Table of Content

25 September 2019, Volume 41 Issue 9

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Research on gas turbine combustion pressure fluctuation and the key technologies for its measurement

LIU Zhimin1,2, DING Yang1, XU Tingting1,BAI Yunshan1

2019, 41(9):  1-5. 

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Gas turbine combustion oscillation is a key and unavoidable problem in premixed combustion technology. The mechanism of combustion pressure fluctuation is the basis for solving this problem. Analysis and measurement on combustion pressure fluctuation is an effective supplement for the basic experiment. The mechanism of gas turbine combustion pressure fluctuation is analyzed with combustion mechanism, simple feedback model, openloop gain and Bode plot. Considering the location of pressure transducers and the type of transducers, the key technologies for combustion pressure fluctuation measurement and  typical measurement procedures are introduced.

Effect of smoke box structure at ESP inlet on gas flow distribution and optimization based on numerical simulation

XIONG Yuannan1，WANG Yongwei1，CHEN Yingwu2

2019, 41(9):  6-11. 

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Asymmetric structure of original inlet smoke boxes and irrational arrangement of  deflectors and orifice plates of an electrostatic precipitator (ESP) for 2×300MW units in a power plant were conducive to the flow field nonuniformity.Numerical simulation was made on inlet smoke box, which focused on the influence of its structure on airflow distribution. It is found that deflectors play a major role in balancing gas distribution between two smoker boxes and adjusting smoke flow direction, however, they have limited  improvement on airflow distribution uniformity.The orifice plates can effectively improve the uniformity of gas velocity distribution.There is regularity in the optimized layout of orifice plates which is the uniformity of airflow distribution can be improved with the decrease of orifice plate installation spaces and the increase of the percentage of open areas.With a better airflow distribution uniformity, the dustremoval efficiency can be raised. By analyzing field test results and the numerical simulation results, the accuracy and reliability of numerical simulation were confirmed.

Analysis of temperature field and thermal stress of hightemperature steam pipe elbow in startup stage

LIU Ming1，ZHU Weixiong2，DING Yongneng2，BAI Jia1

2019, 41(9):  18-21. 

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To analyze the thermal stress of highpressure main steam pipe precisely,the elbow of highpressure main steam pipe in a gas turbine power plant was taken as the research object.According to the actual startup and shutdown curves of the turbine, the temperature field and thermal stress field of the elbow during cold startup were analyzed by limited element method.The results showed that the thermal stress of the elbow increased rapidly in the first 10 min of the startup stage, then increased steadily. The maximum stress lied on the neutral surface of the elbow, and the peak stress occurred at the last moment of steam temperature rise.With the stability of steam temperature, the thermal stress decreased rapidly.The results can provide reference for structural fatigue damage analysis.

Study on the structure design of quadrangle towerframe steel chimney

XIA Huaipeng，WANG Zhengrong，WANG Yang，HU Xiaofu，WU Chong

2019, 41(9):  22-24. 

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To understand the deformation of quadrangle framed steel chimney under different loads,a modal analysis was carried out using the finite element program MIDAS. The stress of  the frame and chimney should be taken into account at the same time. The mode of the towerframe steel chimney was affected by the opening at bottom, and the stress in the diagonal direction is most unfavorable to the structure. The temperature load has a great influence on the column feet of a hightemperature chimney, and reasonable structural measures must be taken to release the temperature stress. The steel frame should be slidably connected to the cylinder of the chimney on Y direction, releasing the freedom degree and reducing the thermal deformation.

Research on online performance test of gassteam combined cycle units

GONG Wenming1，LI Wei2，LI Ming2

2019, 41(9):  25-28. 

