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论文题目：锅炉过热器 姓 名：******* 班 级：热动11301 学 号: 2011242401** 授课教师：于 澄 洁
一、课题名称：
中文题名：锅炉过热器 英文题名： Boiler Superheater 中文关键词：过热器 英文关键词：Superheater
二、课题概述：（约200～300字）
锅炉过热器是把饱和蒸汽加热到额定过热温度的锅炉受热面部件。回收锅炉烟气能量，使锅炉出来的蒸汽可以获得加热，变为干蒸汽，有利于提高锅炉热效率，也有利于蒸汽轮机避免水击 。过热器可根据布置位置和传热方式分为几类，
一、对流式过热器，
二、屏式过热器，
三、辐射式过热器，
四、炉顶过热器与包墙管过热器工业锅炉的过热器均为对流式过热器，现代大型电站锅炉的过热器则常由对流式，半辐射式和辐射式过热器组成。
三、《中国学术期刊全文数据库》（http://dlib.cnki.net） 列举出部分检索结果（含摘要）。
1、锅炉过热器动态特性数理分析及其状态观测器的鲁棒性 【作者中文名】 韩忠旭
【作者英文名】 HAN Zhong-xu~(1,2) (1.China Electric Power Research Institute, Beijing 1000 85, China; 2.Beijing Stage Power Zhishen Control Technology Ltd.Beijing 100085, China) 【机构】 中国电力科学研究院 北京 100085 北京国电智深控制技术有限公司； 北京 100085；
【摘要】 该文以过热器蒸汽温度受控对象为例,剖析了单相受热管焓-温通道的几种集总参数数学模型,它们共同的特性是特征方程的解均为实数根,从而具有过阻尼的性质。在此基础上,进一步揭示应用高阶等容惯性环节作为锅炉过热器蒸汽温度受控对象的状态观测器这一方法内在的数学与物理基础,进而得出在设计锅炉过热器蒸汽温度受控对象的状态观测器时,不必受对象阶数的限制,通过调整观测器的参数,同样可以很好地完成重构状态并进行极点配置,起到改善受控系统动态特性的设计效果。工程实践表明:采用高阶惯性环节作为过热器蒸汽温度的状态观测器是可行的,适用的。 更多还原
【关键词】 锅炉过热器； 动态特性； 状态观测器； 温度控制系统； 鲁棒性；
2、锅炉过热器管道热流密度的评估方法
【作者】 徐鸿； 赵志渊； 林振娴；
【Author】 XU Hong,ZHAO Zhi-yuan,LIN Zhen-xian(School of Energy,Power and Mechanical Engineering,North China Electricity Power University,Beijing 102206,China) 【机构】 华北电力大学能源动力与机械工程学院；
【摘要】 通过建立数值模型进行编程计算,分析了锅炉过热器/再热器管道在不同的管道几何尺寸、烟气温度、1 蒸汽流量和温度下,各个界面热流密度的变化情况。通过回归分析得到了热流密度与管道内壁侧氧化层厚度和运行时间的关系表达式,即热流密度的评估关系式。 更多还原
【关键词】 动力机械工程； 锅炉过热器； 再热器； 热流密度； 氧化层 【基金】 中央高校基本科研业务费专项项目(09QX61)
3、锅炉过热器系统的动态仿真模型
【作者】 陈晓东； 王子才；
【Author】 Chen Xiaodong, W ang Zicai (Simulation Technology Research Center under the Harbin Institute of T echnology, Harbin, China, Post Code 150001) 【机构】 哈尔滨工业大学计算机信息网络中心!黑龙江哈尔滨150001；
【摘要】 鉴于机理模型很难再现锅炉过热器系统的复杂动态特性 ,本文利用机理模型为主导 ,动态神经网络在线修正 ,从而显著地提高了仿真模型的精度。仿真结果表明 ,此建模方法为复杂大系统的动态仿真提供了一个理想的建模途径。 更多还原
【关键词】 锅炉； 过热器； 仿真； 建模方法；
4、锅炉过热器爆漏原因的统计分析和预防措施
【作者】 李竹霞； 龙显淼； 童遂放； 夏昕；
【Author】 LI Zhu-xia,Senior Engnieer LONG Xian-miao TONG Sui-fang,Senior Engnieer XIA Xin,Senior Engnieer(Shanghai Institute of Work Safety Science,Shanghai 200233,China) 【机构】 上海市安全生产科学研究所；
