Finding of Gray Points on the Surface of the Sn-Fe Alloy Layer and Its Effects on the Corrosion Resistance of the Alloy Layer

After removing tin coating of tinplates offered by some steel works, we discovered massive, highly disperse gray points outspreading along rolling direction on the surface of the alloy layer. Morphology of the alloy layer was observed by scanning electron microscope (SEM), and many cavities of the alloy layer were found out in the gray point. After analyzing the composition of the alloy layer, we found that content of Fe in the gray points was more than that in the normal alloy layer. Moreover, corrosion resistance of the alloy layer declines with increase of amount of gray points. In addition, the hot-humidity testing was carried out for some plates whose surface has many gray points. After 14 days, there were many rust points occurring in the edge of gray points and in the small gray points. The morphology of rust points was observed by atomic force microscope (AFM). The reason why rust points generated in the edge of gray points and in the small gray points was discussed.

Design calculation of porous ceramics tube type dew point indirect evaporative cooler

To improve the wall surface hydrophilicity of a tube type indirect evaporative cooler,a new method adopting porous ceramics is proposed.This method realizes the combination of porous ceramics and the evaporative cooling technique.The design calculation of the porous ceramics tube type dew point indirect evaporative cooler are carried out from such aspects as the volumes and status parameters of the primary and secondary air,the cooler structure,the heat transfer of the solid porous ceramic tubes and the resistance of the cooler.The calculation results show that the design is reasonable.Finally,based on the design calculation,the porous ceramics tube type dew point indirect evaporative cooler is successfully manufactured.

Estimating Daily Dew Point Temperature Based on Local and Cross-StationMeteorological Data Using CatBoost Algorithm

Accurate estimation of dew point temperature(Tdew)plays a very important role in the fields of water resource management,agricultural engineering,climatology and energy utilization.However,there are few studies on the applicability of local Tdew algorithms at regional scales.This study evaluated the performance of a new machine learning algorithm,i.e.,gradient boosting on decision trees with categorical features support(Cat Boost)to estimate daily Tdew using limited local and cross-station meteorological data.The random forests(RF)algorithm was also assessed for comparison.Daily meteorological data from 2016 to 2019,including maximum,minimum and average temperature(Tmax,Tmin and Tmean),maximum,minimum and average relative humidity(RHmax,RHmin and RHmean),maximum,minimum and average global solar radiation(Rsmax,Rsmin and Rsmean)from three weather stations in Hunan of China were used to evaluate the CatBoost and RF algorithms.The results showed that both algorithms achieved satisfactory estimation accuracy at the target stations(on average RMSE=1.020℃,R^(2)=0.969,MAE=0.718℃and NRMSE=0.087)in the absence of complete meteorological parameters(with only temperature data as input).The Cat Boost algorithm(on average RMSE=1.900℃and R^(2)=0.835)was better than the RF algorithm(on average RMSE=2.214℃andR^(2)=0.828).The accuracy and stability of the CatBoost and RF algorithms were positively correlated with the number of input parameters,and the three-parameter algorithms achieved higher estimation accuracy than the two-parameter algorithms.The developed methodology is helpful to predict Tdew at regional scale.

NIS One-Temperature Dew-Point Generator Operating in the Ranae -50℃ to 0 ℃

This paper describes construction and characterization of a dew/frost -point generator developed at national institute for standards. It is intended to operate in the range from -50 ℃to 0 ℃. The air flows through a saturator controlled by a regulated flow meter. The reference dew/frost -point temperature was measured by standard platinum resistance thermometer （SPRT） connected to a resistance bridge. A comparative study between the saturator temperature of the new generator measured by SPRT and the dew/frost-point temperature of a calibrated chilled-mirror hygrometer was conducted. It helped to determine the uncertainty of saturator; this uncertainty was found to be between ±0.06℃ to -4- 0.15℃ at confidence limit of 95%.Several experiments were carried out in the mentioned range. Obtained results gave the confidence that NIS generator could be used as a primary humid air generator.

Experiment and Analysis on Flue Gas Low Temperature Corrosion Monitoring

Thermal loss of exhaust flue gas accounts for the largest proportion of the total boiler thermal loss. Nowadays in China, the exhaust gas temperature in many thermal power plants is much higher than the designed value, thus, the recycle and reuse of the waste heat of tail flue gas is necessary. However, lower exhaust gas temperature will aggravate low temperature corrosion of the tail heating surface, which also causes huge economic losses. In order to solve this problem, this paper designs a monitoring experiment platform of flue gas low temperature corrosion, which can measure the corrosion condition of different materials by different flue gas compositions and temperature corrosion speeds. Besides, effects of low temperature corrosion factors are analyzed to find the best exhaust gas temperature and the surface material of tail heating surface.

