Power Equipment

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  • 2018 Volume 32 Issue 2
    Published: 15 March 2018
      
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  • Experimental Study on Ash Formation Characteristics of Zhundong Coal in Chemical Looping Combustion
    Ou Zhaowei, Xiao Jun
    2018, 32(2): 75-80.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To study the effects of reaction atmosphere, temperature and the existence of iron ore on ash formation characteristics of Zhundong coal, experimental tests were conducted in a thermogravimetric analyzer. Results show that the mechanical strength of Zhundong coal ash from chemical looping combustion (CLC) is higher than that from direct air combustion, and the larger the coal particle is, the higher the mechanical strength of corresponding coal ash would be. The ash formation rate of Zhundong coal increases with rising temperature, and steam agent is more conducive to the ash formation process compared to CO2 atmosphere; besides, sodium content fixed in ash in CLC process is lower than that in conventional combustion process, especially for the CLC with steam as the gasification agent.
  • Numerical Simulation on Flow and Heat Transfer Characteristics in a Rectangular Channel with Ribs
    Han Huaiyuan, Shen Qiunong
    2018, 32(2): 81-85.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A flow model and a solid model were respectively established for the internal cooling passage with 45-degree ribs installed in the first stage of a gas turbine rotor blade. The effects of above ribs on the flow and heat transfer characteristics in the cooling passage were studied through numerical calculation with the flow model, following which the heat transfer coefficient calculated was introduced into the solid model for further calculation purposes. Results show that the ribs may cause separation and reattachment of the gas flow, and would help to generate transverse flow of the gas, thus enhancing the heat transfer in most area of the wall. The cooling requirements can be satisfied when the Reynolds number at the entrance gets up to 19413.
  • Study on Fault Prediction of a Coal Mill Based on Phase Space Reconstruction and SVR
    Li Dezhong, Yang Liu, Hu Rong, Ren Zilong, Xie Xiaopeng, Xiang Chunbo
    2018, 32(2): 86-89.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem that accurate models are hard to be constructed for coal mills of thermal power plant due to strong coupling characteristics of the multi state variables and complex operating conditions of the coal mill, researches were conducted on status estimation and early fault warning of the coal mill with the operation data of a 320MW unit based on the phase space reconstruction and support vector regression (SVR) method, after which Matlab was applied to verify and analyze the precision of the proposed method. Results show that the prediction method has a high estimation accuracy, which can promptly identify abnormal operations of coal mills, and therefore is applicable in fault diagnosis of auxiliary equipments for thermal power plants.
  • Fuzzy Comprehensive Evaluation for Energy Saving and Emission Reduction of Coal-fired Units Based on Subjective-Objective Weighting Method
    Bai Jianhua, Wei Jianpeng, Liu Jixiang, Xu Fangling, Wang Haisheng
    2018, 32(2): 90-93.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    According to the operation data of 6 coal-fired units in a certain region, a fuzzy comprehensive evaluation system of energy saving and emission reduction was constructed based on the integration of subjective and objective weights by computing the weight of each evaluation index using expert investigation approach and entropy weight method, so as to evaluate the performance of the 6 units in energy saving and emission reduction. The evaluated results agree well with actual measurements, proving the evaluation method to be effective, which may serve as a reference for fine management of related coal-fired power plants, and for economic dispatch of power network considering energy saving and emission reduction.
  • Experimental Study on the Shape of Ash Dampers above an Economizer Hopper
    Deng Huaiming, Chen Hongwei, Zhao Chao, Zhang Qian
    2018, 32(2): 94-98.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To explore the effect of ash dampers above an economizer hopper on the fly ash trapping performance, a 1:20 cold state test rig, referring to a 600 MW coal-fired boiler, was built by using organic glass to conduct experimental tests. Results show that both the plate damper and airfoil damper can improve the ash collection efficiency of the economizer hopper, however, the plate damper may cause higher pressure loss, while the airfoil damper could obviously improve the ash collection efficiency with little increase in pressure loss. This may serve as a reference for initial dust removal from ash hoppers in coal-fired power plants.
  • Analysis on Energy Saving and Emission Reduction of Cold End Exhaust System in Direct Air-cooling Units
    Li Yuanbo, Zhao Jian, Niu Quanxing, Qin Xiaoyan
    2018, 32(2): 99-103.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An analysis was conducted on the advantages and disadvantages of energy saving and emission reduction technologies for cold end exhaust system of domestic direct air-cooling units. Results show that the exhaust steam application technology has to be improved in summer. But it presents remarkable effects in winter, in which the waste heat recovery technologies by the way of heating network condenser and steam jet pump are proved to be the most advanced ones, featured by low investment, and high energy saving and emission reduction effects.
  • Selection and Layout of Heating Surfaces in a Vertical Type Heat Recovery Steam Generator
    Cheng Zhi, Gao Lingfeng, He Haihua
    2018, 32(2): 104-107.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on an introduction to the basic composition of a vertical type heat recovery steam generator (HRSG), 4 selection schemes were proposed for the heating surfaces, which were subsequently compared from following aspects, such as the structure, the circulation ratio and the steel consumption, etc. An optimal scheme was finally obtained after some improvements were made on the structure of related heating surfaces.
  • Numerical Simulation on Low NOx Combustion of Bituminous Coal in a Swirl-opposed Firing Boiler
    Wang Songhao
    2018, 32(2): 108-113.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To study the combustion characteristics of bituminous coal in swirl-opposed firing boilers, Fluent software was used to simulate the combustion of bituminous coal in a 396 MW swirl-opposed firing boiler, after which, analyses were conducted on the velocity field, temperature field, particle trajectory and the distribution of O2, CO2 and NO. Results show that there are two obvious vortex regions in the lower part of the furnace; both the internal and external secondary air flow in the pattern of swirling in the main swirl burner, which produce high temperature flue gas recirculation zone in the swirl burner. The average content of O2 and CO2 presents complementary relationship along the furnace height.
