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.

A Theoretical Study on Energy of a Gaseous System Vis-a-Vis Mass and Temperature

To study various properties of a gas has been a subject of rational curiosity in pneumatic sciences. A gaseous system, in general, is studied by using four measurable parameters namely, the pressure, volume, number of moles and temperature. In the present work, an attempt is made to study the variation of energy of an ideal gas with the two measurable parameters, the mass and temperature of the gas. Using the well known ideal gas equation, PV = nRT where symbols have their usual meanings and some simple mathematical operations widely used in physics, chemistry and mathematics in a transparent manner, an equation of state relating the three variables, the energy, mass and temperature of an ideal gas is obtained. It is found that energy of an ideal gas is equal to the product of mass and temperature of the gas. This gives a direct relationship between the energy, mass and temperature of the gas. Out of the three variables, the energy, mass and temperature of an ideal gas, if one of the parameters is held constant, the other two variables can be measured. At a constant temperature, when the power or energy is stabilized, the increase in the mass of the gas may affect the new works and an engine can therefore be prevented from overheating.

Fretting Wear Behavior of Medium Carbon Steel Modified by Low Temperature Gas Multi-component Thermo-chemical Treatment

The introduction of surface engineering is expected to be an effective strategy against fretting damage. A large number of studies show that the low gas multi-component （such as carbon, nitrogen, sulphur and oxygen, etc） thermo-chemical treatment（LTGMTT） can overcome the brittleness of nitriding process, and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly. However, there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now, which limits the applications of fretting. So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50 （0.48%C） steel prepared by low temperature gas multi-component thermo-chemical treatment （LTGMTT） technology. The fretting wear tests of the modified layer flat specimens and its substrate （LZ50 steel） against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2 μm to 40 μm. Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope（SEM）, optical microscope（OM）, X-ray diffraction（XRD） and surface profilometer. The experimental results showed that the modified layer with a total thickness of 60 μm was consisted of three parts, i.e., loose layer, compound layer and diffusion layer. Compared with the substrate, the range of the mixed fretting regime（MFR） of the LTGMTT modified layer diminished, and the slip regime（SR） of the modified layer shifted to the direction of smaller displacement amplitude. The coefficient of friction（COF） of the modified layer was lower than that of the substrate in the initial stage. For the modified layer, the damage in partial slip regime（PSR） was very slight. The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination. The modified layer presented better wear resistance than the substrate in PSR and MFR; however, in SR, the wear resistance of the modified layer decreased with the increase of the displacement amplitudes. The experimental results can provide some experimental bases for promoting industrial application of LTGMTT modified layer in anti-fretting wear.

Preparation of polythiophene/WO_3 organic-inorganic hybrids and their gas sensing properties for NO_2 detection at low temperature

Polythiophene/WO3（PTP/WO3）organic-inorganic hybrids were synthesized by an in situ chemical oxidative polymerization method,and char- acterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）and thermo-gravimetric analysis（TGA）.The Polythiophene/ WO3 hybrids have higher thermal stability than pure polythiophene,which is beneficial to potential application as chemical sensors.Gas sensing measurements demonstrate that the gas sensor based on the Polythiophene/WO3 hybrids has high response and good selectivity for de- tecting NO2 of ppm level at low temperature.Both the operating temperature and PTP contents have an influence on the response of PTP/WO3 hybrids to NO2.The 10 wt%PTP/WO3 hybrid showed the highest response at low operating temperature of 70-C.It is expected that the PTP/WO3 hybrids can be potentially used as gas sensor material for detecting the low concentration of NO2 at low temperature.

