饱和蒸汽减温在燃机余热锅炉的应用

介绍了燃气－蒸汽联合循环电站余热锅炉过热蒸汽调温的一种方法－自身饱和蒸汽减温。对余热锅炉自身饱和蒸汽减温系统的设计进行了分析,指出了实际应用中应该注意的问题。     

Heat transfer in a large-scale circulating fluidized bed boiler

Heat transfer of a furnace in a large-scale circulating fluidized bed (CFB) boiler was studied based on the analysis of available heat transfer coefficient data from typical industrial CFB boilers and measured data from a 12 MW_e, a 50 MW_e and a 135 MW_e CFB boiler. The heat transfer of heat exchanger surfaces in a furnace, in a steam/water cooled cyclone, in an external heat exchanger and in the backpass was also reviewed. Empirical correlation of heat transfer coefficient was suggested after calculating the two key parameters, solids suspension density and furnace temperature. The correlation approach agrees well with the data from the large-scale CFB boilers. __________ Translated from Journal of Power Engineering, 2006, 26(3): 305–310 (in Chinese) [译自: 动力工程]     

链条锅炉的动态建模与仿真

针对10t／h及以下容量链条锅炉负荷的频繁波动,采用模块化的建模方式建立了一台10t/h链条锅炉的汽水系统和燃烧系统的动态数学模型,并进行了仿真试验,得到炉排速度和空气量发生变化时锅炉燃烧率、蒸汽流量、过热汽温和汽包水位的实时变化量和趋势。仿真试验结果表明,链条锅炉更好地实现负荷调整应采取同时改变炉排速度和空气量的方式,为实现锅炉的稳定性和经济性运行提供理论指导。     

Heat flux distribution on circulating fluidized bed boiler water wall

The future of circulating fluidized bed (CFB) combustion technology is in raising the steam parameters to supercritical levels. Understanding the heat flux distribution on the water wall is one of the most important issues in the design and operation of supercritical pressure CFB boilers. In the present paper, the finite element analysis (FEA) method is adopted to predict the heat transfer coefficient as well as the heat flux of the membrane wall and the results are validated by direct measurement of the temperature around the tube. Studies on the horizontal heat flux distribution were conducted in three CFB boilers with different furnace size, tube dimension and water temperature. The results are useful in supercritical pressure CFB boiler design. __________ Translated from Journal of Power Engineering, 2007, 27(3): 336–340 [译自: 动力工程]     

600 MW超临界循环流化床锅炉

超临界循环流化床(CFB)燃烧技术作为新一代CFB技术,综合了超临界蒸汽循环高效率和循环流化床低成本实现低污染排放两方面的优势,具有广阔的发展前景.介绍了国内外超临界CFB锅炉研究工作的最新进展和自行设计的600 MW超临界CFB锅炉设计.     

Heat flux distribution on circulating fluidized bed boiler water wall

The future of circulating fluidized bed (CFB) combustion technology is in raising the steam parameters to supercritical levels. Understanding the heat flux distribution on the water wall is one of the most important issues in the design and operation of supercritical pressure CFB boilers. In the present paper, the finite element analysis (FEA) method is adopted to predict the heat transfer coefficient as well as the heat flux of the membrane wall and the results are validated by direct measurement of the temperature around the tube. Studies on the horizontal heat flux distribution were conducted in three CFB boilers with different furnace size, tube dimension and water temperature. The results are useful in supercritical pressure CFB boiler design.     

Energy consumption of 270 schools in Tianjin,China

With the rapid development of education cause, the increasing energy consumption of school buildings is gradually causing widespread concern in recent years in China. This paper presented an analysis of energy consumption of 270 schools located in the city of Tianjin, China. The analysis focused specifically on calculating the space heating energy consumption indexes and non-heating energy consumption indexes of different types of schools, aiming at providing reliable and precise data for the government to elaborate policies and measures. The space heating energy consumption of schools adopting district heating and gas boiler were 92.04 kWh/(m²·a) and 64.25 kWh/(m²·a), respectively. Comparing to the schools without a canteen, the non-heating energy consumption index of schools with a canteen can increase by 8%–37%. Furthermore, clustering of different energy sources, the total primary energy consumption indexes were also presented. Space heating energy consumption accounted for approximately 64%–79% of the total primary energy consumption. When using time-sharing control and self-contained gas boiler instead of district heating, an amount of almost 27.8 kWh/(m²·a) and 77.5 kWh/(m²·a) can be saved respectively. Through extensive statistical analysis of the data collected, this paper demonstrated that gross floor area, heating energy source and canteen had a close relationship with the total primary energy consumption regarding complete schools. Eventually, a linear regression equation was established to make a simple prediction about the total energy consumption of existing complete schools and to estimate the energy consumption of complete schools to be built.     