  • Numerical Study on Elimination of White Smoke from Coal-fired Power Plant Chimneys
    Jia Minghua, Xu Peng, Li Bin, Wu Qilong, Zhang Yong
    2018, 32(2): 114-117.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To eliminate the white smoke phenomenon in a coal-fired power plant, the physical process of white smoke formation was analyzed after flue gas leaving chimney. Taking a certain power unit as an example for numerical calculation, the effects of flue gas saturation temperature and environmental condition on the formation of white smoke were studied. Results show that lower saturation temperature is helpful to the elimination of chimney plume.
  • Selection and Calculation on Elastic Support of Pitch Control Cabinet for Wind Turbines
    Li Hongmei, Wang Bing
    2018, 32(2): 118-121.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Appropriately choosing the elastic support for installation of pitch cabinet is to guarantee the safety of the cabinet body and cabinet internal parts in the wind turbine. The elastic support for installation of pitch cabinet can be reasonably selected through analysis on the installation conditions, the hub load capacity, the property of the elastic support and the resonance characteristics of the wind turbine, etc.
  • Study on Hardfacing Procedure for GH2132 Superalloy with Cobalt Alloy
    Chen Daofeng, Ren Xiao, Zhong Chengshan
    2018, 32(2): 122-125.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Cobalt alloy was deposited on the surface of GH2132 superalloy by plasma transferred arc hardfacing technology, after which the welded metal was examined in the way of dye penetrant inspection, visual examination, dilution analysis, microstructure examination and microhardness testing. Results show that the quality of the hardfacing layer is relatively good, which reaches quality level 4 completely after grinding. Besides, the results of dilution analysis and microhardness testing prove these two indexes to agree well with relevant technical requirements.
  • Improvement on Excitation System of Electric Generator in a 1 000 MW Nuclear Power Plant
    Yu Qianjun
    2018, 32(2): 126-129.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An analysis was conducted on several problems occurring in commissioning and operation of the generator excitation system in a 1 000 MW nuclear unit, such as the failure of excitation caused by unreasonable flashing logic and loop parameters, the field breaker tripping during high level step resulted from no continuous current, no redundancy power supply designed for the regulator, and the malfunction of its rotor grounding, measuring and brush-lifting device, etc., following which corresponding countermeasures were put forward and taken, and subsequently the reliability, availability and stability of relevant facilities in the power plant were improved. This may serve as a reference for troubleshooting of similar domestic units.
  • Improvement on Operation Reliability of Industrial Pumps for a Large-scale Fossil-fired Power Plant
    Wang Jihua, Zhou Quan, Lü Bin, Chen Yongkang
    2018, 32(2): 130-134.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of unreasonable power configuration of industrial water pump system in a 2×1 050 MW fossil-fired power plant in the stage of engineering design, five schemes of technological retrofit were analyzed in terms of operational reliability, efficiency, maintenance safety and retrofit economy, etc., such as adding an inverter control cabin for industrial water pump C, connecting industrial water pump B to the PC of chemical water treatment system, instead of three industrial water pumps controlled by one inverter, and so on. Results show that the retrofit is safe and reliable, which may serve as a reference for treatment of similar problems.
  • Diagnosis and Treatment on Vibration Faults Occurring in HP-IP Rotor of a 300 MW Heating Unit
    Wang Fengliang
    2018, 32(2): 135-138.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of high vibration fault occurring at the first order critical speed in HP-IP rotor during start-up of a 300 MW heating unit after retrofit on its brush seal, an analysis was conducted on the vibration characteristics and causes, and subsequently corresponding countermeasures were put forward and taken, after which the vibration fault is eliminated, with safety and stable operation of the unit obtained, under the premise of securing the safety of the HP-IP rotor.
  • Cause Analysis of Steam Temperature Oscillation in a 1 000 MW Double Reheat Unit
    Hu Zunmin
    2018, 32(2): 139-143.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By analyzing the steam temperature oscillation occurring in a 1 000 MW double reheat unit, the problem was found to be caused by the shock in primary air system due to time lag of the primary air flow from the coal mill, which subsequently resulted in oscillation of the steam temperature and pressure in the whole unit. Meanwhile, an introduction was presented to the interaction and mutual effects of the primary air system and the whole coordinated control system.
  • Error Analysis and Calibration of CS2024 Coal Feeders
    Liu Xueyong, Wang Dikai, Wang Zhifang
    2018, 32(2): 144-147.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    According to the weighing principle of coal feeder, three causes leading to the error of coal feeder were analyzed, such as external factor, mechanical factor and measurement factor, for which detailed solutions were given to provide a guarantee for the calibration accuracy of coal feeder. By comparing the three common calibration methods, the method of hanging weight not only saves a lot of manpower and material resources, but also has high measuring accuracy, thus is worthy of being popularized and applied for other power plants using same type of coal feeders.
  • Fault Analysis of a Rotor Overvoltage Detection Circuit in an Excitation System
    Li Chengshuai, Pu Xiaojun, Wu Fangyuan, Luo Haibing
    2018, 32(2): 148-152.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the abnormal outage problem of a unit caused the faulty rotor overvoltage detection circuit of its Unitrol 6080 excitation regulator, an analysis and field verification were conducted on the hardware circuit and software logic, and subsequently, the problem was found to be caused by over-current bonding of the magnetic switch auxiliary contacts and design defects of the hardware circuit, to which, some preventive measures were put forward.