Failure analysis of corrosion cracking and simulated testing for a fluid catalytic cracking unit

The failure of a fluid catalysis and cracking unit (FCCU) in a Chinese refinery was investigated by using nondestructive detection methods, fracture surface examination, hardness measurement, chemical composition and corrosion products analysis. The results showed that the failure was caused by the dew point nitrate stress corrosion cracking. For a long operation period, the wall temperature of the regenerator in the FCCU was below the fume dew point. As a result, an acid fume NOx-SOx-H2O medium present- ed on the surface, resulting in stress corrosion cracking of the component with high residual stress. In order to confirm the relative conclusion, simulated testing was conducted in laboratory, and the results showed similar cracking characteristics. Finally, some sug- gestions have been made to prevent the stress corrosion cracking of an FCCU from re-occurring in the future.

A successful case of hydrocarbon dew point analysis during mixing of natural gases in transmission pipeline

The occurrence of liquid condensation in natural gas accounts for new challenges during the interoperability between transmission networks,where condensation would lead to higher pressure drops,lower line capacity and may cause safety problem.A successful case of hydrocarbon dew point(HCDP)analysis is demonstrated during the mixing of natural gases in the transmission pipeline.Methods used to predict the HCDP are combined with equations of state(EOS)and characterization of C6+heavy components.Predictions are compared with measured HCDP with different concentrations of mixed gases at a wide range of pressure and temperature scopes.Software named"PipeGasAnalysis"is developed and helps to systematic analyze the condensation problem,which will provide the guidance for the design and operation of the network.

Research on the Arrangement of Dew Point Temperature Detectors of Capillary Plane Radiation Air-Conditioning

Based on analysis of the reason and process of condensation on ceiling radiant cooling panels, two kinds of arrangement of detectors are put forward. The physical model is established, the results show that detectors are arranged as the form of triangle is more suitable. It can not only satisfy the use requirement but also it is economical and practical. Finally we can conclude that the inlet water temperature 0.5°C higher than dew point temperature is safe and reliable.

Melting and Corrosion Behavior of Al-9Zn Based Alloys with Cu and Mg Additions

In the present paper, the effect of Mg and Cu additions on melting, mechanical and corrosion behavior of Al-9Zn alloy was studied and analyzed. It was found that, addition of Cu and Mg led to form the Al-Cu, Al-Mg and Mg-Zn intermetallic compounds. These compounds tend to increase the hardness values due to the precipitation strengthening hardening mechanism of these compounds. Also corrosion behavior of the Cu and Mg content alloys measured by the weight loss method is better than those of the Al-9Zn alloy. Furthermore, corrosion resistance of the Cu content alloys is superior to that of the Mg content alloys.

Analysis and Test on Influence Factors of Dew Drop Condensation in Dew Point Hygrometer

The condensation process of dew droplets is influenced by many factors. Adew point condensation image observation system was built to improve the responsespeed of dew point detector under different measuring conditions. The basic mechanismof dew drop condensation growth was studied and the influence of various factors on thedew drop growth rate were analyzed. And the accuracy of the influence results wasverified based on the improved Hough transform circle detection. The results show thatthe growth rate of dew droplets is affected by ambient temperature, dew pointtemperature, mirror temperature and air velocity. The observed variation of the averageradius of dew droplets is consistent with the theoretical calculations. The maximumradius error is less than 4 μm, the initial error is larger, and the error oscillates in themiddle and late stages of condensation. The establishment of condensation mechanism ishelpful to solve the problem in fast determination of dew point temperature under thecold start of dew point meter, and to improve the response speed.