Investigations on the Corrosion Behaviour and Structural Characteristics of Low Temperature Nitrided and Carburised Austenitic Stainless Steel

The wear resistance of austenitic stainless steels can be improved by thermo-chemical surface treatment with nitrogen and carbon. However, it is possible that the corrosion resistance will be impaired by the precipitation of chromiumnitrid or -carbide. The present contribution deals with investigations of the corrosion behaviour and structural characteristics of a low temperature nitrided and carburised austenitic stainless steel. The material investigated was AISI 316L (X2CrNiMol7-12-2) austenitic stainless steel. A commercial plasma-nitriding unit (pulsed dc) was used for the nitriding and carburising process. Additional samples were treated by the gasoxinitriding process for a comparison between plasma- and gasoxinitriding. The nitrided and carburised layer of austenitic stainless steel consists of the nitrogen or carbon S-phase (expanded austenite), respectively. X-ray diffraction investigations show the typical shift of the peaks to lower angles, indicating expansion of the fee lattice. Also the X-ray diffraction technique was employed to study the residual stresses in the nitrogen and carbon S-phase. The corrosion behaviour of surface engineered samples was investigated with electrochemical methods. Anodic potentiodynamic polarisation curves were recorded for testing the resistance against general corrosion (in H2SO4) and pitting corrosion (in NaCl).

Gas sensing performance of polyaniline/ZnO organic-inorganic hybrids for detecting VOCs at low temperature

Polyaniline （PANI） was prepared by the chemical oxidative polymerization of aniline, and ZnO, with the mean particle size of 28 nm, was synthesized by a non-aqueous solvent method. The organic-inorganic PANI/ZnO hybrids with different mass fractions of PANI were obtained by mechanically mixing the prepared PANI and ZnO. The gas sensing properties of PANI/ZnO hybrids to different volatile organic compounds （VOCs） including methanol, ethanol and acetone were investigated at a low operating temperature of 90°C. Compared with the pure PANI and ZnO, the PANI/ZnO hybrids presented much higher response to VOCs. Meanwhile, the PANI/ZnO hybrid exhibited a good reversibility and a short response-recovery time, implying its potential application for gas sensors. The sensing mechanism was suggested to be related to the existence of p-n heterojunctions in the PANI/ZnO hybrids.

Effects of Imidapril on Venous Blood Gas Values in Broiler Chickens Exposed to Low Ambient Temperature

ObjectiveThis study was designed to evaluate the effects of imidapril on blood gas parameters in broiler chickens. MethodTwenty-four chickens were randomly divided into three groups (n=8), control group, low temperature group and imidapril group. Chickens in low temperature group and imidapril group were exposed to low ambient temperature (12-18 ℃) from age at 14 d to 45 d, whereas the control group was exposed to 24-30 ℃; chickens in imidapril group were gavaged with imidapril (3 mg/kg) once daily for 30 d. At age of 45 d, blood was taken from wing vein and blood gas parameters were evaluated by blood gas analyzer in Luoyang Central Hospital Affiliated to Zhengzhou University. ResultImidapril significantly increased hematocrit (HCT) and total hemoglobin content (T HBC ) and blood Na concentration in broiler chickens exposed to low ambient temperature. No significant differences were observed in pH, P CO 2 , P O 2 , K + , Ca 2+ , HCO 3-, HCO 3std , T CO 2 , BE and SO 2c . ConclusionImidapril increases hematocrit, total hemoglobin content and blood Na + concentration in chickens exposed to low ambient temperature.

Research on deepwater synthetic drilling fluid and its low temperature rheological properties

With the rapid development of deepwater drilling operations,more and more complex technical challenges have to be faced due to the rigorous conditions encountered.One of these challenges is that the drilling fluid used must had good rheological properties at low temperatures and high ability to inhibit hydrate formation.Synthetic drilling fluid has been widely applied to deepwater drilling operations due to its high penetration rate,excellent rheological properties,good ability to prevent hydrate formation,and high biodegradability.A synthetic drilling fluid formulation was developed in our laboratory.The rheological properties of this drilling fluid at low temperatures （0-20 °C） were tested with a 6-speed viscometer and its ability to inhibit hydrate formation was evaluated at 20 MPa CH 4 gas and 0 °C by differential scanning calorimetry （DSC）.Several factors influencing the low temperature rheological properties of this synthetic drilling fluid were studied in this paper.These included the viscosity of the base fluid,the amount of CEMU and organic clay,and the water volume fraction.

