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    Boiler Technology
  • Boiler Technology
    Analysis of Mass Transfer in Flue Gas Dehydration of Coal-fired Units Based on Inorganic Porous Membrane Gas Separation
    TENG Da, LI Ang, LI Tielin, AN Liansuo, SHEN Guoqing
    2021, 41(3): 173-181. https://doi.org/10.19805/j.cnkij.cspe.2021.03.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To reduce the flue gas humidity of coal-fired units, a gas separation technology based on inorganic porous membrane was adopted, while the main mass transfer process of flue gas in the inorganic porous membrane was analyzed. Combined with the technological systems for vacuum membrane separation, purge membrane separation, circulating water membrane separation and absorbent membrane separation, the effects of membrane pore size and driving force on the permeation flux and separation coefficient of the flue gas were analyzed. Results show that in specific mass transfer process, it is impossible to achieve effective flue gas dehydration only by the membrane due to the separation properties of the material. However, the effect of flue gas dehydration could be significantly improved by adopting suitable separation process and choosing appropriate material of the membrane; the pore size of membrane directly affects the permeation flux of gas components in the flue gas, and the overall mass transfer characteristics of 2 μm ceramic membrane are better than that of 30 nm ceramic membrane; the permeation flux and selective separation coefficient of the absorbent membrane separation system are the highest, and the purge membrane separation system with permeating gas is the most feasible.
    • Steam Turbine and Gas Turbine
  • Steam Turbine and Gas Turbine
    Analysis of Off-design Characteristics of Supercritical CO2 Single-stage Axial-flow Turbine
    WANG Zhi, LIU Yali, KUANG Xuanyi
    2021, 41(3): 182-188. https://doi.org/10.19805/j.cnkij.cspe.2021.03.002
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    A single-stage axial-flow turbine with a mass flow rate of 185 kg/s was designed using supercritical carbon dioxide as working fluid. The effects of pressure ratio, inlet temperature and rotation speed on the isentropic efficiency, output power and mass flow rate of the turbine were studied by thermal aerodynamic design, three-dimensional blade design and numerical simulation. Results show that the change of pressure ratio has the greatest effect on the isentropic efficiency of the turbine, and the change of inlet pressure has greater influence on the isentropic efficiency than the change of outlet pressure at the same pressure ratio. The change of rotation speed has secondary influence on the isentropic efficiency, and the change of inlet temperature has little influence on the isentropic efficiency. When the inlet pressure is changed by ±10%(about 1.5 MPa), the output power can be changed by ±32.65%(3.33 MW), the efficiency can be changed by ±3%(2.5%), and the mass flow rate can be changed by ±14.9%(27.4 kg/s).
  • Steam Turbine and Gas Turbine
    Research on Formation and Evolution of Stress on Hot Tearing in Gas Turbine Blades
    YANG Atao, GUO Xiong, LI Haisong, SHI Weijie, TAO Fei, WANG Haiyang, ZHANG Qiongyuan, YANG Zhaohong
    2021, 41(3): 189-194. https://doi.org/10.19805/j.cnkij.cspe.2021.03.003
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    To reveal the influence of stress on hot tearing in investment casting process, a high temperature turbine blade of a heavy-duty gas turbine was selected as the research object, which was formed by investment casing process. The formation and evolution of stress during solidification were studied by observing the macro and micro morphology of the hot tearing and combining with the numerical simulation software Procast to calculate the thermal stress in the solidification process at different positions of the blade. And the numerical calculation results and measured values of casting deformation were compared. Results show that the numerical results are in good agreement with the measured values. The formation of hot tearing is closely related to the evolution of stress, but stress is not the only condition for the generation of the hot tearing. In consideration of the complex effect of the shell on the stress of the blade, it is necessary to determine whether the displacement size of the shell is consistent with the amount of casting shrinkage, and the defect of hot tearing can be effectively eliminated by controlling or reducing the stress of the blade.
    • Automatic Control
  • Automatic Control
    Fuzzy Adaptive PID Control of Circulating Fluidized Bed Boiler Combustion System Based on Dynamic Universe
    LI Fengze, MA Suxia
    2021, 41(3): 195-200. https://doi.org/10.19805/j.cnkij.cspe.2021.03.004
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    The circulating fluidized bed(CFB)boiler combustion system is characterized by non-linear, strong coupling and time lag properties. Aiming at the control difficulty due to serious coupling between bed temperature and main steam pressure, a feedforward compensation decoupling controller was designed to reduce the coupling degree between them. Based on the fuzzy adaptive PID control for the decoupled independent loop, the idea of dynamic universe was introduced, and the range of fuzzy universe was adjusted by the adaptive expansion factor changing with the operating condition, so that the PID parameters KP, Ki and KD can be tuned more accurately online. Simulation experiment of fuzzy adaptive PID control in dynamic domain was carried out for the combustion system of a CFB boiler. Results show that compared with the traditional fuzzy PID control, the control quality for main parameters of the combustion system is improved by the dynamic domain fuzzy adaptive PID control, that is, the overshoot is reduced by 5% to 10% and the dynamic response speed could be increased by nearly 30%. The dynamic domain fuzzy adaptive PID control method has good adapt ability and robustness, which can meet the field requirements in thermal applications.
