共查询到20条相似文献,搜索用时 109 毫秒
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The assessment of the influence of fouling and slagging on the heat transfer in utility boilers has obtained significant interest both during boiler design and operation. This paper presents a strategy to investigate this influence by introducing heat resistance to represent fouling and slagging on furnace walls. The evaluation of this strategy was performed using the plant heat flux reading data together with a 3‐D computational fluid dynamics code. The model considers the influence of the operating conditions to the incident heat fluxes and these are used to assess the heat transfer resistance from the measured absorbed heat fluxes. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Mamoru Ozawa 《传热工程》2013,34(3):13-24
This article begins with a brief review of the similarity law of conventional fossil fuel-fired boilers. The concept is based on the fact that the heat release due to combustion in the furnace is restricted by the furnace volume but the heat absorption is restricted by the heat transfer surface area. This means that a small-capacity boiler has relatively high specific furnace heat release rate, about 10 MW/m 3 , and on the contrary, a large-capacity boiler has a lower value. The surface heat flux limit is dominated mainly by the critical heat flux (CHF) inside the water wall tubes of the boiler furnace. This heat flux limit is almost the same order, independent of the capacity of the boiler. For the safety of water walls, it is essential to retain a good amount of water circulation, i.e., the circulation ratio and velocity of the water must be high enough above the respective critical values. This principle is common knowledge in boiler designer, but the actual situation is not the case. Newly designed boilers often suffer from similar accidents, especially burnout due to water circulation problems. This article demonstrates recent accidents encountered in practical boilers, and raises rather classical but important problems related to two-phase flow and heat transfer. 相似文献
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《Applied Thermal Engineering》2000,20(6):545-558
The extreme steam temperature deviation experienced in the superheater and reheater of a utility boiler can seriously affect its economic and safe operation. This temperature deviation is one of the root causes of boiler tube failures (BTF), which causes about 40% of the forced power station outages. The steam temperature deviation is mainly due to the thermal load deviation in the lateral direction of the superheater and reheater. This variation is very difficult to measure in situ using direct experimental techniques. In this paper, we propose a thermal load model that is based on the power plant thermodynamic parameters, thermal deviation theory, and flow rate deviation theory. It is found that the calculated results from our model agree well with the in situ experimental results. The predicted BTF positions are the same as that in the reheater of a 300 MW utility boiler at Wujing Power Plant. The proposed model has been used to improve the design of utility boiler in Boiler Works, predict the possible BTF in the design stage, and assess the existing designs. This model can also be applied to utility boilers of different manufactures, and has been successfully applied to the BTF prediction and prevention in the Power Station. 相似文献
