bolt tightening force requirements were determined. Moreover, the hot-tightening nut rotation angle during installation was derived through practical application, forming a complete design and analysis process for the hydrostatic test of high-parameter cylinders. Through optimized design, the plan ensures the structural strength safety of the cylinders while effectively meeting the sealing requirements of the hydrostatic test. The research results provide a reference for the hydrostatic test of other high-parameter units.

During the pyrolysis process of large-sized biomass particles, significant temperature gradients develop within the particles, which have an important impact on the heat transfer and reaction processes. Centimeter-scale biomass spheres were used as the research subject. Numerical simulations were conducted to investigate the effects of heating gas flow rate, temperature, and particle diameter on the internal temperature distribution, heat transfer characteristics, and weight loss rate/reaction time during pyrolysis. Results show that the temperature distribution along the particle diameter in the flow direction is U-shaped. Compared with the flow rate and temperature of the heating gas, the particle size has a more significant influence on the pyrolysis process. The pyrolysis time required for a particle with a diameter of 30 mm is 10.31 times that of a particle with a diameter of 5 mm. A weight loss model for particle pyrolysis based on back propagation (BP) neural network was established, which can effectively reduce computational costs while accurately predicting the heat transfer and reaction characteristics during the pyrolysis process. This approach is importance for the control of the pyrolysis process and the design of pyrolysis reactors.

The impact of adopting an integrated steam chamber structure in the cylinder on stiffness and flange sealing was discussed. Through finite element calculations and analyses, compared with the conventional independent steam chamber structure, the integrated design can not only significantly reduce the deformation of the cylinder upper arch, avoid the friction between the steam chamber seal and the rotor during operation, but also reduce the deformation of the opening at the upper cylinder steam chamber, and solve the problem of performance reduction of the flange sealing caused by deformation. Cylinders with an integrated steam chamber structure can meet the requirements for long-term, efficient, and safe operation of the unit and also provide an engineering example for designing steam turbines with higher extraction steam pressures.

Based on the business application scenarios of the electric power design industry， the digital and intelligent upgrading paths of the industry were deeply analyzed. Firstly， the significance of the artificial intelligence （AI） leadership system and the plan for its establishment were elaborated. Secondly， the AI multi-application scenarios covering administrative office work， business management， design production， and customer service were built according to the characteristics of the enterprise. Through the application of AI， enterprises can comprehensively enhance design quality and work efficiency. In the technical implementation aspect， the principles， characteristics and typical applications of the current mainstream large model modes were analyzed， and the selection and implementation principles for electric power design enterprises were given. A systematic AI technology application framework is conducive to improving the design quality and efficiency of enterprises， and has reference significance for the digital transformation and upgrading of the traditional electric power design industry.

To systematically solve the overtemperature problem of the converters in aged wind turbine generator sets， taking a 1.5 MW wind turbine generator set that has been in operation for more than 10 years as an example， a cooling system renovation plan was proposed based on the existing main defects and faults of the converter system of this type of wind turbine generator set， combined with the cooling and heat dissipation methods. Through the comparison and analysis of the measured data of the unit before and after the renovation， it is confirmed that the renovation measures can effectively reduce the operating temperature of the frequency converter， significantly reduce the frequency of faults， and significantly improve the operational reliability of the wind turbine generator set. Practice experience has proved that the two-phase flow heat dissipation technology applied in the renovation is mature， reliable， and economically viable.

With the development of large steam turbine generator sets towards greater capacity，the lubricating oil system，as a key auxiliary system，faces new challenges in terms of reliability. The common issues in the commissioning process of the lubricating oil system were systematically analyzed， including low oil pressure， delayed interlocking of oil pumps， lag in pressure signals， and abnormal system vibration. In response to these issues，system improvements were carried out through measures such as optimizing the starting mode of the direct current oil pump，improving the high-level oil supply system，enhancing the pressure measurement system，and applying intelligent vibration control. The practical application effect of a 530 MW unit shows that after the improvement，the minimum oil pressure of the system increases by 132%，the dynamic response time shortens by 40%，and the amplitude of pressure fluctuation decreases by 37.5%.

