超超临界锅炉低NO_x燃烧优化对高温腐蚀的影响

为了评估低NO_x燃烧器升级后水冷壁高温腐蚀的可能性,对某超超临界锅炉炉内燃烧进行了数值模拟,并对SOFA(燃烬风)上摆的燃烧优化工况做了水冷壁贴壁气氛测试。结果表明:主燃烧区的上部和COFA、SOFA(分离式燃烬风喷嘴)之间的还原区发生高温腐蚀的可能性较大;SOFA上摆扩大了还原区,增加了高温腐蚀的可能性,还原区贴壁H_2S平均浓度沿着炉膛高度的增加而升高,为180~400μl/L;SOFA摆角的偏差使得局部H_2S浓度达到了800μl/L,进一步加剧了局部区域高温腐蚀的风险;强氧化强还原交替变动,使得SOFA以上区域(43.3~46.1 m)的高温腐蚀风险较典型还原区更为严重。在锅炉实际运行中,应尽可能权衡降低NO_x排放和控制高温腐蚀风险。     

670 MW对冲旋流燃烧锅炉防高温腐蚀试验研究

针对锅炉低氮燃烧改造后水冷壁近壁区发生高温腐蚀的问题,以某电厂670 MW超临界对冲旋流燃烧锅炉为研究对象,通过贴壁风系统改造结合燃烧优化调整试验,分析了贴壁风门开度、运行氧量、煤质变化等参数对水冷壁近壁区还原性气氛和炉内燃烧及运行参数的影响。结果表明：增加贴壁风系统后,水冷壁近壁区O2体积分数明显提高,CO体积分数平均值下降65.4%,H2S体积分数平均值下降53.2%,H2S平均值可控制在0.1×10-3以下,缓解高温腐蚀效果显著;高温腐蚀主要发生在高负荷工况,提高运行氧量有助于缓解高温腐蚀风险;增设贴壁风系统对锅炉氮氧化物排放量影响较小。     

350 MW对冲燃烧锅炉水冷壁高温腐蚀分析与治理

针对某发电有限公司2×350 MW对冲燃烧锅炉水冷壁高温腐蚀及结焦的问题进行分析,燃烧器烧损导致炉内动力场不均火焰刷墙、硫分含量高、二次风压低、吹灰器蒸汽吹损等是引起高温腐蚀的主要成因.通过贴壁风改造及后续的优化改造后,锅炉两侧墙的主燃烧区水冷壁得到保护,H2S和CO浓度明显降低,水冷壁高温腐蚀情况缓解.优化改造后20...     

四角切圆锅炉水冷壁高温腐蚀原因分析及对策

某电厂四角切圆锅炉进行低氮燃烧技术改造后,短时间内燃烧器与燃尽风之间的还原区水冷壁发生了严重的高温腐蚀,文中通过试验加数值模拟的方式分析了低氮改造后水冷壁高温腐蚀的原因,同时通过数值模拟的方法分析炉膛燃烧情况,并对在高温腐蚀严重的区域增加贴壁风改造方案进行模拟,通过分析贴壁风喷口对高温腐蚀区域烟气成分中的O_2、CO和H_2S的影响,为锅炉下一步改造提供指导意见。     

660MW机组锅炉SOFA风摆角对炉内高温腐蚀特性研究

在切圆锅炉中,SOFA(分级燃烧风)风的摆角调整会影响燃烧室内的气流流场和温度分布,从而影响高温腐蚀的发生情况。因此,应根据锅炉的设计参数选取适当的SOFA风摆角,以改善燃烧室内的流场和温度场,从源头上减少高温腐蚀的发生风险。本文选取660MW机组锅炉为研究对象,探索SOFA风摆角调整对炉内高温腐蚀特性的影响,实验结果表明：SOFA风摆角的调整对炉内还原性气体有明显的影响,若将锅炉SOFA风2号角摆角调整至正切最大,SOFA风1、3和4号角摆角摆动至反切最大,降低主燃烧器区域与燃尽风之间区域内局部还原性气体效果最佳,进而可以缓解局部的高温腐蚀。     

660 MW超临界对冲锅炉低氮改造后水冷壁高温腐蚀治理

针对超临界对冲燃烧锅炉在低氮改造后水冷壁两侧墙高温腐蚀加重的问题,分析了水冷壁高温腐蚀的原因及影响因素,全年平均St,ar约2. 78%,入炉煤硫分高、低氮改造后水冷壁近壁面还原性氛围浓是水冷壁高温腐蚀加剧的主要原因,针对该问题实施了锅炉侧墙贴壁风技术改造。通过贴壁风调整试验,找出了最佳贴壁风开度。贴壁风改造后,改善了侧墙还原性气氛,H2S体积分数能有效控制在200 ml/m3以下,缓解了水冷壁管高温腐蚀速率,大大降低了水冷壁腐蚀爆管泄漏事故风险和换管检修成本,有利于机组的安全、经济运行。     