  • Automatic Control
    Study on Decoupling Control Characteristics of Supercritical Extraction Steam Turbine
    ZHENG Shaoxiong, CHEN Kang, FAN Gang, CHEN Kenan, GAO Chao, DAI Yiping
    2021, 41(3): 201-207. https://doi.org/10.19805/j.cnkij.cspe.2021.03.005
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    Taking a 350 MW supercritical extraction steam turbine as the object, the static decoupling control matrix of electrical load and heat load was determined according to its assembly drawing and working condition diagram. A simulation model of thermo-electric decoupling control system and its regulation objects was built based on the idea of modular modeling. The control characteristics of the connected and the non-connected regulation systems were simulated. Results show that the demand of electrical load change can be met by adjusting the opening of the high-pressure regulating valve and butterfly valve when the electrical load is disturbed. The static interference of the electrical load to the heat load is eliminated due to the integral action of the pressure PI controller. When the heat load is disturbed, the static interference of the heat load to the electrical load is eliminated due to the function of decoupling control. The application of connected regulation system can reduce the dynamic interference, shorten the transition process, improve the dynamic response characteristics, and finally realize the static decoupling control between the heat and the electrical loads.
    • Monitoring and Measurement
  • Monitoring and Measurement
    Analysis of Measurement Error of Journal Center Position Caused by Thermal Stress
    XU Zewei, YANG Jiangang, SHEN Deming
    2021, 41(3): 208-213. https://doi.org/10.19805/j.cnkij.cspe.2021.03.006
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    To study the influence of sliding bearing shell deformation on the measurement result of journal center position, a solution model of temperature and pressure fields of the sliding bearing was established considering the gas-liquid two-phase flow, the temperature-viscous effect. Taking a sliding bearing as an example, temperature and pressure distribution of the bearing shell and the deformation caused by the former were calculated while the effect of bearing shell deformation on journal center position was furtherly analyzed. Moreover, combined with an engineering project, the abnormal deviation of journal center position occurred in the process of speed-up and operation under load was explained. Results show that bearing shell can be deformed by temperature and pressure, and the amount of deformation due to the temperature is greatly higher than the pressure. Unconsidering the bearing shell thermal deformation caused by temperature, a large measurement error of journal center position can occur.
  • Monitoring and Measurement
    Fault Diagnosis of Rolling Bearings Based on Variational Mode Decomposition and Optimized of Support Vector Machine
    JIN Jiangtao, XU Zifei, LI Chun, MIAO Weipao
    2021, 41(3): 214-220. https://doi.org/10.19805/j.cnkij.cspe.2021.03.007
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    Based on the recursive characteristics of empirical mode decomposition (EMD) algorithm, the optimized variational mode decomposition (VMD) algorithm was proposed, so as to establish the multi-modal characteristic matrix combining with the energy entropy method. Finally, the fault diagnosis of rolling bearings was realized using support vector machine technology (OSVM) optimized by the whale algorithm, during which the effectiveness of the proposed algorithm was verified. Results show that the multi-modal characteristic matrix based on VMD algorithm and energy entropy method is superior to the EMD algorithm and energy entropy method in fault discrimination. Compared with the existing methods, accuracy of the proposed VMD-OSVM algorithm is 13.8% and 30% higher under variable load and noise environments, respectively, which reflects the good robustness and generalization performance of the algorithm. Under the same computing resources, the proposed method saves running time, and is more efficient.
    • Environmental Protection Technology and Equipment
  • Environmental Protection Technology and Equipment
    Experimental Study on Simultaneous Removal of NO and SO2 at High Pressure Based on Different Absorbents
    CAI Yuyang, LIU Dunyu, LI Wei, JIN Jing, XU Kailong
    2021, 41(3): 221-226. https://doi.org/10.19805/j.cnkij.cspe.2021.03.008
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    A high-pressure bubble reactor was used to study the mechanism of NO and SO2 synergetic removal process and the effect of CaO and acid (H2SO4 and HNO3) concentration on this process. Results show that there are Raschig and lead chamber mechanisms in the process of synergistic removal; the main N-S compound is HADS(HNO(SO3)22-); the lead chamber reaction will be enhanced by the increase of time, meanwhile, the SO2 absorption efficiency increases while the NOx absorption efficiency decreases. With the increase of acid concentration, the reaction of lead chamber increases, and the absorption efficiency of NOx decreases significantly. Adding CaO into water can enhance the absorption of NOx, and facilitate the formation of NO-3.The initial CaCO3 could be completely transformed into CaSO4·2H2O by reducing the pH of absorption solution to 1.14; by controlling the Ca/S molar ratio to 4.7, 95% SO2-4 in the absorption solution is recovered in the form of CaSO4·2H2O.
