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锅炉给水泵转子动力学参数的一、二阶摄动识别研究 总被引:2,自引:0,他引:2
锅炉给水泵的临界转速是非常重要的参数,与结构密切相关。为了准确地计算出给水泵的干临界转速(在空气中)和湿临界转速(在水中),必须知道转轴上的零部件对其弯曲刚度的加强作用。本文利用摄动传递矩阵法,结合实验室的试验数据,对某电站锅炉给水泵转子的动力学参数进行了一阶和二阶摄动识别。给出了给水泵转子上的热装叶轮、轴套对转子刚度产生加强作用的一、二阶摄动识别结果,得到了修正的给水泵转子系统动力学计算模型。由修正模型计算得到的转子系统固有频率与实测的转子系统固有频率吻合良好。指出一阶摄动识别的结果可以满足工程实际的精度要求。 相似文献
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The heat transfer process occurring in a condensing heat exchanger where noncondensible gases are dominant in volume is different from the condensation heat transfer of the water vapor containing small amount of noncondensible gases. In the process the mass transfer due to the vapor condensation contributes an important part to the total heat transfer. In this paper, the Colburn-Hougen method is introduced to analyze the heat and mass transfer process when the water vapor entrained in a gas stream condenses into water on the tube wall. The major influential factors of the convective-condensation heat transfer coefficient are found as follows: the partial pressure of the vapor p
v
, the temperature of the outer tube wall T
w
, the mixture temperature T
g
, Re and Pr. A new dimensionless number Ch, which is defined as condensation factor, has been proposed by dimensional analysis. In order to determine the relevant constants and investigate the convection-condensation heat and mass transfer characteristics of the condensing heat exchanger of a gas fired condensing boiler, a single row plain tube heat exchanger is designed, and experiments have been conducted with vapor-air mixture used to simulate flue gases. The experimental results show that the convection-condensation heat transfer coefficient is 1.52 times higher than that of the forced convection without condensation. Based on the experimental data, the normalized formula for convention-condensation heat transfer coefficient is obtained.
A
heat transfer area m2
-
Ch
condensation factor
-
c
p
specific heat at constant pressure, J/(kg·K)
-
G
mass flux Kg/(m2·s)
-
h
heat transfer coefficient W/(m2·K)
-
J
J-factor
-
Nu
Nusselt number
-
pa
pressure
- Pr
Prandtl number
-
Q
heat transfer rate
-
q
heat flux W/m2
-
r
latent heat, kJ/kg
- Re
Reynolds number
-
Sc
Schmidt number
-
T
temperature, C or K
-
heat conductivity m W/(m·K)
-
density, kg·m3
-
g
gas
-
h
moistened hot air
-
i
interface
-
v
vapor
-
w
water 相似文献
5.
Tin is a typical residual element in steel and mainly originates from Sn-containing complex iron ore and steel scrap. The segregation of Sn in steel is harmful to the performances of steel. In this paper, the micro-segregation of residual element Sn during the solidification process of boiler and pressure vessel steel by micro-segregation model was studied. The results showed that the micro-segregation degree of Sn reduces apparently with the increase of cooling rate and remarkably deteriorates during the solidification process. When the initial content of C is higher than 0.1%, it will cause the solidification transform of the solid phase converting from the ferrite phase to austenite phase and the significant increase in the micro-segregation degree of Sn. However, increasing the initial contents of Si, Mn, P and S separately has non-significant effects on the micro-segregation degree of Sn. In addition, the improvement of initial content of Sn will lead to the micro-segregation degree decrease of Sn and has an inapparent impact on zero strength temperature and zero ductility temperature of the boiler and pressure vessel steel. 相似文献
6.