After the major overhaul of a 350 MW steam turbine unit， abnormal vibration occurred at both ends of the steam turbine shaft system. By analyzing the vibration mechanism through spectrum analysis and adjusting the data through experiments， it is found that the high and medium pressure rotors produce unstable vibration under the combined action of steam flow disturbance force and unbalanced centrifugal force. The vibration value is reduced through fine dynamic balance adjustment. Due to insufficient stiffness of the end bearing， the rotor of the exciter undergoes a vibration step change under the influence of unbalanced excitation force. By increasing the load on the end bearing and reducing the unbalanced excitation force， the unstable vibration problem of the exciter rotor is effectively solved.

Under the dual carbon policy framework， the new power system introduces new flexibility requirements for coal-fired power units，including rapid start-stop operations and deep peak regulation. During deep peak regulation，the rapid load fluctuations of units lead to substantial variations in water-steam flow rates and steam parameters. This significantly complicates the maintenance of water-steam quality control and increases the risks of stress corrosion fatigue on thermal equipment，thereby threatening the safe and stable operation of the units. A systematic analysis was conducted on how the deep peak regulation process affects steam-water parameters and quality control，as well as corrosion and scaling in thermal equipment，and the underlying causes of these issues were examined. Six major problems were summarized，including inadequate feedwater control and increased steam carryover，corrosion and scaling of the furnace heating surfaces and hydrodynamic instability，abnormal fluctuations in steam temperature，intensified water erosion of the final stage blades of the steam turbine，excessive dissolved oxygen in condensate water and feedwater，and lagging regulation of the chemical dosing system. The proposed multi-dimensional risk prevention measures provide theoretical guidance and practical reference for the optimal control of water-steam systems in coal-fired power enterprises during deep peak regulation operations.

With the development of thermal power units towards higher parameters and larger capacities，the amount of data that needs to be monitored during the operation of turbo-generator set is increasing. The widely used expert diagnosis systems have severely impacted fault discrimination accuracy. To address this problem，a new steam turbine fault diagnosis method based on deep learning technology was proposed. Firstly，the original signals were reconstructed and output by using the autoencoder network. Secondly，the convolutional neural network（CNN）was employed to reduce the number of input parameters in the fully connected layers through convolution and pooling operations，while extracting data features and combining them into deeper，higher-dimensional data. Finally，the fully connected layers were used for output prediction and classification. Engineering application results demonstrate that this method can adaptively extract features of different fault locations and types in steam turbine systems under various operating conditions，accurately identifying equipment health status. Its discrimination accuracy is significantly higher than that of the currently widely used expert diagnosis systems.

In order to optimize the control effect of the boiler fans in cogeneration power plants and improve the combustion efficiency and energy efficiency level，a frequency prediction model suitable for boiler fans was developed. Two prediction models were constructed using the fan performance method and the boiler operating condition method， and the two models were verified based on the actual data. The results show that the boiler operating condition method has higher accuracy in fan frequency prediction compared with the fan performance method. The frequency prediction relative errors of the primary fan and the secondary fan have decreased to 0.03% and 0.39%，respectively. Therefore， the prediction model established by the boiler operating condition method can provide more reliable fan frequency prediction results for the operators of cogeneration power plants，which is conducive to achieving the optimal control of boiler fans operation，reducing fan energy consumption，and improving the overall production efficiency of cogeneration power plants.

In order to achieve the economic evaluation and decision-making guidance of peak regulation in the operation mode of cogeneration units coupled with electric boilers，a peak regulation decision-making model for the unit was established. Through big data tools such as data mining technology and back propagation （BP） neural network，a prediction model for energy consumption indicators of cogeneration units was constructed to achieve precise calculation of various cost and revenue indicators of the unit revenue model. Meanwhile，an economic evaluation method for peak regulation of thermal power units was proposed. It comprehensively considered the coupled operation modes such as peak regulation，steam extraction heating，and electric boilers. By calculating the revenue of the full-load operation in real time，it provided guidance for peak regulation decisions based on the optimal operating income. The results show that when the heat load is higher than the critical value，the operation mode of giving priority to starting the electric boiler of the unit is more economical. The critical heat load of the unit is determined by the ratio of the unit price of standard coal to the heat price. During the heating period，to maximize the revenue of the electric boiler，the unit should operate below the critical heat load. The critical peak regulation compensation correction coefficient of the unit is mainly affected by the heat load and the non-peak regulation allocation electricity price. Referring to this coefficient to guide the peak regulation decision-making of the cogeneration units can maximize the operating income of the unit.

