Power Equipment

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  • 2015 Volume 29 Issue 4
    Published: 15 July 2015
      
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  • Retrofit of a Wflame Boiler for Burning Bituminous Coal
    Qiu Jihua, Huang Yiqun, Wang Li, Zhang Xiaoping, Xiong Jinhua
    2015, 29(4): 237.
    Abstract ( )   Knowledge map   Save
    A 300MW Wflame boiler was retrofitted from originally burning anthracite into burning bituminous coal by adjusting the area of refractory belt, controlling the outlet flue gas temperature within the original design range, canceling the exhaust gas nozzle of burners, increasing the primary air speed and air volume to facilitate ignition and combustion of bituminous coal, improving the safety of the coal pulverizing system to ensure that it can operate safely. Retrofit results show that when the bituminous coal of w(Vdaf)= 25%~35% and Qnet,ar=20〖CD*5/9〗22 MJ/kg is burned, the temperature and pressure of both the main steam and reheat steam as well as the unit power output can all meet original design requirements of the boiler, in which case, the pulverizing system will be able to operate safely for a long time, and the thermal efficiency of boiler would be increased by 2%, the NOx emission would be lowered to be below 400 mg/m3, with no obvious slagging and without burnout burners in the furnace.
  • Experimental Study on Thermal Deviation of Water Wall Tubefor Supercriticalpressure Wflame Boilers
    Yang Yong, Li Jianping， Zhou Wentai, Yang Yao, He Xiang
    2015, 29(4): 242.
    Abstract ( )   Knowledge map   Save
    Taking the 600 MW supercriticalpressure Wflame boiler as an example, measurement and calculation were carried out on the thermal deviation of water wall tube under varying conditions. Results show that the thermal deviation factor tends to be 1 during startup process, indicating uniform distribution of medium temperature at water wall outlet; under subcriticalpressure conditions, the selfcompensating characteristics of water wall tube are relatively sound, with heat absorption deviation decreasing gradually, which under supercriticalpressure conditions, is rather large and greater on the upper part than on the lower part of the water wall tube.
  • Experimental Study on Blended Coal Combustionof Large Power Plant Boilers
    Liu Fasheng, Tan Zixing, Gui Liangming, Ao Guanghui, Cheng Wenfeng, Shu Kaitai, Chen Linguo
    2015, 29(4): 248.
    Abstract ( )   Knowledge map   Save
    To solve the problems occurring in a 640 MW boiler caused by burning nondesigned coal for a long period that had led to great impact on the safe and economical operation of the boiler, elemental analysis, thermogravimetric analysis and classification were made for various kinds of coal commonlyused in the power plant, after which the coal types to be involved in the research on blended coal combustion were determined. With three characteristic load points selected and through conducting hot tests with coal mixtures in different blending proportions under different feeding modes, an optimal blended coal combustion scheme and coal feeding mode were obtained for the boiler, thus effectively enhancing the safety and economic efficiency of the boiler unit.
  • Application of Artificial Intelligence Technology in Modeling of Reheat Steam Temperature
    Tang Zhibing, Wang Mingchun, Tao Chengfei,Liu Jinquan
    2015, 29(4): 252.
    Abstract ( )   Knowledge map   Save
    Reheat steam temperatures on both sides of the reheater in a power plant were modeled using the radial basis function (RBF) in neural networks and the algorithm of support vector machine (SVM), after which the calculation results were analyzed. Results show that both the artificial intelligence technologies have the features of rapid modeling and high precision. However, in terms of accuracy, RBF algorithm is superior to SVM algorithm, because SVM algorithm only relies on cross validation in optimization of parameters.
  • Study on Calculation Method for Abrasive Property Parameters of Coal
    Huang Yong, Wang Chunmin, Wang Meng, Zhang Jiling
    2015, 29(4): 256.