Effect of processing temperatures on characteristics of surface layers of low temperature plasma nitrocarburized AISI 204Cu austenitic stainless steel

The influence of processing temperatures on the surface characteristics of AISI 204Cu austenitic stainless steel was investigated during a low temperature plasma nitrocarburizing.The resultant layer was a dual-layer structure,which comprises a N-enriched layer on the top of C-enriched layer.The surface hardness and the layer thickness increase up to about HV 0.05 1000 and 20μm with increasing temperature.The specimen treated at 400°C shows a much enhanced corrosion resistance compared to the untreated steel.A loss in corrosion resistance was observed for specimens treated at temperatures above 430°C due to the formation of Cr2N.

Atmospheric Corrosion of AZ31B Magnesium Alloy in the Antarctic Low-Temperature Environment

In this work,the outdoor corrosion behavior of AZ31B magnesium alloy in the Antarctic atmospheric environment was investigated.The surface corrosion state of the specimens exposed to the Antarctic atmosphere for 1 month and 24 months differ significantly.The corrosion rate after 1 month during the summer season was 19.82 g/m^(2)·year and it decreased to 13.87 g/m^(2)·year after two years’exposure.Corrosion is initiated with pitting corrosion and then evolved to uniform corrosion with prolonging exposure time.The skyward surface exhibited a much severe corrosion than that of the groundward surface,attributed to the long-term existence of the adsorbed electrolyte layer.The corrosion products formed on the alloy exposed in Antarctica environment were MgCO_(3)·3H_(2)O,MgCO_(3)·5H_(2)O and Mg_(2)CO_(3)(OH)_(2)·0.5H_(2)O,with the MgCO_(3)·3H_(2)O as the dominant phase in the initial stage and the Mg_(2)CO_(3)(OH)_(2)·0.5H_(2)O as the dominant phase after long-term exposure.

80-3Cr油管钢在CO_(2)驱环境下的性能研究与应用

针对CO_(2)驱高CO_(2)分压、高H_(2)S分压、低温井筒环境造成N80、P110管柱失效的问题,开展了80-3Cr、N80、P110三种管材的耐CO_(2)腐蚀、抗H_(2)S应力腐蚀开裂、耐低温冷脆对比评价试验。结果表明,不同CO_(2)工况条件下,N80、P110、80-3Cr油管在添加缓蚀剂情况下的腐蚀速率分别为0.0549 mm/a、0.0645 mm/a、0.0333 mm/a;80-3Cr油管的腐蚀速率明显低于N80、P110油管;80-3Cr油管在不同H_(2)S环境下均未出现应力腐蚀开裂,具有较好的抗H_(2)S应力腐蚀性能;在-20℃的低温环境下,N80和P110油管冲击功分别只有80-3Cr油管的62.6%和23.2%;80-3Cr油管在CO_(2)驱油现场应用后,管柱失效率从2019年的20%下降到0,取得显著效果。

某700 MW锅炉水冷壁高温腐蚀原因分析及其防治措施

针对某电厂700 MW对冲式燃烧锅炉水冷壁腐蚀严重问题,对该锅炉高温腐蚀产生的原因进行了分析。在现场割取了腐蚀的水冷壁管,对其腐蚀垢层进行了X射线衍射(XRD)、能量色散X射线谱(EDS)和扫描电镜(SEM)分析,结果发现腐蚀产物中主要含有ZnS、FeS、Fe_(7)S_(8)、Fe_(3)O_(4)和α-FeOOH,推定此炉主要为硫化物型高温腐蚀,并制定了该锅炉的防治措施。