To further enhance the peak regulation capability and reduce fuel costs of coal-fired power plants， achieving multi-coal types compartmentalized storage and flexible blending， a 650 MW ultra-supercritical coal-fired unit was taken as the research subject to study the rapid switching technology of high/low calorific-value coals in raw coal bunkers， which was suitable for fast load changes in high-parameter coal-fired units. Meanwhile， based on the actual production and operation of the case unit， a comparative analysis was conducted on various schemes， including partition plate， shrimp-shaped outer bunker， conduit connection between two raw coal bunkers， and parallel screw conveyor bunker separation. Simulation software was also used to assist in the scheme design. Results show that the conduit connection between two raw coal bunkers scheme enables rapid switching of high/low calorific-value coals in the coal feeder， meeting the requirements for efficient and economical operation of the system.

In order to enhance the competitive advantage of industrial steam turbines in the thermoelectric field， increasing the pressure in the turbine impeller chamber can effectively improve the internal efficiency of the entire machine. However，the increase of impeller chamber pressure poses higher requirements for the strength and low cycle fatigue life of the high pressure inner cylinder. Therefore，the finite element method and the theory of low cycle fatigue life were adopted to analyze the strength and low cycle fatigue life of the high pressure inner cylinder. The research results show that stress concentrations are prone to appearance at the connection points of the inner cylinder structure and the areas with sudden shape changes，leading to fatigue damage. The research results can provide a theoretical basis for the design and optimization of the inner cylinder of industrial steam turbines.

To address the hydrodynamic instability and combustion disturbances of a 600 MW supercritical oncethrough boiler at Ligang power plant during deep peak regulation down to 20% rated load，a hydrodynamic calculation model for the water wall and a coupled simulation platform for the combustion system were established based on the actual boiler structure and operational parameters. Through the combination of numerical simulations and field tests， the mass velocity distribution characteristics，wall temperature deviation，and pulsation risks under low-load conditions were quantitatively analyzed. A dynamic control strategy based on the optimization of coal mill combinations was proposed. The results show that adopting the mid-upper coal mill combination（B+C+D）with a staged air distribution strategy can reduce the water wall mass velocity deviation to 18.7%. The research findings provide a theoretical basis for the deep peak regulation of supercritical units.

The CAP1000 unit is a representative of advanced pressurized water reactor nuclear power technology independently developed in China. The overspeed protection system of its steam turbine is the core to ensure the safe operation of the unit. To identify an optimal solution，the traditional "mechanical and electrical overspeed" scheme and the innovative "dual electrical overspeed" scheme were compared，and an analysis was conducted from the aspects of technical compliance，safety redundancy，operation and maintenance efficiency，and economy，supported by a case study. The results demonstrate that upgrading from mechanical overspeed protection to independent electrical overspeed protection conforms to the technical trends and relevant standards of the nuclear power industry. It enhances protection response speed，simplifies operation and maintenance，and delivers both safety and economic benefits. The research findings can serve as a reference for the design and retrofit of CAP1000 units.

Aiming at the problems of low initial discharge field strength and easy occurrence of corona in stator coil bars and windings under high-altitude conditions，the research on the anti-corona performance of stator coil bars and windings was conducted. Firstly，the impact of different altitudes on the initial discharge field strength at the end of stator coil bars was analyzed. Secondly，the key parameter ranges of anti-corona materials，the basic requirements for the optimization design of anti-corona structures，the field strength distribution at the corners of stator coil bar conductors，and the equipotential layer treatment technology in the slot section of conductors were introduced. Finally， anti-corona technologies for the end of stator windings were presented，and the influence of the ground clearance at the end of stator windings on end discharge was analyzed. The research results indicate that the anti-corona technologies for individual stator coil bars and stator windings have laid a solid foundation for enhancing the anti-corona performance of stator coil bars and windings in high-altitude impulse hydrogenerator units.