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机组性能试验是掌握火力发电机组、系统和热力设备等运行经济性的重要技术手段。为全面实时地对燃气-蒸汽联合循环机组进行性能监测，采用maxDNA组态语言与C语言联合编程，开发了一套在线性能试验系统，在系统中植入联合循环机组相关计算公式，通过计算模块对机组进行在线性能试验，实时监测机组的状态，为电厂节能监督工作提供技术支持，提高燃气发电机组的运行水平。

Influence of 600MW supercritical unit steam distribution characteristics on shaft vibration

CHEN Hao，XU Junfeng

2019, 41(9):  29-32. 

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Highparameter steam turbines’steam distribution characteristics affect their operating economy and shaft stability under partial loads. Analyzing the steam distribution adjustment test of a 600MW supercritical unit, its steam distribution characteristics are studied. An optimal valve sequence, and the relationship between the load with optimal steam distribution mode and the opening degree of the main steam regulating valve are obtained. The results show that adjusting the steam distribution mode can effectively eliminate the selfexcited vibration  and improve the shafting stability without shutdown the machine. The research results can provide guidance for fault handling and optimized operation.

Stress test and analysis of submerged radial gate structure of hydropower station

ZHU Chen，XU Yaowei，YU Shumin

2019, 41(9):  33-35. 

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In order to measure the structural strength of the submerged radial gate of hydropower station,strain electrical measurement method is used to test the structural stress of a submerged radial gate under three working conditions when hydropower station adjusts its water level.Considering the special working condition of submerged radial gate,effectively protection is made on resistance strain gauge to ensure the stability of the test.The test results show that the test is stable and the data of each test point is normal.The test data is analyzed in combination with the running state of the radial gate,the stress distribution is obtained.And the safty of structural strength of the radial gate is evaluated.

Design and application of cablestayed device for trapping and raising floating trash

YANG Xiaodong1，SHANG Liyang1，FAN Suxiang2，YU Penghui1

2019, 41(9):  36-38. 

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To protect the water along the main canal of the middle rout project in SouthtoNorth Water Diversion from being affected by floating trash at intakes, a cablestayed  device for trapping and raising floating trash was designed.Without damaging the original structure of the hydraulic structure, a trapezoidal trapping frame covered with filter was articulated in the front of diversion gate, and it was adjusted by winch hoist. The device effectively avoided various floating debris in main canal flowing from water diversion to intakes,which fundamentally solved the problem blockage of valves and equipment in water plants, and improved their production efficiency.

Design of test platform for power distribution master station combining virtuality and reality

ZHAO Zhonghua，AI Shaowei，FENG Hao，HE Gang，ZHU Junhong

2019, 41(9):  39-41. 

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Power distribution master stations have many access nodes, large data volume, and complex topological structure. It is impossible to test the mater station system on a real power distribution network. Therefore, it is necessary to set up a test platform to verify the function, performance, pressure, etc. of the power distribution master station. After analyzing the test requirements and onsite operation requirements, a test platform combining virtual and real is designed. The platform operates tests using real terminals, virtual terminals, real time digital simulator(RTDS), cloud platform and NTM mass storage device.The test platform is simple to operate, has a wide test coverage, and is of extensibility and effectiveness.

Selection and analysis for  filtering media of ultraclean electrostatic fabric  precipitators

PENG Geliang，WANG Junwei，TAN Zhilin，LI Lianjun

2019, 41(9):  42-44. 

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To study the operation of ultraclean electrostatic fabric precipitators,the filter media composition,filtration wind speed,dust concentration discharged at outlet and the equipment resistance are analyzed based on 10 coalfired units in operation.The results show that the dust removal efficiencies of ultraclean  electrostatic fabric precipitators reduce with the increase of  filtration wind speed,and the dust concentrations discharged at outlets decrease with the drop of the filtration wind speed.Controlling the filtration wind speed can also effectively control the resistance of precipitator.Therefore,ultraclean electrostatic fabric precipitator can achieve dust ultralow emission by selecting appropriate filtering media and controlling the filteration wind speed.

Experiment on energy saving optimization test of desulfurization and oxidation fans for 350MW units

ZHAO Linlin

2019, 41(9):  45-48. 