极地低温冻融循环环境下高强钢的腐蚀行为研究

目的深入研究极地大气对高强钢腐蚀的影响,探清腐蚀机制。方法开展室内模拟试验,采用质量损失测试、电化学测试以及腐蚀产物分析等方法,研究Ni-Cr-Mo-V高强钢在极地大气‒45~5℃低温冻融循环环境中的腐蚀机理。结果随着试验周期的延长,高强钢的腐蚀不同程度加深。2个月后,已形成相对较厚的锈层,内部有大量松散的腐蚀产物。在试验3个月后,发现金属表面已经被腐蚀产物覆盖,且表面的腐蚀层产生裂纹。交流阻抗测试和动电位极化测试结果表明,高强钢的容抗弧半径和自腐蚀电位变化较大,耐腐蚀能力较弱。通过XRD和拉曼光谱对腐蚀成分进行表征发现,在低温冻融循环环境中,高强钢腐蚀产物主要为α-FeOOH、β-FeOOH、γ-FeOOH和Fe_(3)O_(4)/γ-Fe_(2)O_(3)。结论随着低温冻融循环时间增长,高强钢的耐蚀性持续退化。

耐高温可加重酸性交联压裂液的研发与性能评价

针对高温深层油气藏埋藏深,地层破裂压力高、压裂施工难度大的问题,开展耐高温可加重压裂液研究。通过室内实验自主合成了一种耐温抗盐的聚合物稠化剂TS-700和适用于酸性交联的有机锆交联剂OZ-60,优化了添加剂加量,形成了一种耐温180℃可加重酸性交联压裂液体系。研究了加重压裂液黏度、减阻、延迟交联规律,并评价了耐温抗剪切性能、悬砂性能、破胶及岩心伤害性能和管柱腐蚀能力。结果表明,该体系在酸性条件下进行交联,通过调整交联剂加量和pH,交联时间可控在3~12 min;高温有利于黏度提升,加重降低了基液黏度,密度为1.20 g/cm^(3)的加重压裂液配方在180℃条件下剪切120 min后,保留黏度仍大于70 mPa·s。加重剂会在一定程度上降低压裂液的减阻性能,但在不同稠化剂加量下的加重压裂液减阻率仍可达68.04%以上,满足有效降低长距离井筒中摩阻损失的要求。交联压裂液在常温和100℃条件下均展现出优异的悬砂效果,支撑剂沉降速率低。破胶与岩心伤害实验结果表明,交联体系在0.03%破胶剂加量下即可实现完全破胶,破胶液对致密岩心伤害率仅为19.42%。高温高压动态腐蚀实验结果表明,全配方压裂液对N80和13Cr钢材具有较低的腐蚀速率,能够保障现场压裂管柱的安全性。

水分对混合动力汽车发动机油性能的影响

利用机械搅拌机将蒸馏水均匀分散在发动机油中,形成“油包水”结构的稳定乳化液,利用石油产品低温泵送黏度测定法、铜片腐蚀测定法、润滑油氧化诱导期测定法、倾点测定法、四球法分别评价水分对混合动力汽车发动机油理化性能的影响。试验结果表明:水分对油品的低温泵送黏度、氧化诱导期、最大无卡咬负荷、烧结负荷及磨斑直径等性能有影响,随着水含量的增加,其油品的低温流动性、抗氧化性、承载能力及抗磨损性能变差;对油品的倾点、腐蚀性能基本无影响。(图0表5参考文献5)

一氧化碳变换冷凝液系统异常现象及对策

介绍了一氧化碳变换冷凝液系统工艺,针对高、低温冷凝液系统在运行过程中出现的冷凝液闪蒸槽压力低、高温冷凝液泵温度高、低温冷凝液汽提塔液泛、压力点及汽提气分离器液位计管道结晶堵塞和变换冷凝液系统腐蚀等问题进行了原因分析,通过在冷凝液闪蒸槽增加氮气管线、增加高温冷凝液泵机封水换热器、减少洗氨塔锅炉给水量、增加伴热管线和直喷蒸汽、使用加厚耐腐蚀管道等措施解决了上述问题,实现了一氧化碳变换冷凝液系统的长周期稳定运行。