【摘要】 以100余起公开报道的锅炉过热器爆漏事故案例进行统计分析为基础,将引起过热器爆漏的直接原因归纳为长期超温、短期超温、腐蚀、磨损和焊接缺陷,对产生事故的机理和主要原因进行了探讨和归类,认为运行管理不当是造成过热器爆漏的最重要方面。分析并提出了设计、安装、制造、检修和运行管理过程中对爆漏风险贡献最大的各单因素及其成因。针对造成爆漏的根本原因提出了预防措施,为锅炉的安全运行和合理检修提供了科学依据。 更多还原
【关键词】 锅炉过热器； 爆漏； 统计分析； 直接原因； 根本原因； 预防措施
5、烟气中灰粒对锅炉过热器、省煤器传热影响的研究
【作者】 高翔； 沈珞婵； 骆仲泱； 周劲松； 陈亚非； 李绚天； 倪明江； 岑可法；
【Author】 Gao Xiang(Hangzhou,Zhejiang University),Shen Luo-chan;Luo Zhong-yang;Zhou Jing-song; Chen Ya-fei; Li Xuan-tian; Ni Ming-jiang;Cen Ke-fa.【机构】 浙江大学；
【摘要】 采用模拟含尘烟气实验研究了烟气中含尘浓度、颗粒粒度和烟气速度等关键因素对锅炉过热器、省煤器传热的影响，得出了具有工程应用价值的经验关联式，并用于计算分析煤粉炉、两级分离的循环流化床锅炉和中温分离的循环流化床锅炉的过热器、省煤器等对流管束在考虑固体粒子影响作用后烟气侧的传热系数。通过传热机理分析，提出了可用于锅炉对流受热面设计的多相流传热模型，为循环流化床锅炉过热器和省煤器的设计计算提供了依据和方法。
【关键词】 锅炉； 过热器； 省煤器； 传热； 烟气； 灰粒；
四、《中国优秀博硕士学位论文全文数据库》（dlib.cnki.net） 列举出部分检索结果（含摘要）。
1、电站锅炉过热器寿命损耗在线监测系统的研究与开发
【作者】 王福珍；
2 【导师】 刘彤；
【作者基本信息】 华北电力大学（北京）， 热能工程， 2006， 硕士
【摘要】 随着电力工业的发展,电力设备装备水平不断得到提高,高参数、大容量火电机组的安全运行,尤其事故率较高的锅炉设备的安全、可靠运行已经成为一个亟待解决的问题。本文以火电厂锅炉过热器系统为研究对象,对电站锅炉过热器寿命损耗模式作了全面分析,研究了寿命评估技术,分析了过热器损伤危险部位,明确了监测点的位置,并针对典型的过热器系统进行了寿命损耗计算,在此基础上开发了电站锅炉过热器寿命损耗在线监测系统。该系统利用电厂SIS系统输入实时数据,运用delphi编程语言和SQL-Server数据库,采用基于数据库的服务器结构,编制了寿命在线监测的软件,实现实时跟踪过热器危险点外壁温度和过热器危险点寿命损耗在线计算。 更多还原
【关键词】 过热器； 高温蠕变； 危险点； 寿命损耗； 在线监测；
【网络出版投稿人】 华北电力大学（北京）
2、生物质锅炉过热器高温腐蚀研究
【作者】 李政； 【导师】 刘东雨；
【作者基本信息】 华北电力大学（北京）， 热能工程， 2010， 硕士
【摘要】 我国正在推广生物质发电技术,但过热器高温腐蚀的问题制约着生物质锅炉的发展。本文模拟生物质锅炉过热器区的积灰腐蚀条件,选取了三种腐蚀介质、三个温度条件对生物质锅炉常用管材T9
1、15CrMoG、12Cr1MoVG、20G、TP347进行了高温腐蚀实验研究。发现了基体渗氧腐蚀增厚现象,研究了基体增厚现象的机理。着重研究了腐蚀温度和腐蚀介质对12Cr1MoVG的影响。通过腐蚀减薄表征氧化腐蚀特性。利用扫描电镜和能谱仪对氧化腐蚀后试样表面和剖面进行分析,研究了12Cr1MoVG在不同温度不同腐蚀介质下的腐蚀类型、腐蚀产物和腐蚀形态,研究了12Cr1MoVG的活化氧化机理。最后用采集自生物质电厂的灰与渣在650℃下对T9
1、15CrMoG、12Cr1MoVG、20G、TP347进行了高温腐蚀实验,研究了试样在生物质灰与渣中的腐蚀类型、腐蚀产物和腐蚀形态。
【关键词】 生物质锅炉； 过热器； 高温腐蚀； 【网络出版投稿人】 华北电力大学（北京）
3、电站锅炉过热器和再热器超温爆管理论分析与计算方法的研究
【作者】 陈朝松； 【导师】 曹汉鼎；
【作者基本信息】 上海发电设备成套设计研究所， 热能工程， 2003， 硕士
【摘要】 针对电站锅炉过热器和再热器超温爆管，本文主要从蒸汽侧、烟气侧偏差及同屏热偏差三个方面进行了理论分析；在总结前阶段研究的基础上，对原有的壁温计算方法进行了一些新的改进，提出了分段计算模型，对壁温计算中涉及的角系数、辐射因数、曝光系数等主要参数进行了推导和修正，首次提出了用有限体积法求解辐射传递方程确定壁温计算中底部烟窗与前部烟窗辐射热负荷之比η值的新方法，并结合工程实际用VB6.0编制了比较通用的计算程序。作者利用所编写的计算程序和确定的η值，对德州电厂#
1、#
2、#
3、#4炉(300MW)和平圩电厂#1炉(600MW)的过热器或再热器壁温进行了实例计算，根据计算结果提出了相应的改造措施，其中德州电厂四台锅炉再热器根据所制定的方案进行了改造，改造后的实测数据与计算结果相一致，成功解决了再热器超温爆管问题。从而说明了该算法及程序的正确性和利用有限体积法求解辐射传递方程确定壁温计算中η值的可行性。
