锅炉的腐蚀与结垢(连载)

三、防止锅炉水腐蚀的方法防止锅炉水腐蚀的方法有:①进行水处理(软化、脱氧、加入添加剂等);②加强锅炉的管理。如:投产前进行清洗、钝化,运行时合理操作,停炉时很好保护。因此,防止锅炉水腐蚀应采取全面腐蚀控制方法。下面简单介绍除氧、除二氧化碳、防止碱脆几种方法。水质处理已成为一门专门技术,故不予介绍了。 1.脱氧:氧是中性水溶液中腐蚀的一个去极化剂,因此为了减少锅炉的腐蚀,应该脱去     

用需氧菌来减缓钢筋腐蚀？

<正>日本爱媛大学(Ehime University)研究人员最近发表了一项研究成果,认为将某种需氧菌加入混凝土,可以使混凝土中的钢筋的腐蚀情况得到缓解,即需氧菌能够减缓腐蚀。为了降低引起腐蚀的氧含量,研究人员在水泥混凝土中加入了枯草芽孢杆菌,这种需氧菌具有对不利于其生存环境(如多盐分环境等)的抵御本能,当需氧菌所需养分缺乏时,产生一种孢子内壁,并力图改善其生存环境,并从中存活和繁殖。     

防止热力设备氧腐蚀技术

介绍热力设备在运行及停备用期间氧腐蚀的特征、影响氧腐蚀的因素及其氧腐蚀的防止方法。     

氧氯化反应器腐蚀的形成与对策

1 前言金属的腐蚀,一般分为化学腐蚀和电化学腐蚀。而金属在机械因素影响下的应力腐蚀,根据腐蚀机理的不同,在本文中应属电化学腐蚀。有时两类腐蚀又相互作用和影响,从而更加快了腐蚀的速度。如在氧氯化反应器内就同时存在上述两类腐蚀的可能性。     

锅炉的氧腐蚀与解决方法研究

氧腐蚀是锅炉正常运行的大威胁,本文对氧腐蚀的原理、危害及目前解决锅炉氧腐蚀的办法进行总结和概括,探讨解决氧腐蚀的安全、合适、有效的方法。     

天然气加热炉腐蚀及结垢原因分析

通过对新疆某油田采油厂水套加热炉附着物的分析,发现加热炉炉套(水侧)存在严重的腐蚀现象,并伴有结垢现象存在.经理论分析及实验室验证,造成加热炉炉套(水侧)腐蚀的主要原因为:氧腐蚀、促进腐蚀性离子对氧腐蚀的促进作用、局部腐蚀、铁垢腐蚀、干湿线腐蚀以及碱腐蚀.造成加热炉炉套内结垢的主要原因是:炉水中重碳酸盐受热分解后,与硬度成分结品析出,与加热炉金属腐蚀产物粘合在一起形成结垢.     

锅炉停用时的腐蚀与保护

锅炉在运行中或停用时 ,锅炉中的介质会使锅炉的金属发生腐蚀 ,从而降低其使用寿命 .在锅炉中以氧分子作为去极化剂的腐蚀过程 ,称为氧去极化腐蚀 (即吸氧腐蚀 ) ,是自然界中普遍存在而且破坏性较大的一类腐蚀 .锅炉系统设备停用期间发生的腐蚀是属于氧去极化腐蚀 .停炉时氧的浓度大 ,使锅炉水、汽侧金属表面产生强烈腐蚀 ,其危害性要比运行时严重 .主要原因为 :其一 ,锅炉停用后 ,水汽系统内部的压力、温度逐渐下降 ,蒸汽凝结 ,外界空气就会从设备密封不严密处大量进入水汽系统 ,使系统内部有氧气 .其二 ,金属表面潮湿 ,在其上形成水膜 ,或…     

膨胀机主轴缝隙腐蚀的电化学分析

为探究膨胀机主轴的缝隙腐蚀行为,搭建了模拟缝隙腐蚀实验装置。通过电化学测试,确定了不同缝隙位置处的自腐蚀电位随时间的变化规律,并揭示了缝隙内腐蚀反应的发展过程。结果表明:缝隙内腐蚀反应经历双电层形成-氧浓差电池形成-金属水解三个反应过程。在富氧条件下,腐蚀产物的主要成分为Fe(OH)2。随着氧气的耗尽,氧浓差电池形成,腐蚀产物逐渐向FeOOH和Fe3O4转变。     

电阻腐蚀探针在冷却水腐蚀监测中的应用

一、前言电阻腐蚀探针是快速、灵敏、方便并可连续测量腐蚀的工具,六十年代在我国炼油系统已获得广泛应用。目前测定仪已从便携式人工测量发展到自动记录,可作为在线监控用。探针结构也在不断改进,有可供实验室和生产现场使用的各种形式电阻腐蚀探针利用腐蚀中金属试件电阻变化来测定腐蚀。与电化学快速腐蚀测定法原理不同。本方法对测定非电解质腐蚀(如油品     