Design and simulation of a solar-powered/fuel-assisted rankine engine for power generation

A solar-powered/fuel-assisted steam Rankine engine (SPFASRE) that generates a 36 kW steady electrical power is designed. Steam is generated at 230°C using an unfired boiler. The boiler is connected to oil loops that utilize 400 m² of single axis tracking concentrating parabolic-trough collectors and an auxiliary gas-fired heater. The steam leaving the boiler is superheated to 400°C in an LPG-fired superheater. The Rankine engine features a two-stage turbine. The calculated steam Rankine cycle's efficiency at design condition is 23·2%.

A computer program was developed to simulate the system's performance under design and off-design conditions. The results of the simulation indicate that the size of the solar collector chosen provides from 80% to 85% of the total energy required for the Rankine cycle during the summer, fall and spring seasons. In the winter season, however, about 70% of the total energy is supplied by solar energy.

This paper describes the design of SPFASRE and its seasonally projected performance for Jeddah's climate in Saudi Arabia.     

Industrial use of geothermal energy at the Tasman pulp & paper co. ltd's mill, Kawerau, New Zealand

Tasman Pulp & Paper Co. Ltd's mill at Kawerau has an annual production capacity of 380,000 tonnes of Newsprint and 200,000 tonnes of Kraft pulp. The mill electrical requirement amounts to 128MW. Geothermal steam has a significant impact on the mill energy balance and contributes around 35% of the mills steam requirements. There are five geothermal to clean steam heat exchangers with a total capacity of 140t/hr of 345kPa saturated process steam and two boiler feedwater heaters which supply two chemical recovery boilers and three power boilers. Additional geothermal steam is used to heat combustion air and operate shatter sprays at the recovery boilers. A 10MVA geothermal turbo-alternator exhausts steam to a black liquor pre-evaporator and a heat exchanger to heat clean process water. All the available geothermal condensate is collected and treated in a condensate recovery plant to meet quality specifications for boiler feedwater. This meets all of the feedwater requirements of the geothermal heat exchangers plus the make up for the recovery and power boilers. Geothermal water separated in the borefield is used by Bay of Plenty Electricity in two Ormat binary cycle turbines which generate 2.0MW nett. The discharge from the binary cycle plant is also processed in an experimental pilot scale Precipitated Silica plant to recover silca which is used as a newsprint additive. The remainder is discharged through a serpentine canal to the Tarawera river.     

350 MW余热锅炉变工况运行特性分析

  目的  整体煤气化联合循环（IGCC）发电技术是高效、低碳的发电技术,余热锅炉是IGCC的组件之一。文章旨在研究余热锅炉变工况运行特性以提高整体煤气化联合循环发电技术的效率。  方法  通过分析余热锅炉的工作原理及传热传质原理,使用MATLAB软件展开编程计算,探究给水温度、给水压力、液相换热系数以及气相换热系数与余热锅炉内吸热量的关系。  结果  结果发现,当液相换热系数在200～1 000 W/(m2·K)和气相换热系数在20～100 W/(m2·K)范围内时,如果给水温度从30 ℃增加到100 ℃或给水压力增加,余热锅炉的吸热量将不断减少。反之,假设给水温度在30～100 ℃范围内,当液相换热系数从200 W/(m2·K)增加到1 000 W/(m2·K)或气相换热系数从20 W/(m2·K)增加到100 W/(m2·K)时,余热锅炉的吸热量不断增加。  结论  在液相换热系数与气相换热系数不变的情况下,给水温度或给水压力增加,余热锅炉的吸热量会减少;在给水温度与给水压力不变时,液相换热系数或气相换热系数增加,余热锅炉的吸热量会增加。     