3 【关键词】 过热器； 再热器； 超温爆管； 热偏差； 壁温计算； 分段计算模型； 有限体积法； 【网络出版投稿人】 上海发电设备成套设计研究所
4、燃油锅炉过热器超温问题研究
【作者】 徐明成； 【导师】 张后雷；哈兵；
【作者基本信息】 南京理工大学， 动力工程， 2007， 硕士
【摘要】 本文针对中国石化扬子石化股份有限公司烯烃厂乙烯装置辅助燃油锅炉过热器在高负荷下容易出现超温现象,通过A、B炉对比试验研究,诊断出造成B炉出力不足和一级过热器超温的原因,找到影响锅炉正常运行的关键问题所在,即旋转式空气预热器的漏风增大是锅炉过热器超温的主要原因。化工装置高负荷生产时,需要锅炉高负荷发汽,为了多发汽,只有牺牲炉子的经济性,提高油压。油压的升高,意味着同负荷的情况下多投了油,此时一方面由于风量得不到保障,燃烧不充分,火焰长度变长,火焰中心上移;另一方面说明多投油则易导致炉膛水冷壁结垢,水冷壁吸热量减少,从而导致一级过热器超温。针对旋转式空气预热器的结构特点,提出优化运行参数和操作条件,不但对公司生产的稳定、高效、安全、节能等具有重要意义,而且可以为国内同类型锅炉的增效改造提供宝贵经验和必要的技术指导,因此具有重要的经济效益和一定的学术价值。 【关键词】 过热器； 超温； 空预器； 漏风； 对比； 【网络出版投稿人】 南京理工大学 【分类号】TK229.7
5、大型锅炉过热器、再热器炉内管子壁温的工程预测
【作者】 周细建； 【导师】 黄新元；
【作者基本信息】 山东大学， 热能工程， 2008， 硕士
【摘要】 电力工业是国民经济发展的先导产业,其发展程度一直是衡量社会文明和经济发达程度的标志。为满足现代社会对电力日益增长的需要以及对电站热电经济性和环保要求的不断提高,发展大容量高参数火电机组已势在必行。然而,由于设计制造、运行管理等诸多因素的影响,我国一大批大容量电站锅炉过热器、再热器相继发生超温爆管事故,严重影响了机组的安全、经济运行,因此开展对过热器、再热器超温爆管的研究具有非常重要的意义。本文首先介绍了国内外关于过热器、再热器超温爆管问题的研究现状,从理论上分析了引起热偏差及超温爆管的原因。在总结前人研究的基础上,对原有的单点壁温计算公式进行了发展和完善,提出了较为通用的壁温分段计算模型,对壁温计算中涉及的几个重要参数角系数、炉膛辐射因子等进行了计算公式的推导,避免了以前采用查曲线图带来的计算误差。利用建立的模型,并结合一台300MW锅炉后屏过热器进行了工质温度及壁温计算,对计算结果进行了图形化处理并做了相应分析,分析得出对于本锅炉后屏过热器各屏最外圈管右下弯头处为最容易发生超温爆管的危险部位,尤其以第8屏最外圈管右下弯头处壁温最高,原因主要有两点:第一,这些部位烟气温度高,热负荷大
【关键词】 过热器； 再热器； 热偏差； 超温； 爆管； 壁温； 【网络出版投稿人】 山东大学 【分类号】TK223.3
五、中国专利文献数据库(http://www.daodoc.com）
12 列举出部分检索结果（含摘要）。
1、Acceion number:
20133816749161 Title: Performance of alternate superheater materials in a potaium-rich recovery boiler environment
A.3; Frederick, Laurie A.3; Clemmons, Curtis4
Author affiliation:
1 Oak Ridge National Laboratory, Oak Ridge, TN, United States
2 SharpConsultant, Columbia, MD, United States
3 FPInnovations, Vancouver, BC, Canada
4 Recovery, MeadWestvaco Corporation, Covington, VA, United States
Source title:
Tappi Journal
Abbreviated source title:
Tappi J. Volume:
Iue:
7
Iue date:
July 2013
Publication year:
2013 Pages:
45-56
Language:
English ISSN:
07341415
CODEN:
TAJODT
Document type:
Journal article (JA)
Publisher:
TAPPI Pre, 15 Technology Parkway South, Norcro, GA 30092, United States
Abstract:
One method to significantly improve the efficiency of bioma-fired boilers is to increase the temperature and preure of the steam generated.However, this requires operating the superheater tubes at considerably higher temperatures than can be tolerated by conventional structural materials.The limiting temperature for conventional materials is primarily determined by corrosion of the superheater tubes that is promoted by interaction with the relatively low melting point deposits that accumulate on the tubes.An air-cooled deposit probe was used to collect samples of the deposits that accumulated on tubes in the superheater area of a recovery boiler in a mill proceing primarily hardwood.These deposits were found to be enriched in potaium.Subsequently, a corrosion probe containing multiple samples of nine different alloys was exposed for 2000 h in the same location of the superheater area of the same recovery boiler.The temperature of samples in the probe ranged from a low of about 400°C (752°F) to temperatures above 620°C (1148°F), compared to the boiler\'s estimated maximum tube temperature of 470°C (878°F).Following exposure, sections were taken from each of the 30 samples and examined using light microscopy and scanning electron microscopy.Results of the examination of these samples showed significant differences among the corrosion rates at temperatures 100°C above the current upper superheater tube temperature.A brief comparison is made to data from a parallel laboratory study.Application: This paper provides guidance on the selection of an alternate material for the highest temperature portion of the superheater tubes. Number of references:
Main heading:
Boilers
Controlled terms:
Boiler deposits Potaium Recovery Superheater tubes Conventional materials Limiting temperature Parallel laboratory Temperature and preures
13 Authors:
Keiser, James R.1 Email author keiserjr@ornl.gov.1; Sharp, W.B.A.2; Singbeil, Douglas
Claification code:
944 Moisture, Preure and Temperature, and Radiation Measuring Instruments 942 Electric and Electronic Measuring Instruments 741.1 Light/Optics 614.2 Steam Power Plant Equipment and Operation 549.1 Alkali Metals 531 Metallurgy and Metallography Database:
Compendex
Compilation and indexing terms, © 2013 Elsevier Inc.