  • Environmental Protection Technology and Equipment
    Study and Application on Density Model of White Mud Desulfurization in Coal-fired Power Plants
    MA Shuangchen, FAN Shuaijun, ZHANG Hui, XU Fang, GUO Xiao, LIU Daokuan, FAN Ruimin, CHEN Yongxin, FAN Binbin
    2021, 41(3): 227-235. https://doi.org/10.19805/j.cnkij.cspe.2021.03.009
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    To solve the problems of abnormal operation parameters and difficulties in gypsum dehydration during white mud desulfurization process, the water model, the inorganic salt ion mass concentration model and the density model were established, based on which, the difference between false density and real density of gypsum slurry was studied. The calculating results of the model were corrected by using the total dissolved solids (TDS) mass concentration and the density data of slurry, while coordinated control schemes of TDS mass concentration and density were proposed. Results show that when the TDS mass concentration in gypsum slurry is higher than 80 g/L, the false density of desulfurization system is presented to be a serious deviation, which affects the density control of the desulfurization system and leads to the decrease of the gypsum quality.The proposed coordinated control schemes can provide a reference for desulfurization operation in coal-fired power plants.
    • System Engineering
  • System Engineering
    Cycle Performance Analysis of Packed Bed Cold Energy Storage Tank with Supercritical Compressed Air
    CHEN Mengdong, XU Guizhi, HU Xiao, DENG Zhanfeng, LIAO Zhirong
    2021, 41(3): 236-243. https://doi.org/10.19805/j.cnkij.cspe.2021.03.010
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    Based on the two-dimensional porous medium thermal equilibrium model, the cold charging/discharging cycle of the packed bed cold storage tank was calculated, and the effects of cut-off temperature, inlet mass flow rate and working pressure on the cycle thermal performance of the cold storage tank were analyzed. Results show that with the increase of the cold charging/discharging cut-off factors, thermocline layer reduces, while charging/discharging time and cyclic time increase, and effective capacity ratio increases gradually; with the increase of inlet mass flow, cold charging/discharging time and the cyclic time significantly decrease, but the increase of inlet mass flow have little influence on the temperature and effective capacity ratio of cold storage tank at the cold charging/discharging cut-off time; the increase of working pressure of cold storage tank has little influence on the temperature change of the cold storage tank during cold charging process, but it can significantly shorten the cold discharging time and prolong the time of the low temperature outlet section during cold discharging process.
  • System Engineering
    Research on Coupling Schemes of a Compressed Air Energy Storage System and Thermal Power Unit
    LI Bin, CHEN Jiling, LI Chenxin, CHEN Haisheng, JI Lü
    2021, 41(3): 244-250. https://doi.org/10.19805/j.cnkij.cspe.2021.03.011
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    Aiming at the flexible transformation of thermal power units, coupling schemes of a compressed air energy storage system and thermal power unit were proposed. The system simulation was conducted using Ebsilon software, which was evaluated by heat consumption rate and energy utilization factor. Results show that the optimal coupling scheme is to extract condensate from outlet of the condensate pump in the energy storage stage, which would be sent back to the deaerator after absorbing compression heat. In the energy release stage, a small amount of No. 5 extraction steam is taken, which is used to heat high-pressure air and then sent it back to the No.5 LP heater drain cooler. Working power of the expander can be changed by changing its inlet air temperature and mass flow.
    • Nuclear Technology
  • Nuclear Technology
    Implementation Method of Seismic Response Spectrum Test for Speed Sensor of Reactor Coolant Pump
    GE Lei, LU Xing, DING Duoliang
    2021, 41(3): 251-256. https://doi.org/10.19805/j.cnkij.cspe.2021.03.012
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    To implement the seismic test for speed sensor of reactor coolant pump, an amplifier was designed, for which, frequency response analysis, transient time history analysis and debugging test were carried out. The structure and size of the amplifier were determined by frequency response analysis, and the response spectrum curve in required position of the amplifier was obtained under given input conditions through transient time history analysis, so as to further study the design feasibility of the amplifier. Debugging tests were repeatedly conducted for the amplifier based on transient analysis results and performance parameters of the seismic table, thus to make the test response spectrum in required position be able to envelop the required response spectrum of the amplifier, and finally to complete the seismic response spectrum test for speed sensor of reactor coolant pump.