Power Equipment

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  • 2017 Volume 31 Issue 6
    Published: 15 November 2017
      
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  • Study on Interference Effects between First-and Second-Stage Abnormal Blades of an Axial Flow Fan
    Feng Yao, Dong Yunshan, Si Fengqi, Bai Delong, Xie Guanyu
    2017, 31(6): 383-389.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of abnormal drifts of installation angles existing in the first-and second-stage blades of a SAF36-25-2 two-stage adjustable axial-flow induced-draft fan, Fluent software was applied to research the change rules of fan performance parameters and the interference relation of abnormal blades in the first-and second-stage. Results show that the overall fan performance at an abnormal drift angle of △β2=+8° in the second impeller is better than that at △β2=-8°. Keeping the △β2 unchanged, when the abnormal drift angle in the first impeller changes from -12° to +12°, the fan performance increases first and then decreases, and both the fan pressure and efficiency show the most evident deterioration in the whole flow range at △β1=-12°, whereas the abnormal blade has the least effect on the fan performance at △β1=+8°. With the increment of drift angle, the interference effects of the first-stage abnormal blade on the performance of the second-stage impeller would be enhanced.
  • Experimental Study on Reactivity of an Iron Ore Oxygen Carrier Decorated by K-Na
    Ou Zhaowei, Xiao Jun
    2017, 31(6): 390-396.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Experiments on chemical looping combustion were conducted in a batch fluidized bed reactor with iron ore oxygen carrier decorated by K-Na based on wet impregnation method, so as to study the effects of K-Na ratio, reaction temperature and the number of cycles on the performance of the oxygen carrier. Results indicate that the CO cumulative conversion rate in the case of using iron ore oxygen carrier decorated by K-Na is obviously higher than that using natural iron ore; reaction temperature has a significant influence on the reactivity of the oxygen carrier; both K and Na have a steady effect on the reactivity of the decorated iron ore in cyclic process, and the reactivity of both 5Na1K-Fe and 1Na5K-Fe is obviously higher than that of 3Na3K-Fe.
  • Heat Loss Calculation and Analysis for a Regenerative System with ESC Based on Improved Flow Distribution Method
    Lin Runda
    2017, 31(6): 397-402.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To accurately calculate the heat loss of a regenerative system with external steam cooler (ESC), the matrix structure used in flow distribution method was improved. Results show that the calculated heat loss of the unit is 7 254.58 kJ/(kW·h) under THA operating condition without consideration of the auxiliary steam loss and with consideration of the enthalpy rise in feed water pump, when the cycle efficiency reaches 50.88%. The heat loss has been reduced by about 15.29 kJ/(kW·h) compared with the design without ESC. The improved method helps to solve the problem in calculation of heat flows at different levels, indicating stronger versatility of the improved flow distribution method.
  • Application Study on an Adaptive Control System of Primary Air Pressure in 1 000 MW Unit
    Lin Dianpeng, Wang Chuhong, Li Daji, Jiang Yong
    2017, 31(6): 403-406.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To reduce the power consumption of primary air fans, an adaptive control system of primary air pressure was designed and applied by adding an independent adaptive primary air pressure bias circuit based on the original setting value, thus gradually reducing the primary air pressure and the power consumption of primary air fans under the premise of ensuring the safe operation of the coal pulverizing system. Meanwhile both the air preheater leakage rate and the power consumption of induced draft fans drop accordingly due to the reduction of primary air pressure, resulting in obvious energy saving effect.
  • Economic Analysis of an Integrated Solar Combined Cycle
    Bing Yini, Wang Jun, Liu Tingting
    2017, 31(6): 407-410.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The advantages of an integrated solar combined cycle (ISCC) system were analyzed by comparing it with an independent solar energy generation (SEG) power plant and a conventional gas turbine combined cycle (GTCC) unit. Results show that compared with GTCC unit, the ISCC system can effectively reduce the fuel gas consumption and CO2 emission, and its economic index is obviously higher than that of a SEG power plant.
  • Application of Nickel-based Alloy Cladding Technology in Manufacture of Nuclear Power Equipment
    Li Shuangyan, Zhang Maolong
    2017, 31(6): 411-415.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A comparative analysis was conducted on four different cladding technologies for nuclear steam generator with tube-tubesheet joints from the aspects of welding technology, welding equipment, welding consumables and welding parameters. Results show that the dual-hot wires gas-metal plasma arc cladding technology is prevailing in the welding of nickel-based alloy tube-tubesheet joints, which can be used in actual cladding of nuclear power equipment products made of Inconel 690 nickel-based alloy.
  • Cause Analysis and Treatment on Long Flushing Period of an AP1000 Lubricating Oil System
    Zhao Zhengqing, Luo Jijiang
    2017, 31(6): 416-419.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the flushing status in lubricating oil system of an AP1000 nuclear power turbo-generator unit, together with an analysis on factors influencing the flushing performance, and subsequently corresponding countermeasures are proposed, which may serve as a reference for flushing in lubricating oil system of similar units.