松辽盆地白垩系青山口组一段页岩生、排烃组分特征及页岩油相态演化

松辽盆地白垩系青山口组一段(青一段)页岩有机质热演化程度跨度大、烃类流动性差异强。页岩油相态分析预测是页岩油勘探开发的重要难题。用低成熟页岩样品开展封闭体系及半封闭体系有机质热解实验,根据生、排烃组分特征对滞留烃的轻烃散失进行补偿校正,研究了页岩油组分演化特征。结合中央坳陷区主要生油凹陷典型井埋藏史、热演化史,研究了页岩油相态演化规律,提出了轻质页岩油勘探有利区和开发压力保护条件。研究结果表明:地质条件下随着有机质成熟度的升高,页岩油组分中轻质组分比例不断增加、气体逐渐增多,相包络线从高露点温度、低泡点压力依次向低露点温度、高泡点压力演化。齐家-古龙凹陷青一段页岩油在嫩江组中期油藏向挥发油油藏转化,长岭凹陷青一段页岩油从嫩江组末期开始油藏向挥发油油藏转化,三肇凹陷青一段页岩油则始终为黑油油藏。无论是黑油油藏还是挥发油油藏,均为单一液相。松辽盆地中央坳陷区青一段页岩油挥发油油藏主要分布在齐家-古龙凹陷中心和长岭凹陷北部有机质成熟度(镜质体反射率Ro)为1.3%~1.6%、地层压力为12.2~22.4 MPa的区域。

连续退火炉露点对汽车用高强钢磷化处理特性的影响

对含0.18%C、1.6%Si、2.2%Mn(质量分数)的汽车用高强钢板在露点为-40、-20、-10、-5、0和10℃的炉气氛中进行了830℃保温2 min后氢气冷却的退火,随后对钢板进行了磷化处理。采用辉光放电光谱仪、扫描电子显微镜和表面电位检测等方法研究了退火气氛露点对汽车用高强钢板磷化特性的影响。结果表明:随着退火气氛露点的提高,钢板的磷酸盐膜覆盖率上升,在露点≤-20℃的气氛中退火的钢板磷酸盐膜覆盖率仅为30%,而在露点≥0℃的气氛中退火的钢板磷酸盐膜覆盖率达90%以上;钢板表层形成Si、Mn氧化物是退火气氛露点提高时钢板磷化处理特性改善的重要原因。

俄油常减压装置常压塔顶系统腐蚀泄漏分析

某石化公司100%俄油炼制常减压装置运行仅7个月,常顶换热器出口至常压塔顶空冷入口管线先后发生10处腐蚀泄漏。通过对塔顶系统的腐蚀介质分析、腐蚀流程分析、腐蚀机理分析及工艺防腐分析,从腐蚀介质含量、工艺参数控制、选材等方面,寻找发生腐蚀泄漏的原因,并提出相应的工艺防腐建议,保证装置长周期运行。

常压塔顶回流系统多相腐蚀流的分布规律及露点腐蚀特性预测

针对某炼化企业常压塔顶回流系统,采用AspenPlus软件构建了多组分流体相态-离子平衡模型,获得了塔顶挥发管线内腐蚀性介质HCl、H_(2)S的气液平衡分布情况,实现了塔顶管道内腐蚀流体分布量化特性预测。结果表明:随着温度的降低,水相中组分HCl、H_(2)S的摩尔流量显著增加,通过初始溶解温度确定露点温度为101.2℃,露点处pH最低可达2.59,露点腐蚀发生在塔顶出口管线附近;塔顶出口管道有3个液膜覆盖率较高的区域,分别是挥发管线入口垂直管壁、弯头内壁和水平管下壁,在露点处大部分HCl气体溶解在冷凝水汇聚成的初始液膜中,因此初始液膜汇聚的区域就是腐蚀频发的区域。

地基微波辐射计露点温度廓线估算方案及初步应用

面向业务和台站实际,针对露点温度直接和间接计算经验公式的不确定性,结合地基微波辐射计LV2级数据特征,开展了露点温度估算方案适用性及应用讨论,旨在为预报员提供高时空分辨率的基础物理量露点温度来判识大气饱和程度,服务于强对流天气预报预警分析。研究表明:(1)相对湿度是主导露点温度直接和间接计算公式计算结果差异的敏感因子。地基微波辐射计露点温度估算方案可为相对湿度小于50%时,采用直接计算公式;相对湿度为50%~99%时,采用间接计算公式;相对湿度为100%(饱和)时,温度大于-48.75℃,采用间接计算公式,温度小于-48.75℃,采用直接计算公式。(2)地基微波辐射计估算的露点温度产品精度保持了温度产品的高相关性,较大程度上改善了系统偏差,但离散程度略有扩大。其中,相关系数由0.99变成0.98,降低了0.01;系统性偏差由-3.18℃变成-0.98℃,缩小了2.2℃;均方差由4.92℃变成5.26℃,扩大了0.34℃。(3)相较相对湿度,估算的露点差对高湿区(相对湿度大于70%以上)较为“敏感”,能很好地“勾勒”出云等水凝物内部水汽饱和状态及其特征结构,便于用户判断出饱和区、非饱和区及两者过渡区;与地基微波辐射计直接测量产品联合,可监测强对流天气发生前、中、后水凝物垂直结构特征及其演变,便于天气预报预警,其中预警提前量可达0.5~1.0 h,降水结束预报提前量接近10 min。

