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    Boiler Technology
  • Boiler Technology
    System Design of 300 MW S-CO2 Secondary Reheating Coal-fired Boiler
    WANG Yang, ZHENG Zhimin, LI Pengpeng, GU Mingyan
    2022, 42(3): 197-206. https://doi.org/10.19805/j.cnki.jcspe.2022.03.001
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    Based on the calculation method of furnace zoning heat transfer, a boiler system for 300 MW coal-fired power station was designed by using a supercritical CO2 (S-CO2) Brayton cycle system with primary intercooling and secondary reheating & regenerating. The effects of the boiler zoning layout on the temperature distribution along the gas-cooled wall and furnace as well as the pressure drop of the working fluid were analyzed emphatically. Results show that under the design load, when the superheated gas-cooled wall is located at 0.71 of the chamber height, the flue gas temperature is within a reasonable range, and the furnace gas-cooled wall temperature has a wide safety margin,meanwhile the design cost is relatively low. Moreover, the cycle efficiency of the proposed circulation system can reach 51.82%, which is 1.79% and approximately 11% higher than that of a S-CO2 primary reheating coal-fired boiler and a conventional steam boiler at the same class respectively.
  • Boiler Technology
    Numerical Simulation on Co-combustion Characteristics and NOx Formation Behavior of Coal with Municipal Sludge
    DING Xian, WU Helai, ZANG Jiannan, KANG Zhizhong
    2022, 42(3): 207-214. https://doi.org/10.19805/j.cnki.jcspe.2022.03.002
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    Co-combustion process of pulverized coal and municipal sludge was simulated by the customized combustion reaction model, while the combustion characteristics, NOx volume fraction distribution and formation behavior under different mass ratios of the sludge were studied. Results show that sludge can promote the combustion of pulverized coal in the first stage obviously, and it can promote the combustion of pulverized coal in the second stage with the ratio less than 3% and inhibit the combustion of pulverized coal with the ratio more than 6%. Nitrogen exists in various forms near the outlet of the burner, where most of NH3 is converted to HCN and a small amount of NH3 is converted to HNO and NH2, etc. In the second half of the recirculation zone, HCN volume fraction is significantly reduced, NO volume fraction rises, and part of NO is reduced to HCN and HNO in the combustion. NOx is mainly generated in two stages of coal combustion. In the first stage, NO generation process is mainly the oxidation of NH by O and O2, and the oxidation of N by O2;The second stage is mainly the oxidation of NH by O and the oxidation of N by CO2. The reduction of NO to HCN by CH3 is the main process of NO reduction in two stages.
  • Boiler Technology
    Rapid Evaluation Method of Coal Property Using PL-Raman Spectroscopy
    YU Pengfeng, SU Pan, LIU Jiawei, ZHONG Yuxiu, XU Jun, SU Sheng, HU Song, XIANG Jun
    2022, 42(3): 215-220. https://doi.org/10.19805/j.cnki.jcspe.2022.03.003
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    PL-Raman spectroscopy of 15 kinds of typical Chinese raw coals was studied and three characteristic parameters were proposed to represent the spectral characteristics. Quantitative relationships between these parameters and moisture content, volatile content, ignition temperature and burnout temperature were set up. Then rapid evaluation method of coal property using PL-Raman spectroscopy was proposed. Results show that the fluorescence characteristics of coal are synthetically determined by moisture and volatile content, and the fluorescence intensity increases significantly with the increase of moisture and volatile content. There are fairly good relationships between characteristic parameters and volatile content, C/H mass ratio and combustion characteristic temperature, whose correlation coefficient is high. This method can be used to evaluate coal property and combustion characteristics.