2、Acceion number: 20134216847988 Title:Trends in fireside corrosion damage to superheaters in air and oxy-firing of coal/bioma Authors:
Huain, T.1 ; Syed, A.U.1; Simms, N.J.1 Author affiliation: 1 Centre for Energy and Resource Technology, Cranfield University,
Bedfordshire MK43 0AL, United Kingdom Corresponding author:
Huain, T.(t.huain@cranfield.ac.uk) Source title: Fuel Abbreviated source title: Fuel Volume: 113 Iue date: 2013 Publication year: 2013 Pages: 787-797 Language: English ISSN:
00162361 CODEN:
FUELAC Document type: Journal article (JA) Publisher: Elsevier Ltd, Langford Lane, Kidlington, Oxford, OX5 1GB, United Kingdom Abstract: This paper compares the laboratory-based fireside corrosion tests on superheater/reheater materials in simulated air-firing combustion conditions with oxy-firing combustion conditions (with hot gas recycling before flue gas de-sulphurisation).The gaseous combustion environment was calculated based on a specific co-firing ratio of CCP with Daw Mill coal.The fireside corrosion tests were carried out using the \"deposit recoat\" test method to simulate the damage anticipated in specific environments.A synthetic deposit (Na2 SO4:K2SO4:Fe2O 3 = 1.5:1.5:1 mol.) which has commonly been used in fireside corrosion screening trials and is a mix that forms alkali-iron tri-sulphate (identified in manyinvestigations as a cause of fireside corrosion) was used in these tests.The air-fired testswere carried out at temperatures of 600, 650 and 700 °C and oxyfired tests were carried out at temperatures of 600, 650, 700 and 750 °C to represent the superheater/ reheater metal temperatures anticipated in future power plants with and without synthetic deposits, with four candidate materials: T92, HR3C and 347HFG steels; nickel-based alloy 625 (alloy 625 was only tested with screening deposits).The progre of the samples during their exposures was measured using ma change methods.After the exposures, the samples were examined by SEM/EDX to characterise the damage.To quantify the metal damage, pre-exposure micrometre measurements were compared to the post-exposure image analyser measurements on sample cro-sections.The trends in corrosion damage in both air and oxy-firing conditions showed a \"bell-shaped\" curve, with the highest metal damage levels (peak) observed at 650 °C for air-firing and 700 °C for oxy-firing tests.However, at 600 and
14 650 °C similar damage levels were observed in both environments.The shift in peak corrosion damage in oxy-firing condition is believed to be the presence of higher levels of SOx, which stabilised the alkali-iron tri-sulphate compounds.Generally, in both air and oxy-firing conditions the mean metal damage was reduced with increasing the amount of Cr in the alloys.However, at the highest temperatures in both air-firing (700 °C) and oxy-firing conditions (750 °C) the metal damage of nickel based superalloy 625 was higher than HR3C.© 2013 The Authors.Published by Elsevier Ltd.All rights reserved.Number of references: 35 Main heading: Coal combustion Controlled terms:
Alloy steel Deposits Metals Co-firing Fireside corrosion 612 Engines 532 Metallurgical Furnaces 531.1 Metallurgy 521 Fuel Combustion and Flame Research 531 Metallurgy and Metallography DOI: 10.1016/j.fuel.2013.04.005 Database: Compendex
Compilation and indexing terms, © 2013 Elsevier Inc.
