Stability of protective oxide films in waste incineration environment—solubility measurement of oxides in molten chlorides

Solubility measurements of several oxides in molten NaCl-KCl and NaCl-KCl-Na₂SO₄-K₂SO₄ were conducted in three different levels of basicity. The dissolution behavior of the oxides showed almost the same tendency as that shown by the dissolution behavior of the oxides in molten Na₂SO₄ in literature. In a waste incineration environment, a protective Cr₂O₃ film easily dissolves in molten chlorides as CrO₄²⁻ because pO²⁻ of the molten chlorides tends to have a small value due to the effect of water vapor contained in the combustion gas. From the result of the solubility measurement, the addition of molybdenum and/or silicon was expected to improve the corrosion resistance of alloys. Laboratory corrosion tests confirmed this expectation. However, the scale analysis suggested that the effect of molybdenum could not be explained completely by only the mechanism derived from the result of the solubility measurement.     

二次过热器炉管的腐蚀损伤分析与表征

采用金相检验、扫描电镜、三维视频系统及能谱分析等方法，对350MW火力发电机组经13万h运行后二次过热器炉管内表面严重腐蚀损伤进行了检测与表征。结果表明，该炉管内表面的损伤主要是由水中的氯离子及溶解氧作用下引起的点腐蚀所致，为此提出了相应的预防措施。     

Prediction-based feedforward control of superheated steam temperature of a power plant

A novel feedforward-feedback control scheme for superheater steam temperature in accordance with industrial requirements is proposed. The novelty lies in the design of the feedforward compensator (FFC), of which the performance relies on accurately predicting the values of disturbance variables. The heat influx from the flue gas and the superheater inlet steam temperature were identified as two major disturbances, in addition to the change in the power load. Two FFCs were designed to accommodate the individual disturbances. Because the flue gas state is difficult to measure, the superheater pipe temperature was chosen as a new variable to represent the flue gas state and estimated using steam temperature measurements. Both FFCs computed the feedforward inputs based on the predicted values of the disturbance variables. The prediction accuracies of the FFCs were assessed separately using field-test data, and the performance of the resulting feedforward-feedback controller was investigated through numerical simulations. As a consequence, the IAE (integrated absolute error) under the proposed control scheme was observed to be decreased by 25–38% for three load change scenarios compared to that under the existing feedback controller.     

SZS8-1.25/280-Q(Y)型锅炉的开发和设计

介绍了SZS8-1.25/280-Q(Y)型锅炉的开发过程，以及该锅炉的结构特点。     

电厂三级过热器弯管失效分析

用金相、电镜、光谱分析等手段对三级过热器弯管失效进行了分析。结果表明,晶界处有铬的化合物所析出,具有晶间腐蚀倾向;材质夹杂和多且颗粒较大;奥氏体晶料不均匀,有严重混晶,上述综合因素导致弯管断裂。     

BP-1025型锅炉二级过热器腐蚀原因分析与防腐措施

对太原第一热电厂ＢＰ—１０２５型锅炉二级过热器大面积腐蚀,造成二级过热器频繁爆管泄漏的原因进行了分析,并采取了相应措施。     

A 7 year long measurement period investigating the correlation of corrosion,deposit and fuel in a biomass fired circulated fluidized bed boiler

The present investigation involves a unique, 7 year (2001–2007) long study of corrosion and deposits on superheater tubes in a biomass fired circulated fluidized bed boiler. These measurements are correlated against the different fuels used over this period. In the earlier years, the boiler was run with a mixture of different biomass fuels and peat. In later years, recycled wood was introduced into the fuel mix. The deposit growth rate approximately doubled when the recycled wood content of the fuel was increased to 10–20%. Small amounts of chlorine and zinc were found both in the recycled wood and in the deposit layer. These elements together with alkali metals from the biomass, have the potential to form sticky compounds that increase the deposit growth rate. The corrosion rate of the superheater tubes varied over the study period. A number of possible explanations for this phenomenon are discussed.     

Estimation of oxide scale growth and temperature increase of high (9–12%) chromium martensitic steels of superheater tubes

The improved ferritic steels that have very good creep strength such as grades 91 and 92 have been widely used for power plant applications. For example, a chromium–molybdenum–vanadium steel tube (SA213-T91) has been available in the market for two decades. The SA213-T91 material has better high temperature strength and oxidation resistance than those of the more widely used materials such as T11 and T22. In this paper, estimations of the oxide scale growth and temperature increase of 9–12% Cr martensitic steels of superheater tubes are carried out using an incremental procedure, utilizing the finite element simulations and the relation between the Larson Miller Parameter (LMP) and the scale thickness over a period of time. In order to show the superiority of T91 steels over T22 steels, two different steam temperatures are considered in the models for comparisons. The estimations showed as expected that the oxide scale growth and temperature increase of the 9–12% Cr steels were significantly lower compared to those of 2.25% Cr steels.     

论锅炉过热器爆管的机理和成因

锅炉过热器爆管，对锅炉寿命和制备工艺都是一种摧残和破坏。本文针对导致爆管的机理和成因，从运行，管理及安装检修质量等方面进行了比较详细的分析和研究，并提出防范措施。     

锅炉过热器管爆裂原因分析

针对某热电厂4号锅炉12CrlMoV钢过热器管的爆裂破坏,进行了宏观形貌、化学成分、金相组织、扫描电镜等的分析。结果表明,炉管爆裂的原因是炉内局部温度过高,该处炉管长期过热,管壁组织珠光体球化达到5级．晶界出现蠕变裂纹,导致炉管强度降低所致。