    Abstract ( )   Knowledge map   Save
    An introduction is being presented to the testing and measurement way for abrasive properties of coal, together with an analysis on the calculation methods according to the relationship between abrasive property and chemical composition of the coal, so as to obtain the degree of correlation between various calculation methods and the impingement abrasion index Ke. Results show that there is a high degree of linear correlation between mineral content obtained by calculation and the Ke, and the former one can directly be used to determine the abrasive property of coal if the value of Ke can t be acquired, thus guiding the model selection of pulverizers.
  • Analysis on Cooling Tower Parameters under Variable Working Conditions
    Huang Ruguang, Xiang Molin, Li Xia
    2015, 29(4): 261.
    Abstract ( )   Knowledge map   Save
    With Merkel formula, the characteristics of a cooling tower were studied under variable working conditions, with corresponding characteristic curves plotted. Analysis and calculation results show that the outlet water temperature of cooling tower is not sensitive to the change of dry bulb temperature, but is more sensitive to the change of wet bulb temperature and atmospheric pressure; in addition, the outlet water temperature of cooling tower is more sensitive to the change of ventilation rate than to the change of the cooling water flow rate.
  • Technical Measures for Anti Cavitation of Oil Ejectors
    Liu Xiaofeng
    2015, 29(4): 264.
    Abstract ( )   Knowledge map   Save
    For the cavitation problems encountered by oil ejectors for steam turbine of a power plant, the situation of current use of oil ejectors was investigated and analyzed, while causes leading to the problems and possible potential harms were studied, to which comprehensive measures were put forward.
  • Optimization on Sootblowing Mode of a Coalfired Boiler
    Wang Xiaohui, Zhang Jie
    2015, 29(4): 268.
    Abstract ( )   Knowledge map   Save
    By comparing the effects of fixed sootblowing and selective sootblowing mode on safety and economy of a 600 MW coalfired boiler, the option of selective sootblowing mode was recommended based on analysis of relevant test data. It has been found that, to reduce the energy consumption of the boiler, different sootblowing periods are to be adopted according to actual situation of various heating surfaces.
  • Cause Analysis and Countermeasures for High Exhaust Gas Temperature of a Bituminous Coalfired Wflame Boiler
    Cheng Yongfeng
    2015, 29(4): 273.
    Abstract ( )   Knowledge map   Save
    To reduce the exhaust gas temperature of a Wflame boiler changing from burning anthracite into burning bituminous coal, an analysis was conducted to the causes leading to the temperature rise of exhaust gas, and subsequently corresponding countermeasures were proposed and taken. Results show that by increasing outlet air temperature of the pulverizer from 80 ℃ to 85 ℃ and by strengthening soot blowing on related heating surfaces, the exhaust gas temperature has been lowered by 4~6 K as expected.
  • Analysis and Treatment of Steamexcited Vibration Faultfor a Steam Turbine Unit
    Yang Dan, Fu Xingjun
    2015, 29(4): 276.
    Abstract ( )   Knowledge map   Save
    To solve the problem of lowfrequency vibration existing in the high/mediumpressure rotor of a 330 MW unit caused by steamexcited vibration found through control test on the governing valve, following countermeasures are proposed, such as adjusting the bearing elevation and the flow path clearance during overhaul, based on the mechanism and characteristics of the steamexcited vibration as well as the actual situation. By taking above countermeasures, the low frequency vibration of steam turbine is suppressed, ensuring the safe operation of the unit.
  • Optimization and Energy Saving for a 600 MW Supercritical Thermal Power Unit during Startup
    Xi Chengchao
    2015, 29(4): 279.
    Abstract ( )   Knowledge map   Save
    To solve the problem caused by frequent startup/shutdown of a 600 MW supercritical thermal power unit, corresponding measures are proposed for optimization and energy saving of the unit during startup process, so as to shorten the startup time under the premise the unit safety is improved.
  • Retrofit on Leakage Control System of Rotary Air Preheaters
    Ma Shisong, Li Jianrong, Song Yan
    2015, 29(4): 284.
    Abstract ( )   Knowledge map   Save
    An introduction is being presented to the working principle of leakage control system (LCS) for air preheater of a 1000 MW unit, while problems existing in operation of the LCS are analyzed, to which comprehensive measures are proposed and verified. It has been found that after retrofit, the LCS is able to run well, with reduced air leakage rate, achieving the energysaving purposes.
