Power Equipment

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  • 2019 Volume 33 Issue 4
    Published: 15 July 2019
      
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  • Simulation Research on Flow-accelerated Corrosion of 90° Elbows in Power Plants
    Lin Tong, Zhou Keyi, Si Xiaodong
    2019, 33(4): 223-228.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To obtain the flow field distribution in 90° elbows of power plants, and to study the correlation between the corrosion behavior and the fluid flow dynamics, numerical simulations were conducted on the flow-accelerated corrosion (FAC) in the elbows under actual operation conditions using ANSYS software. Results show that the corrosion rate on the inner side of elbow is higher than that on the outer side, and the maximum corrosion rate occurs on the innermost side, while the minimum corrosion rate appears on the outermost side.
  • Numerical Simulation on the Effects of Slotted Fin on Heat-transfer Performance of the Finned Heat Exchangers
    Zhang Meifeng, Jia Shixun, He Xuehong
    2019, 33(4): 229-232.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Three-dimensional simulations were conducted on slotted and non-slotted fins using FLUENT software to study their heat-transfer performance by analyzing the temperature field and pressure field. Results show that with the rise of air velocity, the heat-transfer rate and pressure loss of both the fins increase; at constant air velocity, the slotted fin has higher heat-transfer rate and greater pressure loss. The comprehensive heat-transfer performance of tubes with slotted fin is better than that with non-slotted fin.
  • A Comparative Study on Slagging and Fouling Characteristics of the Coal from Two Major Zhundong Mining Areas
    Yang Hailiang
    2019, 33(4): 233-236.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Combustion experiments were conducted on the Zhundong coal respectively from Wucaiwan mining area and Jiangjunmiao mining area to study their slagging and fouling characteristics. Results show that the content of Ca in Wucaiwan coal ash is relatively high, and the coal has high tendency of slagging; whereas the content of Fe in Jiangjunmiao coal ash is relatively high, and the coal has high tendency of fouling. Above two kinds of coal should be treated differently in actual applications.
  • Study on Mercury Speciation and Distribution during Oxygen-enriched Combustion of Coal in a Fluidized Bed Boiler
    Fang Bo, Yao Xudong
    2019, 33(4): 237-241.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To study the effects of primary air and different additives (limestone or limestone-kaolin mixture) on the mercury speciation in flue gas and the mercury enrichment in fly ash or bottom slag, combustion experiments were conducted in a fluidized bed test rig respectively under air and oxygen-enriched atmosphere. Results show that under oxygen-enriched atmosphere, with the rise of primary air rate, the mercury oxidation is promoted, while the enrichment factor of mercury in fly ash increases and that in bottom slag reduces. The addition of limestone improves the mercury oxidation rate. The addition of both the additives, limestone and limestone-kaolin mixture, reduce the gaseous mercury concentration in flue gas, and increase the mercury enrichment factors in fly ash and bottom slag significantly.
  • Numerical Simulation on the Evaporation Process of Desulfurization Wastewater in a Flue Duct
    Lu Qiliang, Zhang Juan, Chen Wei, Zhao Liang, Liu Pingyuan, Huang Xiaoming, Yuan Zhulin, Min Haili
    2019, 33(4): 242-247,251.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the self-developed model, numerical simulations were conducted on the evaporation process of desulfurization wastewater in the flue duct of a laboratory apparatus and a typical 660 MW supercritical unit. Results show that the data calculated based on the model agree well with experimental data, indicating high accuracy of the model. The temperature of flue gas has a great influence on the evaporation of desulfurization wastewater, and the increase of temperature will accelerate the evaporation. The atomizing angle has less influence on the evaporation, but the increase of atomizing angle will aggravate the ash accumulation. Among non-uniform particles, the droplets of large sizes have a great influence on the evaporation, which take long time to evaporate completely.
  • Effects of Flue Gas Velocity on PM10 Removal by Wet Electrostatic Precipitator
    Zhao Liang, Liu Pingyuan
    2019, 33(4): 248-251.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking the vertical tube-type wet electrostatic precipitator equipped in a coal-fired power unit as an object of study, the effects of flue gas velocity on the removal of fine particulate matter (PM10) were researched by changing the flue gas flow rate through adjusting the opening of the flue gas bypass valve. Results show that with the decrease of flue gas velocity, the removal efficiency of PM10 could be improved by wet electrostatic precipitator.
  • Fault Analysis for the SCR De-NOx System in a Thermal Power Plant and Corresponding Solutions
    Zhang Feng
    2019, 33(4): 252-256.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To lower the frequency of SCR de-NOx system malfunctions, an analysis was conducted on the reasons leading to the faults, with effective measures put forward. Results show that the safe and economical operation of an SCR de-NOx system in thermal power plant could be guaranteed when following measures are taken, like dredging the ammonia supply pipes, optimizing the automatic adjustment logic and improving the evenness of ammonia injection, etc.
  • Control Scheme for Automatic Startup of an Air-Gas System in a Thermal Power Plant
    Ye Funan, Zhuang Wei
    2019, 33(4): 257-262.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Control schemes for automatic startup of a boiler air-gas system were designed based on sequence and analog micro control system to start up and shut down the air preheater and 6 big air fans in sequence, so as to achieve fast establishment of air duct and realize automatic retreat of the forced-draft fan, induced-draft fan and primary air fan, thus greatly shortening the startup time of the air-gas system and reducing the operating intensity of operators. It has been found that in the automatic control scheme, all the parameters are superior to that in manual operation mode.