空间电场对冷鲜猪肉低温保鲜效果的影响

为探究空间电场技术对冷鲜猪肉低温保鲜贮藏过程中品质的影响,通过对冷鲜猪肉鲜度指标、低场核磁共振弛豫图谱及成像的分析,探究不同电场强度(0、3、6、9 kV/m)下冷鲜猪肉低温(4℃)保鲜品质的变化。结果表明,与对照组相比,试验组的冷鲜猪肉品质明显改善,猪肉肌纤维排列更紧密,且添加9 kV/m电场强度的猪肉样品品质最优,在贮藏末期,其总挥发性盐基氮(total volatile basic nitrogen,TVB-N)值和汁液流失率仅为14.82 mg/100 g和4.22%,水分含量高达71.33%,而对照组下降至66.34%。通过低场核磁共振技术对弛豫时间T_(2)和磁共振成像(magnetic resonance imaging,MRI)进行分析,T_(21)、T_(22)和T_(23)的峰面积均出现降低,说明3种形式的水出现迁移的现象,但试验组的横向弛豫时间T_(21)、T_(22)、T_(23)均大于对照组,且9 kV/m的电场强度抑制水分转化和减少的效果最佳。在MRI成像分析中,对照组成像为黄绿色,水分流失严重,电场组成像为红色,且施加9 kV/m电场强度的猪肉样品保水性最好。综上所述,空间电场能够抑制冷鲜猪肉的品质劣变,对冷鲜猪肉具有良好的保鲜效果。

95+技术在加热炉中的应用及节能减排效果分析

对某炼化企业加热炉采用高效超净余热回收(95+)技术的方案路线和实际应用效果进行了介绍。该技术核心在于燃料气精制系统和燃料气、空气双并联换热系统,以及两段式空气预热器布置。在多套装置中的应用结果表明,95+技术可满足设计指标要求,并且具有可观的经济效益和社会效益,为今后同类型装置或其他加热炉节能减排提供借鉴和参考。

低温熔融盐体系电沉积制备铝锡合金

以AlCl_(3)-NaCl-KCl低温熔融盐体系作为电解质,无水SnCl_(2)作为原料,对电沉积制备Al-Sn合金进行研究。通过扫描电子显微镜(SEM)、能谱(EDS)和X射线衍射仪(XRD)分析合金产物的形貌和成分组成;通过极化曲线法和摩擦磨损实验对合金产物的耐蚀性和耐磨减摩性进行检测分析;通过维氏硬度计和涂层附着力自动划痕仪对合金产物的硬度与膜基结合力进行表征。结果表明:当SnCl_(2)添加量为0.04~0.08 g时可制备出锡含量为10%~18%的中锡铝合金,最佳沉积温度为160~200℃、沉积时间为40~50 min、电流密度为40~50 mA/cm^(2);随镀层中锡含量的提高,其耐蚀性逐渐变差,而耐摩擦磨损性能先提高后降低,并在SnCl_(2)添加量为0.06 g,即镀层中锡的含量为14 wt%时有最佳摩擦磨损性能;沉积温度对合金镀层的硬度及结合力有很大影响,随沉积温度的升高,合金镀层的膜基结合力和硬度均呈现先提高后降低的趋势,当沉积温度为200℃时,其结合力和硬度最佳。

降低高温缓蚀剂磷含量效果研究

某石化常减压装置加工能力为6.0 Mt/a,主要加工低硫重质中间基原油,所产直馏蜡油作为蜡油加氢装置原料。现阶段该装置高温部位防腐手段:减一中、减二中、洗涤段内回流等处注入一定量的高磷高温缓蚀剂(磷含量约为2%),取得了较好的工艺防腐效果。近期在生产中发现蜡油加氢装置原料过滤器反冲洗频繁且换热器、反应器存在压降升高较快、结垢严重等问题,对结垢物质进行采样分析发现其中含有磷化物,现怀疑可能与常减压装置向油品中注入高含磷药剂有关。为此开展“低磷高温缓蚀剂应用”的专项活动课题,以期在使用低磷高温缓蚀剂的前提下,保证常减压装置高温防腐效果并使下游装置生产问题得到改善。