共查询到18条相似文献,搜索用时 843 毫秒
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1000MW超超临界锅炉水冷壁壁温计算 总被引:1,自引:0,他引:1
采用分区计算简化大容量高参数超超临界锅炉炉内辐射、对流传热模型,研究炉膛水冷壁热负荷及壁温的空间分布情况,并与试验数据进行了对比,计算结果与试验值之间的偏差较小,最大为5.72%.该模型与算法可给出不同锅炉负荷条件下,水冷壁壁面热负荷与壁温沿炉膛宽度方向的分布规律.结果表明,水冷壁热负荷与壁温均呈现出中间高两端低的弧形分布.四角切圆燃烧锅炉火焰位置对炉内传热有很大影响.模拟计算可为超超临界锅炉的运行提供参考,预测了在材料允许温度范围内,火焰中心偏斜最大不超过2 m. 相似文献
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分析了造成锅炉运行中热偏差(温度偏差)的4个方面,指出运行中控制热偏差对超临界和超超临界锅炉安全运行的重要性。实现电厂高科技管理"状态检修"和"寿命监测"应该采用具有高性能的在线监测技术。介绍了电厂所采用的在线监测系统(PSSS)的主要功能。同时指出,在线监测的关键在于炉内壁温计算方法的准确性。 相似文献
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根据带节流孔圈垂直管屏超超临界直流锅炉的特点,结合景德镇发电厂实际运行状况,全面分析了锅炉水冷壁、过再热器管壁壁温偏差产生的原因。重点分析了磨组运行方式、配风方式等因素对受热面壁温的影响,通过烟气侧温度场调整,降低炉内及炉膛出口烟温偏差,达到各受热面吸热均匀,有效降低了受热面壁温偏差,为机组长期稳定运行创造了有利条件。 相似文献
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超临界和超超临界锅炉水冷壁的优化设计 总被引:6,自引:2,他引:6
阐述了超临界和超超临界锅炉水冷壁的优化设计,主要包括:下辐射区水冷壁采用内螺纹管,降低质量流速,准确掌握超临界流体热物性,减小工质焓增,减小热偏差和壁温偏差,降低局部热负荷,提高安全裕度等综合性措施。最低直流负荷优化选择综合考虑启动系统成本和变负荷运行范围以及对负荷快速变化的跟踪性能,以适应机组调峰。对1000MW超超临界锅炉垂直管屏水冷壁的流动特性进行了理论分析,强调应高度重视运行煤质变化的影响并严格监控水质。图5表1参7 相似文献
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在超临界"W"火焰锅炉水冷壁上设计安装了监测管内外壁温及管内工质温度的测量装置,得到了优化内螺纹垂直水冷壁管壁温、管内工质温度及典型负荷下炉膛截面热负荷分布等实炉运行数据。试验及研究结果表明:在机组由亚临界到超临界的转换过程中,管水冷壁管内外壁温与管内工质温度呈现剧烈变化状态,在超临界负荷下,内壁与工质的换热明显减弱,水冷壁的安全性受到威胁;管内外壁温差及内壁与工质温差沿炉膛宽度和深度方向均呈现中间高两侧低的分布,水冷壁向火侧管外壁温度大大低于设计值,水冷壁有较大的安全裕量,实际炉膛截面热负荷分布介于两种设计热负荷值之间。 相似文献
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根据实际运行数据研究了超超临界锅炉的汽温偏差变化规律和影响汽温偏差的特殊因素。指出特殊因素为:在湿态向干态转变和跨越临界点时工质热物理特性变化大;过热器系统的蒸汽流程延长、汽温偏差的累积效应增大;水煤比变化等;必须注意单侧减温水量过大,将加剧流量偏差,甚至引发临界流,进而扩大汽温偏差。实例反映的汽温偏差变化趋势为:超临界锅炉在低负荷运行阶段汽温偏差最大;在临界压力附近,汽温偏差被放大;在90%负荷以上过热器出口汽温偏差可以控制在低于5℃的设计值。对于制造、安装和焊接等工艺质量引起的超温爆管或流量偏差更要高度重视。 相似文献
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由于炉膛燃烧不理想导致水冷壁出口管的热偏差,使进入顶棚进口集箱的引入管的工质产生了较大的温差。这种热偏差在顶棚入口集箱形成了轴向壁温差,使顶棚入口集箱引出管座承受了附加的超过其工作温度下许用应力的热膨胀载荷,从而使刚度较大的集箱上层接管产生了较大的附加弯曲应力,最终导致了上层接管根部的永久性变形和角焊缝裂纹。分析这种应力产生的原因,在实际中对顶棚进口集箱引出管上层接管结构进行了改进,在运行中收到了很好的效果。 相似文献
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Jiancong Dong Tuo Zhou Xiaojiang Wu Jian Zhang Haojie Fan Zhongxiao Zhang 《热科学学报(英文版)》2018,27(6):592-601
This paper presented a coupled heat transfer model combining the combustion in the furnace and the ultra-supercritical(USC) heat transfer in the water wall tubes. The thermal analysis of the spiral water wall in a 1000 MW double reheat USC boiler was conducted by the coupled heat transfer simulations. The simulation results show that there are two peak heat flux regions on each wall of spiral water wall, where the primary combustion zone and burnt-out zone locate respectively. In the full load condition, the maximal heat flux of the primary combustion zone is close to 500 kW/m~2, which is higher than that in the conventional single reheat USC boilers. The heat flux along the furnace width presents a parabolic shape that the values in the furnace center are much higher than that in the corner regions. The distribution of water wall temperature has a perfect accordance with the heat flux distribution of the parabolic shape curves, which can illustrate the distribution of water wall temperature is mainly determined by heat flux on the water wall. The maximal water wall temperature occurs at the