    • Steam Turbine and Gas Turbine
  • Steam Turbine and Gas Turbine
    Effects of Inlet Preswirl on the Unsteady Flow Excitation Rotordynamic Characteristics of Labyrinth Seal with Tooth Wear
    CHEN Yaoxing, LI Zhigang, LI Jun, YE Lv
    2022, 42(3): 221-228. https://doi.org/10.19805/j.cnki.jcspe.2022.03.004
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    In order to study the effects of inlet preswirl on the unsteady flow excitation rotordynamic characteristics of labyrinth seal with tooth wear, the unsteady Reynolds-averaged Navier-Stokes (URANS) solution based on multi-frequency elliptical orbit rotor whirling model was used to analyze variation of the seal leakage mass flow, average flow circumferential velocity and rotordynamic characteristic coefficient at two inlet preswirl ratios under the following circumstances, such as unworn structure, unbending wear structure and partial bending wear structure. Results show that at two inlet preswirl ratios, increasing the wear clearance and labyrinth tooth bending would increase the seal leakage mass flow. At the inlet preswirl ratio of 0, the increase of seal leakage mass flow would weaken the circumferential drag effect of the rotor, and thus the average flow circumferential velocity in the chamber decreases, which leads to the decrease of the negative tangential flow excitation force in the opposite direction of rotor whirl, and the stability of seal rotor decreases. At the inlet preswirl ratio of 0.45, the average flow circumferential velocity is not affected by the wear structure of labyrinth tooth. Therefore, the circumferential momentum in the chamber would increase after the wear of labyrinth tooth, the tangential flow excitation force in the same direction as the rotor whirl increases, and the stability of the seal rotor decreases.
  • Steam Turbine and Gas Turbine
    Research of High-temperature Adaptability on Compressor Blade Coatings of Gas Turbines
    ZHOU Xia, WANG Chao, LIANG Yunfei, HE Lei
    2022, 42(3): 229-234. https://doi.org/10.19805/j.cnki.jcspe.2022.03.005
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    In order to apply coatings to more grade blades in the compressor, the high-temperature adaptability of inorganic salt aluminum coating and aluminum-based hard coating was studied. The thickness, surface roughness, microstructure, element distribution and tensile bonding strength of coatings were tested by optical microscope, roughness meter, scanning electron microscope, energy dispersive spectroscopy and tensile testing machine. Results show that for the inorganic salt aluminum coating, the thickness is 40~60 μm, and the surface roughness of the sprayed coating and the heated coating is 0.570~0.685 μm and 0.734~0.842 μm, respectively; the microstructure remains stable within 460 ℃ and 2 000 h; during the thermal failure process, the aluminum in the coating diffuses rapidly to the substrate, the metal substrate oxidizes and the tensile bonding strength decreases. For the aluminum-based hard coating, the thickness is 8~12 μm, and the surface roughness of the sprayed coating and the heated coating is 0.324~0.486 μm and 1.054~1.275 μm, respectively; the microstructure remains stable within 460 ℃ and 1 001 h; (Fe, Cr) Al intermetallic compound occurs during the thermal failure process, and the tensile bonding strength maintains at 40 MPa. Aluminum-based coatings are more unstable with the higher heat treatment temperature and the longer time. When the temperature is not higher than 460 ℃, the service requirements may be met.
    • Turbo-Generator
  • Turbo-Generator
    Analysis of Backward Whirl of Generator Set Rotor Induced by Unbalance
    ZHAO Bo, HE Guoan, KAN Xuanen, JIANG Guangzheng, CHANG Dongfeng
    2022, 42(3): 235-241. https://doi.org/10.19805/j.cnki.jcspe.2022.03.006
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    Aiming at the problem of rotor backward whirl caused by unbalance in the vibration test of several large turbine generator sets, a dynamic model of the rotor system with non-axisymmetric support was established, and the response of the system to the unbalanced excitation force was derived by the mode-superposition method to analyze the influence of the unbalance vector on the rotor whirl direction. In addition, the mechanism was confirmed by vibration test results of three 600 MW steam turbo-generator sets before and after the on-site dynamic balance. Results show that even under the condition of avoiding the critical speed region, when multi-plane or distributed unbalance occurs in the anisotropic support rotor system, as long as the axial position, size and angle of the unbalance meet a certain relationship, it will lead to particular sections of the rotor backward whirl at working speeds.