3、Acceion number:20130515973666
Title:Numerical analysis of stre and temperature coupled field for boiler superheater in thermal power plant
Authors:
Zhu, Rui1, 2 ; Ren, Jianxing1
Author affiliation:1 School of Energy and Environment Engineering, Shanghai University of Electric Power, Shanghai 200090, China
2 State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, China Corresponding author: Zhu, R.(zhurui_1981@163.com) Source title: Applied Mechanics and Materials Abbreviated source title: Appl.Mech.Mater. Volume: 241-244 Monograph title: Industrial Instrumentation and Control Systems Iue date: 2013
Publication year: 201
3Pages: 2139-2143 Language: English ISSN:
16609336 E-ISSN: 16627482 ISBN-13:
9783037855461 Document type: Conference article (CA) Conference name: 2012 International Conference on Measurement, Instrumentation and Automation, ICMIA 2012 Conference date: September 15, 2012 Finite element method Model structures Superheaters Thermoelectric power plants Couple field Distribution characteristics Highest temperature Power generation equipment Safety evaluations Stre field Structure design Thermal power plants Claification code: 921.6 Numerical Methods 641.1 Thermodynamics 951 Materials Science 421 Strength of Building Materials; Mechanical Properties 402.1 Industrial and Agricultural Buildings21, 2013 , Orlando, Florida Copyright 2013.NACE International Preview ABSTRACT
Currently, bioma is limited to low percentages of feedstock in UK co-fired power stations because of the severe corrosion which ensues and the resulting increase in shutdowns and maintenance costs.Recent field trials in power stations that use 100% bioma fuels indicate specialist coatings can provide protection of superheater tubes in these highly corrosive combustion environments.
This paper summarizes the results of several projects evaluating the use of thermal spray coatings and ceramic sealants to protect superheater tubes from the corrosion arising from the combustion of bioma fuels with high chlorine content, including attack by molten chloride salts.Several trials were carried out on uncoated samples under simulated bioma burning and molten salt environments to establish baseline corrosion.On site trials have shown that these coatings reduce oxidation and chlorination, double superheater tube life and allow plants to operate at higher temperatures with improved efficiency.The performance of the coatings correlates to coating composition, coating density and to the use of sealants which prevent ash-build up, solid particle erosion and may also reduce the diffusion rate of aggreive gaseous species through the coating.The performance of similar coatings exposed to laboratory tests simulating on-site corrosion is correlated to the bioma-fuelled power plant experience.The work has implications not only for bioma combustion, but also for co-firing and waste incineration plants.2.Publisher NACE International
Language English Document ID 2012-1638 Content Type Conference Paper Title: Fireside Corrosion And Carburization of Superheater Materials In Oxyfuel Combustion Authors Pekka Pohjanne, VTT Technical Research Centre of Finland; Satu Tuurna, VTT Technical Research Centre of Finland; Pertti Auerkari, VTT Technical Research Centre of Finland Source CORROSION 2012, March 11Paprican Source CORROSION 2010, March 1431, 2000 , Orlando, Fl Copyright 2000.NACE International Keywords Waste incinerator, weld overlay, high temperature corrosion Preview ABSTRACT
High temperature corrosion resistant superheater tubes are a critical component for the succe of future municipal waste incinerators designed to operate with a steam temperature of 500°C and 100 ata preure.In an effort to meet the challenge of producing such a component, 347SS tubes were overlaid with alloy 6M (Ni-20wt%Cr-lMo) using The Plasma Powder Welding (PPW) technique.PPW overlaid tubes were placed in the third superheater of a waste incnerator pilot plant for times up to 9,600 hours.The PPW overlaid tubes exhibited excellent corrosion resistance--similar to alloy 625 (Ni-21Cr-9Mo) tubes and better than HRllN (Fe- 30Cr-40Ni) tubes.This paper describes the PPW proce and discues the corrosion test results of the PPW overlaid superheater tubes tested in the pilot plant.
INTRODUCTION Currently, there is a national program to increase the energy efficiency of waste-to- energy plants in Japan from approximately 10% to 25%.In an effort to reach this goal, waste incinerators have been design to operate with a steam temperature of 500°C and a preure of 100 ata.A critical component of this new generation boiler is the superheater tube.The goal of this project was to develop a superheater tube with a fabricated cost similar to a tube made from alloy 825 (Fe-20Cr-40Ni) and high temperature corrosion resistance of a tube made from alloy 625 (Ni-21Cr-9Mo).Thus in an effort to
24 produce a corrosion resistant, cost-efficient superheater tube, solid tubes of 347SS were weld overlaid with two experimental alloys, placed in various locations within the superheater section of a pilot plant waste incinerator, and compared with the performance of solid 825 and 625 tubes.