超临界四角切圆燃烧锅炉运行方式对水冷壁高温腐蚀影响的试验研究

针对某630 MW超临界四角切圆燃烧锅炉水冷壁存在的高温腐蚀问题,对水冷壁近壁面烟气成分(O2、CO及H2S)进行了测试,分析了运行O2体积分数、煤粉细度、入炉煤含硫量、紧凑燃尽风(CCOFA)风量、分离燃尽风(SOFA)风量及周界风量等因素对水冷壁高温腐蚀及NOx排放特性的影响.结果表明:高温腐蚀发生区域表现出明显的强还原性气氛;增大运行O2体积分数,同时保证风量沿炉膛高度方向上的合理分配可减弱水冷壁近壁面还原性气氛;煤粉细度对水冷壁近壁面还原性气氛的影响较小;随着入炉煤含硫量的增加,水冷壁近壁面H2S体积分数增大,O2和CO体积分数则变化不大;较小的CCOFA风量及适当的SOFA风量有利于减轻水冷壁高温腐蚀;周界风量对主燃烧区下部壁面区域还原性气氛的影响较大,运行时应适当减少周界风量.     

锅炉高温腐蚀在线监测技术的研究

在试验室模拟某300 MW机组锅炉的高温腐蚀,对炉膛贴壁处烟气成分浓度和水冷壁高温腐蚀速率的相关性进行了试验研究.结果表明:在不同的气体配比下,高温腐蚀速率随CO浓度的提高呈抛物线增长;通过实时测量烟气中CO、O2、H2S和SO2等气体浓度,可实现炉膛高温腐蚀速率的在线监测.应用此研究结果在实炉中进行了热态试验,结果表明:在锅炉燃烧优化过程中,应监测炉膛水冷壁高温腐蚀速率,以确保机组安全.     

超超临界对冲燃烧锅炉水冷壁高温腐蚀燃烧调整技术研究

前后墙对冲旋流燃烧锅炉由于炉内燃烧组织方式和炉膛结构特点,水冷壁高温腐蚀主要发生在主燃区和还原区的左右两侧墙上,通过锅炉的摸底工况试验,诊断锅炉运行存在的问题,在此基础上进行燃烧优化调整,降低了水冷壁近壁区域烟气中还原性气体和腐蚀性气体的含量,以此来减缓水冷壁高温腐蚀的速率。     

530MW超临界机组对冲燃烧锅炉低氮燃烧贴壁风系统数值计算

为了有效预防水冷壁高温腐蚀、控制NO_x排放量,进行了某墙式对冲燃烧锅炉燃烧器低氮配风优化设计与改造,在主燃烧区加装"非对称矩形高速直流贴壁风"系统.结果表明:实测水冷壁贴壁气氛大幅改善,贴壁O_2体积分数明显升高,由0.3%升高至3.0%;炉膛前后墙贴壁烟温呈下降趋势,降幅100K左右,有效降低了水冷壁高温爆管风险.     

5种电站锅炉过热器用材料高温腐蚀试验研究

选取超超临界电站锅炉高温过热器用钢TempaloyAA一1、Super304H、TP347HFG、Tem—paloyA一3和HR3C为研究对象,在实验室真空炉中模拟实际烟气进行气相和气相一熔盐两相高温腐蚀试验．提出用腐蚀层厚度和迁移渗透深度之和作为衡量腐蚀速率的指标,分别得到5种钢的抗气相及气相一熔盐两相高温腐蚀能力．结果表明：5种过热器材料抗气相高温腐蚀的能力都很强;TempaloyA一3、TP347HFG、Super304H、TempaloyAA一1和HR3C5种钢的抗气相一熔盐腐蚀的能力依次增强;过热器材料的腐蚀主要是气相一熔盐两相腐蚀．     

Tubular Type Heat Flux Meter for Monitoring Internal Scale Deposits in Large Steam Boilers

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.     

某200MW四角切圆锅炉燃烧器改造降低NO_x数值模拟

针对国内某电厂200MW四角切圆锅炉NOx排放量较高,结渣严重的问题,利用CFD软件平台,采用数值模拟方法对其改造前后炉内燃烧过程进行研究。计算结果表明:由于附壁射流的作用,使得高温区集中在炉膛中部,有效地防止了锅炉结渣;改造后炉内有比常规燃烧方式锅炉更大的还原气氛区域,抑制了NOx的产生,使其排放降低34.6%。改造后的计算结果与试验相符的较好,所以此次数值模拟为锅炉设计、改造和运行提供理论依据。     

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.     