    • Automatic Control
  • Automatic Control
    Active Disturbance Rejection Control of Core Power for Accelerator Driven Subcritical System
    GUO Wei, SHI Bo, ZHANG Yilin
    2022, 42(3): 242-248. https://doi.org/10.19805/j.cnki.jcspe.2022.03.007
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    An ADS core power control method based on nonlinear active disturbance rejection control (ADRC) technology was proposed. Firstly, the nonlinear mathematical model of ADS core system was established by using point kinetic equations with an external neutron source and the energy conservation equation. The model was linearized based on micro-disturbance linearization method, so as to obtain the dual input and dual output transfer function model. Secondly, the ADRC system of core power was designed based on the proposed model, and the controller parameters were adjusted by separation principle. Finally, both the ADS core nonlinear model and ADRC control model were built by Matlab, and the performance between ADRC control and PID control was compared. Results show that the designed control system shows better control effect, proving that the application of ADRC technology on ADS core power control is feasible.
    • Environmental Protection Technology and Equipment
  • Environmental Protection Technology and Equipment
    Chemical Desorption and Mineralization of CO2 in TEA-rich Solution by Ca(OH)2
    ZHANG Weifeng, WANG Lulu, WANG Qiuhua
    2022, 42(3): 249-254. https://doi.org/10.19805/j.cnki.jcspe.2022.03.008
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    In order to explore the desorption performance of TEA-rich solution under the chemical desorption mode of adding Ca(OH)2, the desorption effects of different factors on rich solutions of TEA, TEA+MDEA and MDEA were studied by single factor method, and then the regeneration performance of TEA rich solution was further analyzed through multiple absorption-desorption experiments. Results show that the following factors have a certain influence on the desorption effects of rich solutions of TEA, TEA+MDEA and MDEA, such as n(Ca)/n(C), pH value, etc. In general, the desorption effect of TEA-rich solution shows the best, followed by TEA+MDEA and MDEA. The desorption rate of TEA-rich solution reaches 82.85% at the n(Ca)/n(C)=1∶1, pH value of 10, temperature of 20 ℃, CO2-loading of 0.4 mol/L, stirring rate of 800 r/min and mixing time of 10 min. After five times of absorption-desorption experiments, the desorption rate of TEA-rich solution could be remained about 80%, indicating that it has good desorption performance under the chemical desorption mode of adding Ca(OH)2.
  • Environmental Protection Technology and Equipment
    Experimental Study on Convective Evaporation Characteristics of Single Desulfurization Wastewater Droplet at Elevated Temperature
    ZHAO Ning, FENG Yongxin, LIN Tingkun, XIE Zhiwen
    2022, 42(3): 255-262. https://doi.org/10.19805/j.cnki.jcspe.2022.03.009
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    In order to explore the evaporation mechanism of desulfurization wastewater droplets in flue gas, single droplet drying (SDD) device was adopted. The evaporation characteristics of wastewater during drying process were analysed, and the influence of drying temperature, water quality and initial particle size on evaporation process of single droplet were obtained. Using lumped reaction engineering approach (L-REA) model to fit experimental data, an activation energy-based drying kinetic model was established. Results show that due to the accumulation of solutes on its surface,the evaporation process of single desulfurization wastewater droplet involves significant crust formation and reduction of evaporation rate. After that, the rapid vaporization of remaining moisture at elevated temperature causes its expansion and partial fragmentation.The increase of drying temperature and decrease of initial particle size are benefitial to the evaporation of single wastewater droplet,and the addition of suspended solids can reduce the particle size of final product. The obtained L-REA model by experimental data can describe the drying process well. At drying temperature of 300 ℃, the total evaporation time of single wastewater droplet with initial particle size of 50 μm is within 0.05 s.
  • Environmental Protection Technology and Equipment
    Effect of Scale Inhibitor on Crystallization Characteristics of Gypsum in Wet Flue Gas Desulfurization
    LI Gang, XIAO Haiping, LIANG Luntao, SUN Baomin, LI Xiaofeng
    2022, 42(3): 263-268. https://doi.org/10.19805/j.cnki.jcspe.2022.03.010
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    The gypsum crystallization reaction experiment under the action of scale inhibitor was carried out on the crystallization test bench to study the nucleation, growth and morphology change of gypsum. Results show that the scale inhibitor could delay the induction time of gypsum crystallization and inhibit gypsum nucleation.The scale inhibitor is adsorbed on the prenuclear cluster or the surface of the embryo, resulting in the crystal of gypsum distortion and particle size increase,which promote the growth of gypsum. When the concentration of scale inhibitor is increased from 1 mg/L to 20 mg/L, the nucleation inhibition indexes of non-phosphorus and phosphorus series scale inhibitor are increased by 15~16 times and 13~14 times, and the growth rates of gypsum are increased by 8~9 times and 6~7 times, respectively. The distorion of scale inhibitor leads to the transformation of the gypsum crystal from needle to sheet and cluster shape. The radius of gypsum crystal cluster increases with the increase of scale inhibitor concentration.