硫化氢汽提塔塔顶管线腐蚀及应对措施

硫化氢汽提塔塔顶管线产生腐蚀的主要原因是塔顶管线水平管段在塔顶物料转入水平段时出现流速降低,再加上塔顶注入的缓蚀剂主要落在管线的中下部,使得水平管段中上部腐蚀速率变快,而氯化氢、氯化铵盐结晶吸潮和保温等因素形成的低温则促进了水平管段的腐蚀。通过使用缓蚀剂喷头、注水、良好的保温和操作参数的优化可降低汽提塔顶管线腐蚀速率。

基于PLC控制器的造纸机干燥部管理方案研究

为实现针对造纸机干燥部的自动化管理,节约造纸企业的蒸汽使用量,降低纸张生产成本,基于造纸机干燥部的基本工艺流程对闪蒸罐液位、气罩送风温度和气罩露点温度实施重点监控,并通过S7-300 PLC控制技术对相关环境的车间设备进行自动化控制。在此基础上,通过STEP7软件编辑自动化管理方案运行程序,并采用Win CC组态软件组建终端操作界面。经试验研究发现,所设计的系统终端操作界面友好直观,数据信息交互方便快捷,造纸企业5个月内的平均吨纸汽耗量下降了0.214吨,纸张生产成本进一步降低。

天然气中掺氢对计量物性参数的影响分析

在天然气管道中掺入氢气是进行大规模天然气输送的有效途径,但氢气会对管输水力和热力特性造成影响,进而影响与计量相关的物性参数。基于此,以常规天然气、页岩气及伴生气等三种典型气质组成为基础,系统分析了不同掺氢条件对管输温度、压力的影响及天然气物性参数的变化规律,探讨了天然气掺氢对计量分析的影响。结果表明,掺氢浓度与掺氢天然气温度呈反比,升高温度或降低压力可以减少掺氢天然气的沿程温降;采用GERG-2008方程计算压缩因子的结果准确度明显高于AGA8-92DC方程,随着温度降低、氢气浓度增加,计算结果误差明显增大。建议管道中掺氢浓度不应超过10%;并从改造气相色谱仪、加速标准气体制备、完善量值溯源和标准体系建设等方面入手,逐步实现掺氢天然气计量的标准化和工业化。

海上平台三甘醇脱水装置故障分析及工艺优化

目的解决某海上平台三甘醇脱水装置无法达到脱水要求的问题。方法基于现场实际生产数据,采用HYSYS软件进行该工艺系统的模拟分析,找出该系统运行问题的原因。结果脱水塔入口天然气中水含量过高是影响脱水系统效果的主要因素,改造方案应考虑入口过滤分离器和重沸器改造两方面。结合平台实际情况,最终确定改造方案为更换入口过滤分离器滤芯与重沸器电加热器。改造后,在表压5.2 MPa下的干气水露点从6℃降至-23℃,达到预期效果,且为后续扩容预留了操作空间。结论该海上平台三甘醇脱水装置处理量无法达到设计值的原因可能是入口过滤分离器性能不达标导致脱水塔入口天然气中水含量过高,建议在进行三甘醇脱水装置工艺设计时,严控入口过滤分离器处理指标,并根据入口过滤分离器处理指标配套三甘醇脱水装置。

露点传感器响应时间测试方法研究

论述了当前露点传感器响应时间特性测量在国内大型设备系统测试领域中的作用和意义,介绍了当前国内气体露点温度响应时间测量校准研究现状,设计了一种气体露点温度响应时间测试系统。该系统以测量准确度高、阶跃控制量程范围广、系统操作便捷等优势,为解决气体露点温度响应时间高精度测量的难题提供了技术支持。使用本装置分别对石英谐振露点传感器和氧化铝露点传感器的响应时间特性开展测试工作,研究结果可为未来露点传感器湿敏元件响应时间特性的研究和改进提供参考。