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Taking the operation mode of a desulfurization and oxidation fans for a 350MW unit as research object, by monitoring the operation mode within 2 oxidizing fans and 1 oxidizing fan，the relationships between the dissolved oxygen concentrationin of desulfurizing absorber slurry and the unit load, the SO2 concentration at FGD inlet and the pH of the slurry are obtained. At the same time,1.5mg/L dissolved oxygen is selected as the standard line of full oxidation of slurry，which determines the optimum operation mode of the oxidizing fan at different loads and SO2 concentrations at the inlet of FGD.The results show that by optimizing the operation of the oxidizing fan, the power consumption for the plant can be saved by 1.1×106kW·h every year. It is of great significance to the energy saving and environmental control of the desulfurization system in the power plant.

Discussion on energysaving scheme for cooperative desulfurization with liquid column injection and atomization spray

YANG He，LIU Fangfang，XI Lin

2019, 41(9):  49-52. 

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To realize the energysaving operation of desulfurization system, a new scheme for cooperative desulfurization with liquid column injection and atomization spray  was proposed.After removing 2 spray layers at bottom and adding 2 liquid column injection layers over the rotating coupling layer, slurry injection flow could be controlled by variablefrequency circulation pump.The scheme reduced the resistance of flue gas , and realized the linear adjustment and automatic control on the slurry circulation flow, which is of great energysaving effect.

 

Fault analysis on desulfurization DCS signal interference in a thermal power plant

MA Liang，FU Ran

2019, 41(9):  53-55. 

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The desulfurization DCS of a thermal power plant suffers from multiple signal interference,which seriously affects the stable operation of the unit.Six signal fluctuation situations are introduced and troubleshooting is made from interference sources,propagation paths and sensitive bodies.Rectification measures such as renovating the road light power supply circuit, standardizing the DCS grounding,cleaning the cable trench are proposed.After the rectification,the system is more stable and there is no signal interference in it.

Retrofit of lownitrogen burner in lean coal boiler with storagetype hot air pulverized coal feeding system

YANG Haiyong1，XIONG Xianwei2，RAN Guilin1

2019, 41(9):  56-58. 

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Unburned combustible in fly ash and hightemperature exhausted gas is prevail in storagetype hot wind pulverized coal feeding system of lean coal boilers taking staged combustion.Tertiary air richlean separation and rearranging the tertiary air nozzles was proposed as a retrofit scheme. After retrofitting, when the content of volatile matter decreased,the mass concentration of NOx at the economizer outlet decreased from 620.75mg/m3 to 487.00mg/m3，and unburned combustible in fly ash and slag decreased as well，and so did the temperature of exhausted gas，which met the expectation of lownitrogen burner retrofit.

Analysis of FCB function in Yangmei Xishangzhuang 2×660MW thermal power units

BAI Changqing

2019, 41(9):  59-62. 

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The significance of fast cut back (FCB) function for highcapacity units in thermal power plants ,and the importance of implementing FCB for 2×660MW units in Yangmei Xishangzhuang thermal power plant is introduced. This function can realize the operation on isolated network when there is fault in power grid, realize quick restoration of power transmission at any time,and improve the survival opportunity in the case of grid collapse.It reflects the social value of the power plant.Based on the experience of  FCB function implemented in some supercritical units of 600MW or above in domestic power enterprises, analysis on application of  FCB function in Yangmei Xishangzhuang 2×660MW thermal power units is proposed according to the characteristics of  its main and auxiliary machine configuration.It provides technical exploration and support for the implementation of FCB function during the pilot phase of the project

Setting coordination of field loss protection with admittance and excitation device low excitation limit

ZHANG Bo

2019, 41(9):  63-66. 

