过热器、再热器F/A异种钢焊接接头缺陷与对策

电站锅炉过热器、再热器管排常用的材料有15CrMo、12Cr1MoV、钢102、T22、T91,TP304H,TP347H、TP347HFG、Super304H、HR3C等，其极限工作温度见表1。     

锅炉奥氏体不锈钢在模拟煤灰和高硫烟气环境中腐蚀行为的研究

在模拟煤灰和高硫烟气环境中研究了3种锅炉用奥氏体不锈钢TP347HFG、Super304H和HR3C在650℃的高温腐蚀行为及腐蚀机理.通过不连续称重法测量试样质量的变化,采用扫描电子显微镜(SEM)、能谱分析(EDS)和X-射线衍射(XRD)等分析方法研究腐蚀产物的形貌、元素分布和腐蚀产物物相.结果表明:经500h高温腐蚀后,3种合金均出现腐蚀损失,但HR3C腐蚀程度较TP347HFG和Super304H轻;TP347HFG和Super304H合金腐蚀产物分层生长且剥落严重,外层氧化膜为Fe_2O_3,内层为Cr_2O_3层及大量内硫化物;HR3C表面形成了保护性的(Cr,Fe)_2O_3氧化膜,未见明显的剥落现象.     

超超临界锅炉高温受热面用管的选材分析研究

为综合比较超超临界锅炉高温受热面管材料Super304H和HR3C的性能,对高温受热面管的选材提供支撑,从原材料力学性能、高温抗氧化性能等方面对Super304H钢和HR3C钢进行对比分析,并结合2种材料的试验室蒸汽氧化试验数据,以及机组运行服役38 000 h和60 000 h后内表面氧化及外表面腐蚀的状况开展综合评价。结果表明：Super304H钢管内壁喷丸后的抗蒸汽氧化效果优于HR3C钢管,同时Super304H钢管和HR3C钢管外壁均具备足够的抗烟气腐蚀能力,能够满足现有锅炉的使用要求。建议高参数超超临界机组的受热面材料优先选用Super304H内壁喷丸管,可逐步替代HR3C钢管。     

生物质锅炉过热器管的高温氯腐蚀

为了选择合适的生物质发电锅炉过热器管材以减少高温氯腐蚀,模拟生物质锅炉过热器区的气相条,对管材TP347H和CT45在12%CO_2-5%O_2-0.05%HCl-N_2气氛中的高温氯腐蚀试验进行了研究。     

超超临界锅炉用钢SUPER304H、TP347HFG和HR3C长期蠕变特性和微观组织研究

SUPER304H（18Cr-9Ni-3Cu—Nb—N，ASME CC2328）和TP347HFG（18Cr-12 Ni—Nb，ASME SA213）钢种，已经成功研制并用于制造高强度、高抗蒸汽氧化性能的钢管。SUPER304H在600℃最长蠕变时间为85，426小时和TP347HFG在700℃最长蠕变时间为55，858小时，这充分证明了其具有稳定的强度和微观组织，与其他传统的奥氏体不锈钢相比，即使在微观组织中发现含有很少量的σ相，但并没有观察到其它脆性相。HR3C（25Cr-20Ni—Nb—N，ASME CC2115）也已研制并用于具有高强度和高抗腐蚀性能的钢管。该钢管可应用于蒸汽温度为600℃左右的超超临界锅炉的易腐蚀部件。HR3C在700℃、69MPa的最长蠕变时间为88，362小时，这证明在600—800％它具有相当高的蠕变强度和稳定的微观组织。自1991年以来，这三种钢管已经作为过热器和再热器管安装在Eddystone三号超超临界炉上，而且经过长期服役后，割管取下进行微观组织研究。本文描述了这三种钢管的最新长时蠕变特性和长期时效后微观组织的变化。目前世界上已经将这_一种钢管作为标准材料成功用作新刊榴超临界锅炉的讨热器和再热器管。     

Super304H焊接工艺试验研究

本文介绍了Super304H同种钢、Super304H与SA-213TP347H及SA-213T91异种钢焊接性能试验，并通过试验确定较为合理的焊接及热处理规范。该钢用于我国超临界及超超临界锅炉机组具有很大的潜力。     