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针对在线监测电站锅炉对流受热面积灰的需要,建立了对流受热面的污染监测模型.以HG1021/18.2-YM9型锅炉为监测对象,开发了受热面积灰在线监测系统,成功实现了锅炉对流受热面污染的在线监测. 相似文献
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珠海发电厂燃煤锅炉印尼煤掺烧运行特性与优化 总被引:3,自引:0,他引:3
介绍了珠海发电厂700 MW机组锅炉掺烧印尼煤的试验情况.针对印尼煤高挥发分、高水分、低灰分、热值较低的特性,提出了切实可行的掺烧措施.重点分析了珠海发电厂锅炉在掺烧印尼煤时对制粉系统安全运行、锅炉结渣、主要辅机运行情况等方面的影响,提出了掺烧印尼煤应注意的问题.同时在试验和运行结果分析基础上,采用遗传算法对珠海发电厂印尼煤掺烧进行优化.通过研究为锅炉多煤种掺烧积累了经验,扩大了锅炉燃煤的适用范围. 相似文献
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为实现对燃煤锅炉无烟温测点的对流受热面积灰程度的监测,对锅炉对流受热面的传热特性及工质吸热特性进行热平衡机理分析,在热力学基础上,用相关性分析、回归分析和灰色关联分析方法对实际生产数据进行挖掘、分析,计算了对流受热面的出入口工质温差与清洁因子的灰色关联特性,建立了利用受热面进出口温差表征积灰程度的函数模型。结果表明:负荷稳定时,锅炉燃烧释放的热量也是一定的,对流受热面单位工质吸热量能反映该对流受热面的积灰程度;受热面温差与清洁因子具有极强的关联性,受热面进出口工质温差模型能很好地反映对流受热面的积灰程度。 相似文献
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针对在线监测电站锅炉对流受热面积灰的需要,建立了对流受热面的污染监测模型。以某300 MW机组的1 025 t/h锅炉为监测对象,开发了受热面积灰在线监测系统,成功实现了锅炉对流受热面污染的在线监测。 相似文献
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Co-firing trial tests of sawdust and bio-waste coming from cereal production with hard coal were carried out at Skawina Power Plant in Poland (1532 MW in fuel, currently belonging to CEZ Group). Skawina Power Plant is a tangentially-fired pulverized coal unit with nine boilers (4 boilers of 210 t/h and five boilers of 230 t/h live steam respectively) that produces 590 MW electricity and 618 MW of heat (district heating and process steam).The paper presents an analysis of energy and ecological effects of sawdust and bio-waste co-firing in the existing pulverized hard coal boiler. The mixture of coal and biomass was blended in the coal yard, and fed into the boiler through the coal mills. During the tests, combustion of mixtures composed of hard coal and sawdust (with mass share of 9.5%) and hard coal – bio-waste (6.6% mass basis) were examined. The co-firing tests were successful. Based on the analysis of the test results, the influence of biomass co-firing on specific components of energy balance (e.g. stack losses and boiler thermal efficiency) was discussed, in comparison to combustion of coal alone. The emission indices during coal combustion were calculated and compared to the emission indices for biomass co-firing. It was proved that co-firing of both biomass sorts leads to a decrease of CO and SO2 emissions. Due to the possibility of considering the part of the energy generated during biomass co-firing as renewable energy, the procedure for biomass based renewable energy share determination is presented and illustrated with an example. 相似文献
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∏形布置的水管锅炉,后部转弯烟道内的烟气偏流会带来对流受热面的传热和温度偏差。当偏差较大时,会影响锅炉的整体运行性能。以一台70 MW热水锅炉为例,为减小转弯烟道内受热面的传热和温度偏差,结合流场数值分析调整烟道形状和尺寸,以确定合理的结构改进方案。方案实施后,经运行监测,对流管束前后部的温度偏差由17℃降低到3℃,其他相关的运行参数也都接近于设计值,取得了预期效果。 相似文献
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减轻锅炉结焦的运行方案的计算与分析 总被引:1,自引:0,他引:1
沙角C电厂共有2台锅炉,均为美国ABB-CE公司的汽包锅炉,平行通风方式露天布置,连续蒸发量为2 100 t/h,不投油最低稳燃负荷为230MW,1996年6月投运以来,结焦较为严重.本文利用计算机模拟的方法对锅炉的流动、传热及其燃烧过程进行了计算机数值计算,变工况调节.以计算机数值模拟的方法分析方法找出了锅炉结焦的原... 相似文献
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根据300MW循环流化床(CFB)锅炉现场测试数据并结合以往CFB锅炉传热系数的研究成果,建立了屏式受热面烟气侧的传热模型,包括辐射传热模型和对流传热半经验公式.利用该模型对某300MWCFB锅炉在94%锅炉最大连续蒸发量(BMCR)工况下炉膛内屏式受热面的传热系数进行了计算,分析了屏式受热面管间节距、炉膛温度、工质温度、壁面黑度及烟气速度等因素对传热系数的影响.结果表明:烟气速度、炉膛温度和壁面黑度对传热系数的影响较大,所建立的传热模型能够合理地反映主要因素对CFB锅炉屏式受热面传热的影响. 相似文献