  • Leakage Analysis of Hightemperature Superheaters
    Chen Xun, Zhou Liqin
    2015, 29(4): 288.
    Abstract ( )   Knowledge map   Save
    The reasons of leakage found in the hightemperature superheater of a circulating fluidized bed boiler during boiling out were examined by scanning electron microscope, energy spectrum analysis and microscopic crack analysis. Results show that the breaking of superheater elbow is of the stress corrosion kind, which is caused by combined action of chloride ion and residual tensile stress.
  • Feasibility Analysis on Power Generation with VAM
    Zhang Zhihong, Yan Naiqiang
    2015, 29(4): 291.
    Abstract ( )   Knowledge map   Save
    An introduction is being presented to principles and process flow of the power generation technology with ventilation air methane (VAM), together with an analysis on economic feasibility of corresponding power generation projects using VAM, which may serve as a reference for similar domestic projects.
  • Application of WGGH in Flue Gas Desulfurization System of Power Plants
    Tong Jialin, Fang Lei, Zheng Jianping, Zhang Ming
    2015, 29(4): 294.
    Abstract ( )   Knowledge map   Save
    To overcome the deficiencies of high pressure difference existing in the gasgas heater (GGH) that is easy to be blocked, the technology of water medium heat pipe gasgas heater (WGGH) was proposed. Taking an ultra supercritical power unit as an example, technical advantages and disadvantages were compared for the unit before and after installation of WGGH. Results show that compared with GGH, WGGH can help to lower the auxiliary power consumption rate and improve the reliability of flue gas desulfurization system, thus ensuring the economy and social benefit of the unit.
  • Cause Analysis on High Differential Pressure of GGH in Desulfurization Unit of a Thermal Power Unit
    Li Xingmin
    2015, 29(4): 297.
    Abstract ( )   Knowledge map   Save
    To solve the problem of high differential pressure existing in rotary regenerative gasgas heater (GGH) of a power plant, which had greatly raised the resistance in the gasair system and subsequently affected the normal operation of the unit, an analysis was carried out to the GGH operation conditions, so as to study the blockage reasons and obtain a solution for the high differential pressure of GGH.
  • Study on Low NOx Emission of 1 036 MW Coalfired Boilers
    Cai Chun, Li Peipeng, Zhao Yumin, Feng Tingyou
    2015, 29(4): 300.
    Abstract ( )   Knowledge map   Save
    Taking 4 1036MW units in a power plant as examples, detailed analysis was conducted to the NOx emission characteristics of the coalfired boilers from the aspects of infurnace combustion and gas treatment technology, etc., so as to determine the influencing factors and degrees, and to put forward key control points at each stage and the matters needing attention. It has been found that the NOx emission can be kept to be below 40 mg/m3 in the longterm operation of boilers. This may serve as a reference for energy saving and environmental protection of relevant power plants.
  • Analysis and Countermeasures for Abnormal Accidentsin Denitrification System for Ammonia Supply
    Hu Lichuan, Xu Yuqun, Chen Yuzhong, Zeng Xiaomin
    2015, 29(4): 304.
    Abstract ( )   Knowledge map   Save
    An introduction is being presented to the principle of selective catalytic reduction denitrification technology and to the equipment adopted in the denitrification system for ammonia supply, with the protection logic of main facilities analyzed, while corresponding countermeasures are proposed for abnormal accidents occurring in operation of the denitrification system. In addition, some proposals are suggested for operation and control of the equipment, so as to secure safety and stable operation of the ammonia supply system.
  • Finite Element Analysis of Wind Turbine Blades Based on UG
    Pan Cong, Li Jiaqi
    2015, 29(4): 308.
    Abstract ( )   Knowledge map   Save
    A method was proposed for finite element analysis of wind turbine blades, with which the blades were modeled and calculated using UG software. Results show that both the strength and stiffness of the blade model are high enough to meet the requirements of actual application.