Super304H不锈钢锅炉管评述

日本研制开发的、用于超(超)临界锅炉机组的新型Super304H奥氏体不锈钢管,在650℃的抗氧化性优于目前常用的SA-213TP304H和SA-213TP347H,相同条件下的氧化腐蚀深度仅为SA-213TP304H的一半,为SA-213TP347H的67%.试验证明,其焊接接头力学性能符合蒸汽锅炉安全技术监察规程和ASME相应规范要求.对该负的性能及特点进行较为详尽地评述介绍.最后的综合分析认为:该钢种作为我国超(超)临界锅炉机组的过热器和再热器管子材料是合适的.     

国外超（超）临界锅炉用高温高压钢管材料特性及应用介绍

本文对国外超(超)临界机组锅炉和大型循环流化床锅炉用高温高压锅炉钢管15NiCuMoNb5-6-4、T23／P23(HCM2S)、T24(7CrMoVTiB10-10)、T91／P91、T92／P92(NF616)、TP304H、TP347H、HCM12A(T122)、SUPER304H、TP347HFG、火SUS310JITB和NF709等的特性，如化学成分、金相组织、常温力学性能、许用应力、使用温度、抗氧化性能、抗腐蚀性等进行了介绍，并阐明了这些材料在国内外的应用情况和在我国(厂)的应用前景，以期对调整我国电站锅炉材料的使用方式以及进一步推动这些材料的国产化进程起到抛砖引玉的作用。     

垃圾焚烧环境中典型材料的腐蚀性研究

模拟垃圾焚烧炉内环境,在550℃条件下,开展了T91、TP347H、TP347HFG、TP310S、UNS 6625等材料的腐蚀实验研究。采用减重法和壁厚法分别计算腐蚀速率,利用光学显微镜和配有能谱仪的扫描电镜对试样件腐蚀后的形貌结构、元素含量进行分析。结果表明:垃圾焚烧炉中积灰腐蚀严重,可采用改善受热面清洁状况及优化受热面材质的方法减轻;在相同条件下,镍基合金材料UNS 6625由于其氧化物在氯化物熔盐中的热稳定性好,腐蚀速率小,耐腐蚀性好,可用于垃圾焚烧炉中的高温部位;不锈钢材料表面的晶粒细化后,能有效改善材料的抗腐蚀性能;在工程现场,壁厚法仅适用于无晶间腐蚀的材料,不适用于不锈钢材料;不锈钢材料的腐蚀情况判断应将晶间腐蚀考虑在内,并结合SEM-EDS分析。     

HR3C和Super304H不锈钢管子的固溶化热处理试验研究

通过分析HR3C和Super304H不锈钢管子在不同热处理条件下,管子的晶间腐蚀、硬度及机械性能的试验参数,证明HR3C可采用与Super304H相同的固溶化热处理温度进行热处理,并且在管子相对弯曲半径R/D≥31/3时,HR3C和Super304H可免除固溶化热处理.     

Effects of fuel composition and temperature on fireside corrosion resistance of materials for advanced ultrasupercritical coal fired power plants

Abstract

The fireside corrosion resistance of candidate materials for the waterwalls and superheater/reheater sections of ultrasupercritical coal fired boilers have been evaluated through field testing as part of a programme cosponsored by the US Department of Energy and the Ohio Coal Development Office. The materials tested include high strength ferritic steels (SAVE12, P92, HCM12A), austenitic stainless steels (Super304H, 347HFG, HR3C), and high nickel alloys (Haynes 230, CCA617, INCONEL 740, HR6W). Protective coatings (weld overlays, diffusion coatings, laser claddings) that may be required to mitigate corrosion were also evaluated. The trials were based on previous laboratory evaluations under synthesised coal ash and flue gas conditions typical of three North American coals at temperatures ranging from 455 to 595°C for waterwall materials, while superheat/reheat materials were tested at 650–870°C. Promising materials from the laboratory tests were assembled on air cooled, retractable corrosion probes for testing in utility boilers. The probes were designed to maintain metal temperatures using multiple zones, ranging from 650 to 870°C. Three utility boilers, equipped with low NO_x burners, were identified that have adequate flue gas temperatures and represent each of the three coal types. New fireside corrosion probe results are presented for mid-western and western coal types, after approximately one year of exposure in the field. Visual examination of samples from the mid-western utility site indicated minimal evidence of significant wall loss for any of the tested materials. Samples removed from the western utility site indicated evidence of wall loss for some tested materials. Further evaluation and quantification of total metal wastage through wall thickness measurements and metallographic examination of subsurface penetration is being undertaken.     