300 MW墙式切圆锅炉水冷壁超温的数值模拟与燃烧优化

某300 MW四墙切圆燃烧锅炉在实际运行过程中一直存在着燃烧器区域的火焰刷墙与高温腐蚀现象,导致燃烧器区域水冷壁易超温,严重影响机组的安全运行.通过现场试验与数值模拟,分析了产生以上问题的原因,并针对性地提出了相应的燃烧器改造与优化方案.结果表明:造成水冷壁超温与高温腐蚀的主要原因是燃烧时火焰产生的切圆过大、火焰气流距...     

600MW超临界对冲燃烧锅炉CO和NOx排放特性的研究

采用现场试验研究和数值模拟的方法对布置前后墙对冲燃烧器的某600Mw超临界锅炉CO和NO,的排放特性进行了研究．结果表明：锅炉尾部烟气中CO质量浓度为500～2500mg／m3,当主燃烧区过量空气系数a,为0．86～0．90时,高于该锅炉低NO。排放的设计过量空气系数（0．80）,对应的燃尽风占二次风的比例约为27％～32％,NOx排放质量浓度出现拐点;锅炉的NOx排放特性与HT—NR3燃烧器的低NOx设计有关,并与该锅炉的CO排放特性呈负相关关系;在负荷为600Mw和总风量一定的工况下,当燃尽风比例从32％提高至49％时,CO排放质量浓度显著下降,飞灰可燃物浓度降低,氧气量对CO和NOx排放的影响明显减弱,但NOx排放质量浓度升高,主燃烧区侧墙高温腐蚀的风险增大．     

复合分级燃烧对四角切圆锅炉NOx排放特性的影响

采用复合分级燃烧技术对某一燃用褐煤的四角切圆600 MW锅炉进行了低氮燃烧改造。这种复合分级燃烧技术主要是将水平浓淡燃烧技术,燃尽风技术,偏置二次风技术等有机结合起来。改造后,对一次风量,辅助风的配风方式,燃尽风率,燃尽风配风方式,锅炉过量空气系数等对锅炉NOx排放特性的影响进行了研究。在改造和燃烧优化后,锅炉实现了在高效燃烧的同时NOx浓度大幅降低。     

Investigation on high temperature corrosion of water-cooled wall tubes at a 300 MW boiler

Because of the updated requirement on ultra-low NOx emission (<50 mg/Nm³), most of Chinese coal-fired boilers have to be operated at a low NOx combustion mode. However, for high-sulfur coal, water-cooled wall tubes probably suffer severe corrosion in such a strong reduction atmosphere. This work aims to investigate the high temperature corrosion behavior of water-cooled wall tubes inside a 300 MW boiler unit. A short length of corroded water-cooled wall tube was cut down and was analyzed by various characterization methods to further figure out the detailed corrosion mechanism. The typical corrosion products can be distinguished by blue, black and pale-green. Results showed that blue and black color products were mainly consisted of iron sulfides and iron oxides while the pale-green ones were identified as zinc sulfide. Along the radial direction, a layered structure of corrosion products can be observed. The formation of inner layer resulted from the reaction between iron oxide and hydrogen sulfide. The sulfur element displays a gradual increase trend while the Fe element gives out an opposite trend along the radially outward direction. The intermediate layer comes from the fly ash deposition and the outer layer is formed via condensation and deposition of ferrous sulfide gas on the water-cooled wall. The corrosion in this power plant is typical sulfide type for large amounts of Fe and S element were found in the corrosion products.     

双区燃烧技术应用于降低NO_x的数值模拟研究

双区燃烧是降低Nox排放,防止炉内结渣的一项新技术.利用CFD软件平台,采用数值模拟方法对其某电厂200 mm四角切圆锅炉改造前后炉内燃烧过程进行研究.计算结果表明:采用双区燃烧技术使炉膛中形成了温度,组分和颗粒相参数显著不同的中心区和近壁区.由于附壁射流的作用,使得高温区集中在炉膛中部,有效的防止了锅炉结渣;改造后炉内有比常规燃烧方式锅炉更大的还原气氛区域,抑制了Nox的产生,使其排放降低34.6 %.     

大型锅炉水冷壁高温腐蚀探讨

从理论和实际出发 ,阐述了水冷壁发生高温腐蚀的类型 ,大型贫煤锅炉水冷壁发生高温腐蚀的原因 ,四角切圆燃烧方式防止高温腐蚀的措施。针对石洞口电厂锅炉改造 ,提出防止高温腐蚀的具体措施。