引进300 MW循环流化床锅炉的技术特点分析

为有效利用我国高硫低质煤资源,加快大型循环流化床(CFB)锅炉在我国的发展,国内采用引进技术制造、投运了多台 300 MW CFB锅炉.在介绍引进的 300 MW CFB锅炉结构及布置特点的基础上,重点分析了引进300 MW CFB锅炉与国内现有的100～ 150 MW级CFB锅炉所采用更新技术:裤衩腿炉膛、高的运行床压和控制系统、长入口中心筒偏置的分离器、管束管径不同的外置式换热器、将多维膨胀简化为一维膨胀的膨胀节、四分仓回转式空气预热器、汽水调节技术、互为备用的给煤线路以及溢流式风水联合冷渣器.     

300MW循环流化床锅炉热力特性的研究

为准确把握300 Mw循环流化床(CFB)锅炉的热力特性,针对目前国内3种典型300Mw CFB锅炉炉型,从炉膛、外置床的传热机理和传热计算角度出发,对不同炉型的热力特性进行了分析比较.结果表明:3种炉型CFB锅炉的热力特性均可满足蒸汽参数的要求,且热负荷分配合理.     

基于TRNSYS的太阳能谷电蓄能供热采暖系统性能研究

为了研究太阳能谷电蓄能供热采暖系统运行特性,采用TRNSYS软件建立系统各部件模型,分析了太阳能辐照强度、集热面积和空气流量对系统太阳能保证率的影响,对系统进行优化研究。结果表明：太阳能辐射强度对系统太阳能保证率的影响较大,拉萨全年太阳能保证率波动比上海和北京小;太阳能保证率与集热面积呈正相关;空气流量对太阳能保证率影响较小,当空气流量为40 m³/(h∙m²) 时太阳能保证率最大,相比36 m³/(h∙m²)工况提高了0.26%;选择集热面积为650 m²、最佳空气流量为40 m³/(h∙m²) 的优化系统,相比集热面积为716 m²、空气流量为36 m³/(h∙m²) 工况下的年均太阳能保证率降低了1.22%。本研究可为太阳能谷电蓄能系统的后续研究提供参考。     

Heat transfer with water flowing upward in a tube for pressures up to supercritical region

A heat transfer experiment was conducted in a tube of 6.07mm in diameter with water flowing upward, covering the ranges of pressure of 10―23MPa, mass flux of 288―1298kg/(m²·s), local water temperature of 78°C―270°C, heat flux of 0.23―1.18MW/m² and Reynolds number of 5.5×10³―3.9×10⁴. The experimental results were compared with the predictions of the Dittus-Boelter correlation, Jackson correlation, Bishop correlation, Swenson correlation and Yamagata correlation. Significant deterioration in heat transfer was observed in both subcritical and supercritical region due to the effect of buoyancy force, but it was not predicted reasonably by the existing correlations.     

430t/h燃印尼煤循环流化床锅炉设计与运行

出口印度尼西亚的430 t/h循环流化床(CFB)锅炉成功投运,锅炉燃烧印度尼西亚低灰分煤,能够保持正常的循环燃烧,无需添加床料,但其运行参数与国内CFB锅炉有较大不同。分析总结了出口印度尼西亚的430 t/h CFB锅炉的运行特点,结果对于其它出口印度尼西亚或者完全燃用印度尼西亚煤的CFB锅炉的设计具有较好参考意义。     

310t/h循环流化床锅炉混烧煤和石油焦热工性能试验分析

在2台310 t/h循环流化床锅炉上进行热工性能试验,分析比较了烟气温度、汽水流量、灰渣含碳量及尾部烟气污染物等参数。2台循环流化床锅炉均燃用煤和石油焦混合物,炉内添加石灰石脱硫。1#和2#锅炉额定运行负荷热效率分别为89.22%,90.70%,日常运行负荷热效率分别为88.10%,89.88%。2台锅炉炉内密相区温度分布均匀;床温、分离器入口温度、回料腿温度和排烟温度稳定;主蒸汽流量、给水流量、减温水流量波动较小;烟气污染物均可达到设计要求。试验结果可对混烧煤和石油焦循环流化床锅炉的设计和运行提供参考。     