  • Analysis on the Self-tuning Control Strategy of an Exhaust Heat-supply Unit
    Jiang Qingchen, You Zhiwei, Yang Jianming
    2019, 33(4): 263-267,277.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking the two-stage CC100-8.83/4.12/1.47 exhaust heat-supply unit as an object of study, a dynamic simulator and a self-tuning algorithm were developed based on LabVIEW software platform, while single-and double-stage off-design experiments were conducted. Results show that the self-tuning control strategy could keep the static deviation of electric power within 1.2%, and that of pressure at extraction point of the heat-supply system within 1%, simultaneously with fast dynamic response, small overshoot and superior regulating effect.
  • Design and Application of Sectional Flue Gas Coolers
    Guo Bochun, Lai Haibing, Xiao Sheng
    2019, 33(4): 268-272.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of high exhaust gas temperature of a coal-fired boiler, a new scheme of sectional type flue gas cooler was designed. Taking the retrofit on a 630 MW power unit by adding flue gas cooler as an example, where the exhaust gas temperature was controlled by the section of low-temperature flue gas cooler, and the inlet temperature of electrostatic precipitator was controlled by the section of high-temperature flue gas cooler. Results show that after retrofit, the exhaust gas temperature could be controlled effectively, while the boiler efficiency be improved, which therefore may serve as a reference for retrofit of similar power units.
  • Selection of Domestic Three-way Valves for Single Stream High Pressure Heaters
    Zhang Shiming, Gu Yong, Yan Zhe
    2019, 33(4): 273-277.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    According to the parameter characteristics of 1000 MW double reheat units, and based on analysis results of faults occurring in the three-way valves for high pressure (HP) heaters during operation and maintenance, an introduction was presented on the selection schemes of domestic three-way valves. By comparing the domestic three-way valves with imported ones, the application of domestic HP heater three-way valves is proved to be feasible, technically reliable and economical.
  • Optimization Retrofit on Heat Supply Modes of Heating Units for Deep Peak-load Regulation
    Tong Jialin, Wu Ruikang, Li Jian, Lü Hongkun
    2019, 33(4): 278-281,292.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An optimization retrofit was carried out on the heat supply mode of heating units for deep peak-load regulation, while an economic analysis was performed on the unit by extracting the steam from different points. Results show that under low load conditions, all the three retrofit schemes with steam extracted respectively from main steam pipe, cold reheat steam pipe and hot reheat steam pipe could satisfy the requirements of heating steam parameters. At 40% THA load, the highest economy of heat supply appears in the scheme with steam extracted from cold reheat steam pipe; whereas at 30% THA load, the economy of heat supply is different between main steam mode and cold reheat steam mode under different heating steam flows. With the reduction of unit load, the advantage of heat supply becomes more obvious in the main steam mode.
  • Application of No-packing Spray Cooling Tower in Large Thermal Power Units
    Wu Chenggang
    2019, 33(4): 282-284.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A comparative analysis was conducted on technical features of packing and no-packing spray cooling tower commonly adopted for auxiliary facilities of large thermal power units, while an introduction was made to the working principle of no-packing spray cooling tower, together with a calculation on its energy-saving effectiveness. Results show that, compared with traditional packing spray cooling tower, the application of no-packing spray cooling tower could reduce the operation and maintenance cost, and improve the operation reliability of relevant facilities simultaneously.
  • Cause Analysis of Tube Wall Overheating during Low-load Operation of a 300 MW Boiler
    Rui Wenming, Wei Jianpeng, Niu Shibin
    2019, 33(4): 285-288,292.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To overcome the deformation, overheating and tube burst failures occurring in boiler superheater tubes during low-load operation of a unit, analyses were conducted on the tube material, such as chemical composition, mechanical property and metallographic microstructure, etc., following which, corresponding countermeasures were put forward for low-load operation, variable load operation and shutdown period of the unit. Above failures were basically avoided after implementation of the countermeasures.
  • Application of Forced Fast Cooling Technology in Domestic 660 MW Steam Turbines
    Zhang Lei, Fan Xilin, Liu Shuyuan, Chen Shaolong
    2019, 33(4): 289-292.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of small cooling rate of metallic areas at governing stage and in turbine cylinder during shutdown of domestic 660 MW supercritical steam turbine units, a forced fast cooling technology is presented by using the waste heat of boiler. The technology has been successfully applied in a 660 MW supercritical steam turbine, which could not only avoid the thermal shock to the rotor and cylinder without increasing the life loss of steam turbine, but also greatly shorten the waiting time for overhaul to improve the availability of the unit.
  • Optimization on Cold Start-up Rotation-impulsing Parameters of a 1 000 MW Double Reheat Steam Turbine
    Xu Jiang, Xue Xiaoyu
    2019, 33(4): 293-296.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of severe vibration occurring in the medium-pressure regulating valve during low-speed warm-up process in the start-up of a double reheat steam turbine, analysis and optimization were conducted on the steam parameters for cold start-up of the unit. Better effectiveness could be obtained for the unit by lowering the steam parameters, when both the warm-up and the grid-connection time are reduced, while the operation safety and stability of the unit are improved.