Xiaofang Zhang Li Dong Juwei Zhang Yajun Tian Guangwen Xu 《Journal of Analytical and Applied Pyrolysis》2011,91(1):241-250
Simulating the conditions of pyrolytic topping in a fluidized bed reactor integrated into a CFB boiler, the study was devoted to the reaction fundamentals of coal pyrolysis in terms of the production characteristics of pyrolysis oil in fluidized bed reactors, including pyrolysis oil yield, required reaction time and the chemical species presented in the pyrolysis oil. The results demonstrated that the maximal pyrolysis oil yield occurred on conditions of 873 K, with a reaction time of 3 min and in a reaction atmosphere gas simulating the composition of pyrolysis gas. Adding H2 and CO2 into the reaction atmosphere decreased the pyrolysis oil yield, while the oil yield increased with increasing the CO and CH4 contents in the atmosphere. TG-FTIR analysis was conducted to reveal the effects of reaction atmosphere on the chemical species present in the pyrolysis oil. The results clarified that the pyrolysis oil yield reached its maximum when the simulated pyrolysis gas was the reaction atmosphere, but there were slightly fewer volatile matters in the pyrolysis oil than the oil generated in the N2 atmosphere. All of these results are expected not only to reveal the composition characteristics of the pyrolysis oil from different conditions of the coal topping process but also to optimize the pyrolysis conditions in terms of maximizing the light pyrolysis oil yield and quality. 相似文献
7.
300 MW等级燃煤机组煤粉炉与循环流化床锅炉汞排放特性比较 总被引:3,自引:0,他引:3
MW等级燃煤机组煤粉炉与循环流化床锅炉汞排放特性比较 《燃料化学学报》2017,45(8):1009-1016
选取某地330 MW煤粉炉(PC炉)和350 MW循环流化床锅炉(CFB)的燃煤电厂进行汞排放特性的研究。采用30B法和安大略法对两个燃煤电厂的除尘器入口、除尘器出口、脱硫塔出口和湿式电除尘器出口的烟气进行了取样和汞浓度分析,采集了入炉煤和副产物底渣、飞灰及脱硫石膏样品。通过样品中汞含量的分布,探讨了PC炉与CFB锅炉机组现有污染物控制设备对汞的协同脱除作用。结果表明,350 MW CFB电厂除尘器出口烟气平均汞浓度降低至0.43μg/m~3,布袋除尘器对汞的捕获效率达到98.9%,相应的燃烧副产物中飞灰是汞的主要富集对象。对于330 MW PC炉电厂,除尘器入口和除尘器出口烟气汞浓度均高于350 MW CFB电厂,烟气汞浓度从除尘器入口、除尘器出口到脱硫塔出口依次降低,在脱硫塔出口烟气汞浓度降低至0.42μg/m~3,静电除尘器和湿式脱硫塔对烟气汞的捕获效率分别为75.0%和22.4%,相应的产物中飞灰和脱硫石膏中汞都有一定程度的富集。 相似文献
8.
四角切圆炉膛三维温度分布优化控制建模研究 总被引:2,自引:0,他引:2
炉膛燃烧三维温度分布可视化技术为实现炉内燃烧三维温度分布优化控制奠定了基础。本文采用数值计算的方法建立了炉内不同高度特征截面平均温度及相应的温度中心坐标作为中间被控变量,以各层各角燃烧器燃料量及一次风、二次风量等参数为输入变量的线性模型。检验结果表明该模型能正确反映输入变量的变化对炉内温度分布的影响,为采用自适应遗传算法实施燃烧优化控制创造了条件。 相似文献
9.
660 MW超临界W火焰锅炉低负荷稳燃特性研究 总被引:1,自引:0,他引:1
“碳中和”、“碳达峰”的提出预示着未来煤电机组将在更低的负荷运行,用于燃烧无烟煤、贫煤等低挥发份煤种的W火焰锅炉低负荷运行时会出现燃烧稳定性问题。以某660 MW超临界W型火焰锅炉为对象开展了针对低负荷稳燃特性的研究,进行了100%、60%、55%、45%THA工况的试验研究与数值模拟解析,35%THA工况理论预报。结果表明由于炉膛温度降低、煤粉变细、煤粉浓度降低的综合影响,负荷对煤粉颗粒的着火距离影响不大;低负荷工况下投运两侧燃烧器、减少乏气风的射入量有利于提高燃烧稳定性;通过数值模拟可知35%THA工况无法保持炉内高温火焰稳定燃烧,模拟预报锅炉会熄火。 相似文献
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