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    Power System Analysis
  • Power System Analysis
    Economic Operation Strategy for Deep Peak Regulation of a 350 MW Combined Heat and Power Unit
    ZHANG Yanbin, LI Juhua, ZHANG Chunmei, PANG Xiaoping, ZHANG Xiong
    2025, 39(3): 141-149. https://doi.org/10.19806/j.cnki.fdsb.2025.03.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Power System Analysis
    Analysis on Thermal Performance and Deviation of a 660 MW Coal-fired Unit Under Deep Peak Regulation Condition
    LIN Qiang, HAN Huaiyuan, YANG Weijie
    2025, 39(3): 150-154,161. https://doi.org/10.19806/j.cnki.fdsb.2025.03.002
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Power System Analysis
    Operation Mode and Economic Benefits Analysis of Back Pressure Turbine Heat Supply in a Thermal Power Unit with Deep Peak Regulation
    SHEN Xiangyu, SUN Deyu, HE Xiang, FAN Chenghao, ZHAO Xu
    2025, 39(3): 155-161. https://doi.org/10.19806/j.cnki.fdsb.2025.03.003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Power System Analysis
    Thermodynamic Analysis and Optimization of Supercritical Carbon Dioxide Brayton Cycle
    ZHANG Nile, WANG Huanan, WEN Jili
    2025, 39(3): 162-166,179. https://doi.org/10.19806/j.cnki.fdsb.2025.03.004
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
    • Power Equipment Optimization
  • Power Equipment Optimization
    Design of Buckstay Corner Components for Supercritical Boiler
    GAO Fei, ZHANG Xin, Lü Hongbin
    2025, 39(3): 167-170. https://doi.org/10.19806/j.cnki.fdsb.2025.03.005
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Power Equipment Optimization
    Calculation and Analysis of High-pressure Cylinder Leakage Fault in a Condensing Steam Turbine
    YE Pengzhen
    2025, 39(3): 171-174,179. https://doi.org/10.19806/j.cnki.fdsb.2025.03.006
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Power Equipment Optimization
    Analysis and Treatment on High Vibration After Switching the Heating Mode of a Steam Turbine
    CUI Yongjun, ZHAO Tian, YANG Zhi, YANG Junjun, LIU Shaopei, LIU Xuguang
    2025, 39(3): 175-179. https://doi.org/10.19806/j.cnki.fdsb.2025.03.007
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Power Equipment Optimization
    Analysis on End Sealing of High-pressure Cylinder in a Russian-made 1 000 MW Nuclear Power Steam Turbine
    DOU Jianye, QIN Zhiwen, ZHANG Han, LI Zhanzheng, LU Luyi, WANG Kun
    2025, 39(3): 180-186,210. https://doi.org/10.19806/j.cnki.fdsb.2025.03.008
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Power Equipment Optimization
    Analysis and Improvement of High-pressure Bypass Valve Stem Fracture of a Supercritical 600 MW Unit
    WU Tao, WANG Miaomiao, WANG Yanfeng
    2025, 39(3): 187-193. https://doi.org/10.19806/j.cnki.fdsb.2025.03.009
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Power Equipment Optimization
    Application and Energy-saving Retrofit on a New Type of Drainage Device for Gland Steam Condenser
    PAN Junsheng
    2025, 39(3): 194-197. https://doi.org/10.19806/j.cnki.fdsb.2025.03.010
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
    • Digitalization and Intelligentization
  • Digitalization and Intelligentization
    A General Control Method for Fuel Flow in an F-class Gas Turbine
    SHEN Xinjun, ZHANG Xuan, ZHANG Xuyan, LI Junkun, WANG Fuzhong, ZHAO Yu, XIE Jinyu
    2025, 39(3): 198-204. https://doi.org/10.19806/j.cnki.fdsb.2025.03.011
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.
  • Digitalization and Intelligentization
    Structure Design and Experimental Analysis of Spiral Shaft for Biomass Fuel Compression Conveying
    JIA Xiaolong, GONG Shuguang, ZHANG Huiming, LIU Hailun, TANG Fang, LIU Linhui
    2025, 39(3): 205-210. https://doi.org/10.19806/j.cnki.fdsb.2025.03.012
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    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.