Establishing an accurate and efficient integrated energy system model on the source side of thermal power plants is crucial for optimizing the system management process and improving the safety and economy of operation，and is an important reference for the planning and transformation of thermal power plants. A digital twin operation and maintenance model of the integrated energy system on the source side of thermal power plants based on feedforward neural networks was proposed. This system took the thermal power unit as the core，coupled three types of renewable energy，namely biomass gasification，waste gasification and dried sludge，at the input end，and supplied four types of energy products，namely cold，heat，steam and electricity，at the output end. The feedforward neural network was trained using the computational data provided by the physical model，and its optimal hyperparameters were calculated. The corresponding neural network model was constructed，and finally a digital twin model was formed. Through comparison and verification with the physical model，it is found that this digital twin model has good calculation accuracy and high calculation efficiency，and can complete the prediction within milliseconds.

Experimental study was carried out to investigate the effect of H₂O on the mercury removal performance of modified rice straw coke under conventional combustion conditions. Experiments were conducted to get rice straw coke particles prepared from rice straw in Jiangsu region and modified by chemical impregnation of NH₄Cl combined with HNO₃. A fixed-bed experimental platform was utilized to simulate the flue gas environment of coalfired power plants，through which the mercury removal effect of the modified rice straw coke was tested. The results show that the addition of H₂O inhibits the mercury removal effect of modified rice straw coke under conventional combustion atmosphere（composed of N₂ and 6% O₂）. Further analysis reveals that the increase of H₂O concentration leads to a gradual decrease of mercury adsorption，and the mercury adsorption forms on the surface of coke samples are mainly Hg⁰ and HgO under the H₂O-containing atmosphere，without changing the main adsorption forms. However，H₂O dissociates the oxidizable OH，weakens the Hg⁰ competitive adsorption，and provides additional electrons for the reduction of Hg²⁺. Excessive H₂O concentration will exacerbate the segregation of Hg⁰ and CO₂， leading to the decomposition of unstable oxidation products such as HgCl₂，thus inhibiting the overall Hg removal effect of the adsorbent.

With the rapid development of steam turbine technology and the continuous emergence of various new types of steam turbine generator sets， the traditional frame-type foundation has been continuously optimized into a complex foundation with irregular structure. It is difficult to establish a concise and reasonable mechanical model and carry out a correct dynamic analysis for this kind of irregular space structure with multiple mass points and degrees of freedom. Taking the 9F-class gas generator set as an example， based on the vibration response characteristics of components such as the foundation base plate， column pier， and frame under the action of horizontal radial， axial， and vertical disturbing forces， four basic vibration modes with single mass points and single degrees of freedom were established by applying the principle of structural dynamics. Simple dynamic analysis and vibration verification were carried out， and the theoretical calculation values were verified with the on-site measured data. The research results prove that the dynamic analysis and vibration calculation method for the complex foundation of this large-scale power machine is reasonable and feasible， and has certain reference value.

Under special operating conditions， such as in the event of a condensate system accident or condensate throttling for primary frequency regulation of the unit， the deaerator water level may drop. Blindly and rapidly replenishing condensate when the deaerator water level is low can lead to a rapid decrease in deaerator pressure， resulting in insufficient net positive suction head （NPSH） available for the feedwater pump. By simplifying the transient mass-energy balance calculation model of the deaerator， the calculation formula for the conservative maximum condensate flow rate allowed to prevent insufficient NPSH of the feedwater pump was obtained. The calculation results using design parameters are consistent with the parameter variation laws of deaerator simulation modeling and transient calculation. Based on this， a deaerator water level control method was proposed to prevent insufficient NPSH for the feedwater pump by limiting the condensate flow rate. The method has been verified through experiments and can ensure that the NPSH of the feedwater pump is always sufficient.