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To prevent the generator field loss protection from being misoperated, it must coordinated with  excitation device low excitation limit.Based on the calculation formula of power, it deduced the process of transformation from P-Q plane into admittance plane, and introduced the principle of field loss protection with admittance and the principle of low excitation limit of ABB U6800 excitation device. Taking the No.3 generator of Shanghai Shenergy Lingang CCGT Power Generation Company Limited as an example, the calculation of generator field loss protection was set up. The actual capability of leading phase of the No.3 generator was tested, and the exact parameters of the low excitation limit of the excitation device were obtained. At the end, the setting coordination of generator field loss protection and excitation device low excitation limit was checked, so as to ensure low excitation limit to precede field loss protection, and prevent the field loss protection from being misoperated.

Feasibility research on redundancy removal and derating of coal handling systems in large and medium coalfired power plants

LI Jichuan

2019, 41(9):  67-69. 

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At present, the working hours of coalfired  units are declining, and there is great redundancy in the output of coal handling systems. Based on the status quo and expectation for power generation market, it analyzed the operational reliability and output of the coal handling systems and proposed feasible redundancy removal schemes.Under the premise of dualconfiguration for coal handling systems, it is feasible to cut the redundant ouput. It is recommended to reduce the output of the coal system and optimize the system configuration in new or rebuilt projects.

Heatsupply modification for  9F gassteam combined cycle units

LIU Zhongyuan

2019, 41(9):  70-71. 

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In order to further improve the energy utilization rate of the gassteam combined cycle units and meet a higher heating demand, the original heatsupply scheme for units need to be modified. Taking 9F gassteam combined cycle units in a power plant as an example, the actual operation of the unit after modification was briefly described. The advantages and disadvantages of three heating modification schemes were analyzed in detail. The parameters after modification were analyzed，and the results show that the modification has improved the performance of heat supply and ratio of heattoelectricity, and reduced gas consumption for power generation， which provides reference of the modification for units of the same type.

Quality evaluation and performance analysis of WC9 cast steel safety valve for inservice units in a thermal power plant

LI Ge，ZHU Haibao，QIAO Lijie，CHEN Zhuoting

2019, 41(9):  72-75. 

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WC9 cast steel is commonly used in components of thermal power plants. Domestic and international standards do not have relevant requirements for their hardness and metallographic structure. It is difficult to evaluate  quality of cast steel valves for inservice units only by onsite inspection. Through the specific case study, it expounded how to make quality evaluation and performance analysis for safety valves running for nearly 30,000 hours of inservice units in thermal power plants. Effective method was finally proposed and was of great significance for the safe and reliable operation of the power plant in the future. At the same time, it is also suggested that  power plants and suppliers should make  requirements on hardness and metallographic organization as a supplement to the standard through consultation, which can provide references for the later inspection during the operation.

Optimization of air preheater leakage control system in 670MW unit

SONG Baoyu，YUE Hao

2019, 41(9):  76-77. 

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There is increasing gap between the sector plate and the rotor radial seal plate of the air preheater in 670MW unit of Huadian Weifang Power Generation Company Limited.An optimization method of control system is proposed to address the air preheater leakage. Linear variable differential transformer (LVDT) is used to measure the travel distance of the lifting mechanism, which can control the travel of sector plate accurately and effectively reduce the air leakage rate of air preheater under the premise of stable operation. The economy of unit can be improved.The method can provide reference for the safe and economic operation of units of the same type.

Transformation methods for PT slowmelting judgment of UN 5000 excitation system

LIANG Guozhu

2019, 41(9):  78-80. 

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An excitation system should provide complete judgment function for PT disconnection to prevent the generator set tripping caused by excitation system overexcitation. Since the shortcomings of the original PT disconnection logic of  UN 5000 excitation system, there are hidden dangers of overexcitation in excitation system caused by PT slow melting.By attaching an external detection device for PT disconnection or setting up a PT slowmelting logic inside the software,  the hidden danger  caused by PT slow melting can be eliminated, and the reliability of generator sets can be improved.