烧失量法测量循环流化床锅炉飞灰碳的系统误差

1前言飞灰的可燃碳含量决定了其在建材方面的应用范围。通常用烧失量(LOI:Loss-On-Ignition)来表征粉煤灰可燃碳含量的大小。例如我国在GBJI46-90,GBI596-91和FGJ28-86等标准中规定,用烧失量表征的可燃碳含量小于飞灰总质量5%的飞灰为I级灰,在5%~8%之间的为II级灰,在8%~15%之间     

100 MW级蒸汽轮机系统稳态变工况运行特性

  目的  为有效提高循环效率,整体煤气化联合循环（Integrated Gasification Combined Cycle, IGCC）发电系统因其自身所具备的热效率高、污染小、运行灵活等优势得到广泛关注。余热锅炉与蒸汽轮机共同构成了联合循环系统的底循环。  方法  文章主要采用能量平衡和热力学计算公式,运用MATLAB进行建模运算,研究了蒸汽流量、给水温度、过热蒸汽温度和再热蒸汽温度的变化对蒸汽轮机的输出功率、热效率和蒸汽总吸热负荷的影响,同时在稳态运行的条件下,对底循环的工作原理和传质传热流程进行分析。  结果  结果表明:增加高压蒸汽流量,减小低压蒸汽流量,可以在具有较高热效率前提下,使蒸汽轮机输出更高的功率。在优化运行参数下,吸热负荷比参考工况减小了45.7 kW,热效率由23.82%增至26.92%。  结论  高压过热蒸汽和再热蒸汽的温度升高,蒸汽轮机系统热效率越高,但吸热负荷和输出功率变化幅度很小,可适当提高高压过热蒸汽和再热蒸汽的温度,有利于提高蒸汽轮机的热效率。而给水温度升高时,输出功率不随给水温度发生变化,而蒸汽吸热负荷会随着给水温度的升高而降低。给水温度越高,蒸汽所需热负荷就越小,有利于减少热能的输入而提高蒸汽轮机的热效率。     

Improving Steam Boiler Operation by On-Line Monitoring of the Strength and Thermal Performance

The operation of steam boilers with high efficiency requires control of thermo-hydraulic and strength parameters in the on-line mode. During operation under transient conditions, there are significant temperature differences over the circumference of the horizontal pressure vessels. This occurrence is caused by the different values of heat transfer coefficients on the inner surface of the boiler drum in the water and steam region. Large thermal stresses can occur in partially filled horizontal vessels. This takes place in large steam generator drums, superheater headers, and steam pipelines. The paper presents a method for determination of thermo-flow parameters for steam boilers. This method allows performing the calculations of the boiler furnace chamber and heating flow rates absorbed by superheater stages. These parameters are important for monitoring the performance of the power unit and determining the degree of the furnace chamber slagging. Knowledge of these parameters allows determining the degree of the furnace chamber slagging. The calculation can be performed in online mode and use to monitoring of steam boiler. The presented method allows to the operation of steam boiler with high efficiency.     

Effect of heat transfer coefficient of steam turbine rotor on thermal stress field under off-design condition

The precise calculation of temperature and thermal stress field of steam turbine rotor under off-design conditions is of paramount significance for safe and economic operation, in which an accurate calculation of heat transfer (HT) coefficient plays a decisive role. HT coefficient changes dramatically along with working conditions. First, a finite element analysis of rotor model, applied with ordinary rotor materials, has been conducted to investigate the temperature and thermal stress difference along with the change of HT coefficient from 20 W/(m²·°C) to 20000 W/(m²·°C). Next, the differentiation between existing empirical formulas has been analyzed from the aspect of physical significance of non-dimension parameters. Finally, a verifying case of the cold startup of a 1000MW unit has been proceeded. The result shows that the accuracy of coefficient calculation when steam parameters are low has a greater influence on that of rotor temperature and thermal stress, which means a precise empirical HT coefficient formula, like the Sarkar formula is strongly recommended. When steam parameters are high and HT coefficient is larger than 10⁴ W/(m²·°C), there will be barely any influence on the calculation of thermal stress. This research plays a constructive role in the calculation and analysis of thermal stress.