  • Structure Optimization of a Pump Sump in Circulating Water System of Nuclear Power Plant
    Nie Xiaoqi, Ye Xuemin, Li Daran, Cao Youqun, Zhang Yingying
    2017, 31(6): 420-425.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By control variable method, an adjustment of simulated structural parameters was carried out for the pump sump of a nuclear power plant, after which some parameter ranges were recommended for the sump. Above structural parameters of the pump sump were proved to be rational by numerical simulation.
  • Economic Analysis of a Dewatering, Thermal Drying and Incineration System for Municipal Sludge
    Jiang Zixiao, Chen Xiaoping, Yang Xujun, Song Lian, Zhu Ge, Ge Shifu
    2017, 31(6): 426-432.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on economic analysis of a dewatering, thermal drying and incineration system with a dealing capacity of 250 t/d for municipal sludge, the effects of following factors on the investment cost, operation cost and the system efficiency were studied, such as the dry basis calorific value of original sludge, the moisture content of deeply or thermally dried sludge, and so on, after which, an optimal scheme was obtained. Results show that the dry basis calorific value of sludge has the greatest influence on the investment cost of the system; the system efficiency decreases rapidly when the amount of steam produced by the incineration system cannot meet the requirement of sludge thermal drying.
  • Application of Non-uniform Ammonia Injection System in Hybrid SNCR+SCR Denitrification Process
    Liang Cunjing, Zhang Zhancheng, Huang Guoqiang
    2017, 31(6): 433-437.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To overcome the obvious shortcomings of uneven NH3-NOx distribution in selective non-catalytic reduction (SNCR) flue gas, and taking full advantages of SNCR system that does not require catalyst during denitrification, a hybrid SNCR+SCR denitrification process was proposed by adding a non-uniform ammonia injection system. The advantages and disadvantages of urea hydrolysis and pyrolysis for ammonia production were compared and analyzed. The ammonia injection grid was optimized by experimental study, with focus on the applicability of the ammonia injection system. The effect of hybrid urea hydrolysis for ammonia and SCR non-uniform ammonia injection system in industrial application was analyzed. Results show that the the NOx removal efficiency could be significantly improved by coupling the urea hydrolysis for ammonia with the hybrid SNCR+SCR denitrification system, thus solving the problem of uneven NH3-NOx distribution.
  • Cause Analysis and Countermeasures for Vibration of a Low-temperature Economizer and MGGH
    Li Jian, Qin Songbo
    2017, 31(6): 438-441.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the vibration problems occurring in low-temperature economizer and MGGH of a thermal power plant, deep testing and analysis were conducted. Results show that the vibration is found to be caused by the resonance due to the shedding frequency of Karman vortex resulted from too high or uneven flue gas flow being approximate to the frequency of standing acoustic waves of the flue duct. Above problems could be solved by adding shock plates and baffle plates at appropriate locations.
  • Research on RB Test and Control Strategy of an Ultra Supercritical Double Reheat Unit
    Zhang Tianhai, Yu Guoqiang, Shu Jianjun, Guan Shipian, Hu Zunmin
    2017, 31(6): 442-447.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To satisfy the special requirement of runback (RB) function in double reheat thermal power units, an introduction was presented to the meaning and classification of RB. Based on the dynamic process of RB test for a domestic 1 000 MW ultra supercritical double reheat unit, an analysis was conducted on key points and difficulties of RB control in the double reheat unit, after which an optimization was carried out on the control strategy. Results show that the actions of RB logic are proved to be correct; the over-temperature problem occurring in the testing of water wall has been settled by appropriate improvements, and the unit safety is then secured after initiation of the RB function.
  • Study on Operation Characteristics of an MPS225-HP-II Type Pulverizer in Grinding Low Quality Coal
    Yun Panfeng, Shi Yongqiang
    2017, 31(6): 448-452.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Experimental tests were conducted on operation characteristics of an MPS225-HP-Ⅱ medium speed pulverizer in grinding both normal and low quality coal, so as to obtain the operation characteristics, regulation methods and optimal operation mode of the pulverizer in grinding low quality coal, thus guiding actual operation of similar pulverizers.
  • Optimization and Application of Direct Air Cooling Systems in Coal-fired Power Plants
    Wang Dong
    2017, 31(6): 453-455.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on actual operation condition of a direct air cooling system in a coal-fired power plant in northwest China, an analysis was conducted on different combinations of the back pressure, fan velocity and fan quantity. Taking minimum total annual cost of the direct air cooling system as a target, an optimized calculation was performed, and subsequently an optimal scheme was obtained through comparative analysis on different schemes of the total annual cost, which can satisfy operation requirements of the coal-fired power unit.
  • Analysis on Operation Stability of PA, FD and ID Fan during Peak-shaving Ultra-low Load Operation of a 600 MW Unit
    Chen Xiaowen, Zhao Xingchun, Huang Cheng, Zheng Guanjie, Liu Lichen, Wang Feng
    2017, 31(6): 456-460.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To satisfy the new requirement of ultra-low load operation during peak-shaving period of a 600 MW unit, an analysis was conducted on the operation stability of its PA, FD and ID fan respectively at 15% THA and 20% THA load. Results show that both the FD and ID fan run in the stable range under different conditions. The PA fan runs stably when two coal mills are put into operation. However, the PA fan works near the stall point when only a single mill is operated, indicating that there exists potential risk of unstable operation of the PA fan.