Long term creep properties and microstructure of SUPER304H,TP347HFG and HR3C for A-USC boilers

Abstract

SUPER304H (18Cr–9Ni–3Cu–Nb–N; ASME CC2328) and TP347HFG (18Cr–12Ni–Nb; ASME SA213) have been developed for high strength oxidation resistant steel tubes to operate at high steam temperatures and pressures. The longest creep rupture tests performed to date (600°C for 85 426 h for SUPER304H; 700°C for 55 858 h for TP347HFG) showed that the stable strength and microstructure were retained, with very little formation of σ-phase compared with conventional austenitic stainless steels and no other brittle phases. The alloy HR3C (25Cr–20Ni–Nb–N; ASME CC2115) has been developed for the high strength and high corrosion resistant steel tubes used in recent ultrasupercritical (USC) boilers with steam temperatures of ～600°C. The longest creep test conducted to date (700°C, 69 MPa for 88 362 h) confirmed a stable creep strength and microstructure at 600–800°C. Superheater and reheater tubes of these alloys installed in the Eddystone No.1 USC power plant since 1991 have been removed and investigated. Updated long term creep rupture properties of the steels and microstructural changes during service are reported. Three steel tubes have been successfully applied as standard materials for superheater and reheater tubes in newly built USC boilers.     

1025t/h直流锅炉前屏过热器夹持管爆漏原因分析

介绍材料为TP3 0 4H的 1 0 2 5t/h锅炉前屏过热器夹持管晶间应力腐蚀裂纹是爆漏的主要原因 ,证明了夹持管材料更换成TP3 47H钢管是解决爆漏问题的关键     

Creep properties and microstructural evolution of austenitic TEMPALOY steels

The steam parameters in the new high efficiency fossil fuel power plants are continuously increasing, requiring new advanced materials with enhanced creep strength able to operate on the most severe temperature and pressure conditions. For super-heater and re-heater applications, TEMPALOY AA-1 steel, an evolution of 18Cr10NiNbTi alloy, has been developed through the addition of 3%Cu and B, significantly enhancing the creep resistance, while offering typical corrosion properties of 18%Cr steels. This paper describes Tenaris’ tubular products in the field of austenitic grades for applications in Ultra Super Critical power plants: the production route and the main microstructural and mechanical properties of TEMPALOY AA-1 and TEMPALOY A-3 steels, including the effect of shot blasting on steam-oxidation resistance, their creep–rupture properties and their microstructural evolution during temperature exposure are presented.     

High-temperature corrosion of water-wall tubes in oxy-combustion atmosphere

Oxy-combustion is one of the most promising technology for CO₂ capture in coal-fired power plants. However, under oxy-combustion conditions, the concentrations of acid gas species are significantly increased due to the introduction of the flue gas recycle, which aggravates the high-temperature corrosion of heat exchanger materials in boilers. In this study, the early-stage high-temperature corrosion (0–16 h) of two representative water-wall tube materials (20G, 12Cr1MoV) is experimentally tested in a lab-scale furnace with the simulated oxy-combustion atmosphere. The effects of material, temperature, CO₂, H₂O, SO₂, H₂S and CO atmospheres on high-temperature corrosion behaviors is investigated. The micro-morphologies and compositions of corrosion layers are characterized by scanning electron microscope with energy dispersive X-ray spectra (SEM-EDS) and X-ray diffraction (XRD). Kinetic analysis shows that the high concentration of CO₂ accelerates high-temperature corrosion of water wall materials. In the simulated oxy-fuel combustion atmosphere (CO₂/O₂/SO₂), the mass gain rate can be enhanced by 10%–30% compared to the conventional air combustion atmosphere (N₂/O₂/SO₂), and the major composition of oxide scale is magnetite. In a reducing oxy-fuel atmosphere (CO₂/CO/SO₂/H₂S), the major components of oxide scale are magnetite and ferrous sulfide. The high concentration of moisture in the atmosphere accelerated the corrosion rate by 10–30%. For both model alloys, the corrosion kinetics obey the parabolic law. Water-wall tube material 12Cr1MoV appears superiority in corrosion resistance compared with 20G material.     