    • New Energy
  • New Energy
    Effect of Soil-Structure Interaction on Seismic Behaviors of 15 MW Wind Turbine
    MEI Xuan, YANG Yang
    2022, 42(3): 269-275. https://doi.org/10.19805/j.cnki.jcspe.2022.03.011
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    In order to investigate the effect of soil-structure interaction (SSI) on seismic behavior response of next-generation large offshore wind turbines, through the secondary development of the open source software FAST, a seismic dynamics simulation model of offshore wind turbine was established by using the modal acceleration method to calculate the seismic load. Accordingly, the characteristics of the vibration at the top of the tower and the load variation of the support structure of the 15 MW monopile wind turbine under the operation and shutdown conditions were investigated considering and neglecting the soil-structure coupling effect. Results show that although the SSI has a small effect on the severity of tower top vibration induced by earthquake, it suppresses the recovery of lateral vibration during shutdown to a certain extent; ignoring the soil-structure coupling effect will lead to a lower predicted value of the structural bending moment at the mud surface by about 29.6%; when considering the SSI effects, the in-plane bending moment still maintains a large change in magnitude after the earthquake ends; for the seismic design of offshore wind power structures, it should consider increasing the system damping to reduce the in-plane loads caused by seismic excitation in time.
    • System Engineering
  • System Engineering
    Research on Multi-time Scale Rolling Optimal Operation Method of Combined Cooling, Heating and Power System
    WANG Zhi, TAO Hongjun, ZHANG Ling
    2022, 42(3): 276-285. https://doi.org/10.19805/j.cnki.jcspe.2022.03.012
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    In order to solve the problem of energy mismatch between source and load, a multi-time scale rolling optimization operation method for CCHP systems was proposed. The unit output plans was formulated level by level according to the two stages of day ahead and intraday. A day-ahead optimization model was constructed with the lowest day-ahead operating cost as the goal, and a intraday rolling optimization model was made with the lowest power purchase cost and the penalty cost of energy storage output changes in the rolling time domain as the goal. Thus, a smooth output plan of CCHP system was obtained. The impact of multiple energy storage modes on the operating economy of the CCHP system was considered in the day-ahead optimization, and the optimum rolling period of 4 hours was determined in the intraday rolling optimization stage. Results show that the multi-energy storage modes can improve the operating economy of the CCHP system. Multi-time scale rolling optimization can not only enhance and ensure the operating economy of the CCHP system, but also effectively reduce the impact of source load fluctuations on the actual system operation.
  • System Engineering
    Comprehensive Performance Analysis of Organic Rankine Cycle System with Variable Heat Source
    LI Huijun, JIANG Changhui, FAN Wei, WANG Qingwu
    2022, 42(3): 286-292. https://doi.org/10.19805/j.cnki.jcspe.2022.03.013
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    For variable temperature heat source of 120~150 ℃, exergy efficiency and net present value (NPV) were used as objective functions to establish a multi-objective optimization model of ORC system. The weight coefficients were determined by the Pareto boundary solution, and the comprehensive objective function Fx was established. The influence of the evaporation temperature and heat source parameters on the comprehensive performance of the system was analyzed in the given conditions. Results show that the overall performance of R1234ze is better than that of R245fa and R134a. The weight coefficients determined by the α method and the Pareto boundary solution are different, but the system operating parameters corresponding to the optimization indicators of each working fluid are similar, and the error is not large. When the evaporation temperature is around 361 K, the relationship between the system Fx values corresponding to R1234ze and R134a changes.