The PPW proce uses a plasma arc for the heat source and a powder for the weld overlay filler material.Figure 1 shows a schematic diagram of the PPW proce.The plasma is generated between the tungusten electrode (negative) and the workpiece (positive).The consumable powder is fed through the nozzle at a proper angle and deposited into the plasma where it is melted and deposited onto the workpiece.Weld dilution is typically below 15% and the heat efficiency is high due to the tight focus of the arc.Since the filler material is a powder, materials such as carbon steel, Ni-base alloys, or ceramics can be applied to a given substrate.Furthermore, the proce can be automated and the deposition efficiency is high.Figure 2 shows an automated piece of equipment designed to weld overlay tubing over 6 meters in length using the PPW proce proce
TESTING PROCEDURE
Specifications of the superheater tubes produced for this project are shown in Figure 3, with the chemical compositions of the weld overlay alloys and the solid tube alloys given in Table 1.As shown in Table 1, the 6M and 5M powders contain similar amounts of Cr, Co, and Fe, however the 6M contains higher Mo, W, and le Nb, than the 5M.
The steam temperature and preure in the terminal section of the third superheater were approximately 500°C and 600 ata, respectively.Table 2 shows the temperature and the composition of the gas and ash obtained from this location.Two test samples of the 6M and 5M weld overlays, and HR11N and 625 solid tube alloys were installed in this section.After various times of plant operation, the remaining tube thickne was measured using ultrasonic testing, and the maximum wall thickne lo was calculated.
PILOT PLANT (1) TEST RESULTS AND DISCUSSION
Table 3 shows the maximum wall thickne lo exhibited by the 625 and HRllN solid tubes, and the 6M and 5M PPW overlaid tubes.As shown in this table, the maximum wall thickne lo of the 6M and 5M PPW overlaid tubes was le than.5.Publisher NACE International
Language English Document ID 96534 Content Type Conference Paper Title Sulfur Containing Sediments Influenced Wear of Superheater Tubes Authors Pavel Yoffe, Israel Electric Corp Ltd.Source CORROSION 96, March 24 - 29, 1996 , Denver, Co Copyright 1996.NACE International Keywords superheater tubes, sulfur containing sediment high temperature cofiosioq lqiler tube failure.Preview ABSTRACT The failed superheater tube was investigated at the point of failure and at a distance of 25 cm.At both of the cro two layers of sediment were detected The external one contained Na2SO4 and Na3VO3 in concentration relation 6.4:1 approximately.The internal layer that situated on the tube surface
25 consisted of V2O3 mainly (about 70% ) and Sodium pyrosulphates Na2SO3.xSO3.?The tube surface was covered with usual paive oxides such as Cr2O3, Fe2CrO4, and magnetite.In the faded section the last layer contained iron and chromium sulfides.Thinning of the wall was detected in both sections, but it was more evident in the failed section.
Thermodynamic and kinetic estimations of the results were carried out.The following failure mechanism was proposed: 1.At 460°C the pyrosulphate diociates with S(33 emanation.During S03 interaction with steel both paive oxides and iron sulfide are produced simultaneously.Sulfides damage the paive (protective ) film.2.h vicinity of partition the temperature increases and the structure of steel is changed S03 penetration along grain boundaries is poible, and it leads to embrittlement of the steel through sulphidization.3.The embrittled layer is stripped off by Ming ash deposit and collapsed paive film.Thinning of the tube is accelerated at such a region.So, sulfur containing sediment accelerates the wear of the tube.This acceleration is strong especially in the vicinity of the boiler walls.
INTRODUCTION
Corrosive activity of sulfur-rich sediment is well described in the literature.However, the mechanism of sulfphidization is discued relative to superalloys or high alloyed steels mainly.In the carbon.1ow alloyed steels case, the thermally influenced failures of creep and/or structrual degradation are considered to be their most eential subject
Superheater tube failure was occurred at some boilers of the same type at one of the Israel Electric Corporation power plants.In every case the tube failed in vicinity of the boiler wail.Neither sign of creep nor considerable microstructure degradation were detected The wall of the-tube was thinned and sulfur-riched sediment was presented on the external side of the tube.The boilers were fueled by oil containing sulfur.Accelerative influence of the sediment on the tube thinning was suspected
A laboratory investigation and thermodynamic and kinetic evaluation of the results were executed.The suspected role of the sediment was confirmed 十
一、检索结论（文献综述）
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