Corrosion behavior of candidate heat exchanger materials in oxidizing and reducing gases relevant to oxyfuel power plants

In the present paper, the oxidation behavior of potentially suitable construction materials for heat exchanging components in coal fired power plants was studied in the temperature range 550–700 °C. The selected materials (low alloy steel 13CrMo44, martensitic steel P92, austenitic steel S304HCu and Ni-base alloy 617) were exposed in a simulated atmosphere typical for oxyfuel combustion and the results were compared with the behavior in a test gas simulating oxyfuel gas with addition of CO, thus simulating locally occurring reducing operating conditions which may happen due to incomplete combustion. The oxidation/corrosion behavior was studied by gravimetry in combination with a number of characterization methods such as optical microscopy, scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX) and glow discharge optical emission spectroscopy (GDOES). For the low alloy steel and P92 only minor differences in oxidation rates between the different environments were found. For S304HCu generally smaller corrosion rates were found in the reducing gas, whereas for alloy 617 the effect of gas composition depended on temperature. The obtained results are interpreted on the basis of thermodynamic considerations comparing equilibrium activities of the main species in the gas atmospheres with the thermodynamic stabilities of various possible corrosion products.     

Corrosion of construction materials of separator in molten carbonates of alkali metals

The mitigation of steels and alloys corrosion is one of the great challenges for application of high-temperature devices in contact with molten salts. The current research estimates corrosion resistance of the following construction materials: Crofer APU 22, austenitic steel 12Cr18Ni10Ti and two types of austenitic nickel-chromium alloy: CrNi78Ti, CrNi78Ti + 5% wt. W. The measurements are performed by exposition of samples within 24 h in the molten mixture of carbonates of lithium and potassium at 650 °C. The rates and mechanism of materials corrosion under these conditions are determined. The process occurring on the surface while contact of the materials and steels with carbonate melt are investigated.Accurate quantitative data on materials interaction with alkali carbonate melt have been obtained by gravimetrical and physico-chemical methods. The high-temperature corrosion of Fe and Ni austenitic materials has turned dramatically different from both their low-temperature corrosion and each other. There are mixed passivating oxide films on the surface of the only iron-based materials.In addition, the resulting layers of corrosion products are well bonded to the substrate and have protective properties and can be used as protective coatings in molten salts of other compositions, including alkali metal fluorides.     

液幕状气液两相流流动特性的实验研究

提出了一种名为“液幕状气液两相流”的新流型。对液幕状气液两相流的流动特性进行了实验研究,着重研究液幕状气液两相流的床层高度和阻力特性以及气相和液相流动速度之间的关系,得到了当量床层高度、实际床层高度以及液幕床层阻力系数计算的关联式。这些关联式为液幕状气液两相流的研究提供了基础性的科学实验数据。     

Corrosion resistance of pyrolytic graphite in LiCl-KCl-UCl3 molten salt for pyrochemical reprocessing application

Pyrolytic graphite (PyG) is a highly oriented, dense and crystalline form of graphite, which exhibits superior air oxidation resistance, corrosion resistance, and favourable mechanical, thermal, and electrical properties compared to conventional graphite materials. It is proposed as the material of construction for high-temperature molten LiCl-KCl for pyrochemical reprocessing of metallic fuel. In the present study, long-term corrosion behaviour of PyG in LiCl-KCl molten salt with 5?wt-% UCl₃ was evaluated by immersion studies at 873?K for 2000?h, under inert argon atmosphere. Characterisation of PyG before and after molten salt exposure was carried out using X-ray diffraction technique, scanning electron microscope with energy dispersive spectroscopy, laser Raman spectroscopy and X-ray photo-electron spectroscopy. The results revealed the superior corrosion resistance and excellent phase stability of PyG with negligible weight change and no appreciable change in the surface chemistry and morphology up to the exposure time of 2000 h.