middle width of furnace wall and approaches 530°C, which can be allowed by the metal material of water wall tube 12Cr1MoVG. In the primary combustion zone, the wall temperatures in half load are almost close to the values in 75% load condition, caused by the heat transfer deterioration of the subcritical pressure fluid under the high heat flux condition. The simulation results in this study are beneficial to the better design and operational optimization for the double reheat USC boilers. 相似文献
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The thermal efficiency of a reheating furnace was predicted by considering radiative heat transfer to the slabs and the furnace wall. The entire furnace was divided into fourteen sub-zones, and each sub-zone was assumed to be homogeneous in temperature distribution with one medium temperature and wall temperature, which were computed on the basis of the overall heat balance for all of the sub-zones. The thermal energy inflow, thermal energy outflow, heat generation by fuel combustion, heat loss by the skid system, and heat loss by radiation through the boundary of each sub-zone were considered to give the two temperatures of each sub-zone. The radiative heat transfer was solved by the FVM radiation method, and a blocked-off procedure was applied to the treatment of the slabs. The temperature field of a slab was calculated by solving the transient heat conduction equation with the boundary condition of impinging radiation heat flux from the hot combustion gas and furnace wall. Additionally, the slab heating characteristics and thermal behavior of the furnace were analyzed for various fuel feed conditions. 相似文献
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为了研究700℃锅炉的烟气热偏差特性,采用计算流体力学的方法对1台700℃等级四角切圆П型锅炉展开数值模拟研究。基于商用的CFD软件,分析了700℃锅炉的烟气热偏差特性和形成机理,研究了燃尽风的反切和燃尽风的速度偏置对炉内速度场、温度场的影响,重点针对炉膛出口附近的速度分布和温度分布,进行烟气热偏差优化控制。结果表明:当分离燃尽风(SOFA)反切25°时,炉膛出口烟温偏差为63.23 K;相对于反切0°,烟温偏差的降幅达到51.43 K;当右侧SOFA风的速度与左侧SOFA风的速度比值为1.3∶1时,炉膛出口烟温偏差为39.31 K,相对于SOFA风没有偏置时,烟温偏差降低了23.92 K。 相似文献
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目前,燃煤锅炉三维CFD数值模拟中对炉膛水冷壁传热分布的预测大都基于给定的壁面温度边界条件。然而,此方法无法体现锅炉运行状态对壁面传热与壁温分布的影响。提出了一种基于锅炉烟气侧放热与汽水侧吸热间热平衡关系的壁面传热计算方法,并重点讨论了壁面传热系数的物理意义及取值方法。研究发现,壁面传热系数基本由壁面结渣状态决定,因此可根据壁面渣层的传热系数确定。本文方法将影响壁面传热的关键因素合理地体现在计算过程中,同时在模型复杂性与工程适用性之间保持了合理的平衡。采用此方法对一台320 MW锅炉的燃烧与传热分布进行了数值模拟,水冷壁吸热量的预测结果与锅炉运行数据吻合良好。 相似文献
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The deposition of scale on the inner surfaces of the water-wall tubes in the high heat flux regions in a steam boiler furnace can cause serious operation problems. In this paper, a numerical technique for determining the heat flux absorbed by the water-wall tubes, water-steam temperature, and thermal resistance on the inner tube surface from a temperature measured at several interior locations of the tube wall is developed. The scale deposition tube is capable of monitoring changes in the flow of heat transfer caused by scale depositions and changes due to varying furnace conditions. It can work for a long time in the destructive high-temperature atmosphere of a coal-fired boiler. The scale deposition monitor is an online plant monitoring system designed to improve the operation of steam boilers and enhance tube life. 相似文献