水流速度对腐蚀的影响

碳钢在冷却水中被腐蚀的主要原因是氧的去极化作用,而决定腐蚀速度的又与氧的扩散速度有关。流速的增加将使金属壁和介质接触面的层流层变薄而有利于溶解氧扩散到金属表面。同时流速较大时,可冲去沉积在金属表面的腐蚀、结垢等生成物,使溶解氧更易向金属表面扩散,导致腐蚀加速,所以碳钢的腐蚀速度是随着水流速度的升高而加大。随着流速进一步的升高,腐蚀速度会降低,这是因为流速过大,向金属表面提供氧量已达到足使金属表面形成氧化膜,起到缓蚀的作用。如果水流速度继续增加,则会破坏氧化膜,使腐蚀速度再次增大。当流速很高时(>20 m/s),腐蚀类型将转变     

Molecular dynamics simulation of oxygen diffusion in dry and water-containing poly(vinyl alcohol)

The kinetics and mechanisms of diffusion of oxygen and water in dry and water-containing amorphous syndiotactic poly(vinyl alcohol) were studied at 502 K and normal pressure by molecular dynamics simulation. Penetrant molecule trajectories were obtained in a system with 600 repeating units of poly(vinyl alcohol) and 0, 40 (2.6 wt%) and 80 (5.2 wt%) water molecules. Under dry conditions, oxygen molecules jumped in a cage-like fashion. The oxygen molecule diffused in a liquid-like fashion while water diffusion was cage-like in the system with 5.2 wt% water. The hydrogen bond lifetimes among the water molecules were significantly shorter than those formed between water and the polymer and between different polymer segments. The hydrogen bond lifetimes among all species were, within experimental error, unaffected by the content of water, even though the oxygen diffusivity increased exponentially and the water diffusivity increased to some extent with increasing water content. It seemed that the diffusivity was sensitive primarily to the decrease in concentration of polymer-polymer hydrogen bonds, which followed from the increase in water content. This finding was consonant with the analysis of the oxygen molecule motion relative to the nearest polymer backbone, which revealed that it jumped preferentially along the polymer chain and towards the backbone. This behavior was more pronounced when the dynamics were analyzed over longer distances (5 Å) and it was less pronounced in the water-rich systems. The simulations indicated that water clustering was absent and consequently that water was homogeneously distributed in the polymer systems.     

Water vapor resistance of plasma-polymerized coatings on potassium bromide windows

Plasma-polyme rized (PP) coatings of chlorotrifluoroethylene (CTFE), tetraluoroethylene (TFE), and ethylene were deposited in a capacitively-coupled 13.56-MHz radio-frequency glow discharge on potassium bromide (KBr) infrared windows for moisture protection. The PPTFE coatings deposited slightly downstream of the internal plasma reactor electrodes provided the best moisture protection for the KBr windows. The PPTFE-coated windows tolerated an upper limit relative humidity of about 80 percent at 297°K without visible damage occurring to either window or coating within 24 h (86.4 ks). It appeared from environmental tests that some of the coatings failed to protect the KBr windows from moisture because of defects in the coatings (pinholes, cracks); others failed because of their high water permeability. Elemental analysis of the bulk and photoelectron spectroscopy (ESCA) of the surface of PPTFE coatings deposited downstream of the electrodes revealed that these samples contained less oxygen (from the atmosphere) than coatings deposited between the electrodes. The lower oxygen content of the coatings deposited downstream may have accounted for the improved moisture resistance of these coatings. The PPTFE coatings were posttreated by heating and by cross-linking with activated species of inert gases (CASING). Neither post-treatment technique was effective in improving the moisture resistance of the PPTFE coatings.     

解吸除氧在热水锅炉上的应用

由于缺少适用于热水锅炉的除氧设备及人为因素 ,热水锅炉存在程度不同的溶解氧腐蚀。就热水锅炉氧腐蚀的原因、机理及解吸除氧在热水锅炉上的应用作了分析。介绍了常用除氧设备及方法 ,结合实际使用 ,选用JXCY10 -Ⅰ型解吸除氧器后 ,除氧效果显著     

Investigation to develop methods for removal of oxygen from coals

Several inorganic reducing agents of various chemical characteristics have been tested to see if they reduce the oxygen contained in coal. It was found that oxygen content of coals decreased when they were heated in only water (blank runs). The treatment with the reducing agents containing sulphur did not increase the oxygen removal over that achieved in the blank runs. However, it appears that the ferrous salt catalytically deoxygenated both the lignite and bituminous coals.     

Effect of slag basicity on Turing pattern corrosion of alumina refractory ceramics in the presence of free radicals

Turing pattern corrosion causes serious damage to alumina ceramics. Therefore, the quaternary slag corrosion of alumina refractory ceramics was studied with different slag basicity by adjusting relative content of MgO and Al₂O₃. The results show that reactive oxygen species (ROS) like singlet oxygen and superoxide radicals are generated in the slags. The height of corrosion peak is determined by both the original superoxide radical and the amount of non-bridging oxygen (NBO) of the slags under the change of basicity. Moreover the influence of free radicals on the corrosion peak is greater than that of NBOs. A free-radical reaction was proposed as the formation mechanism of the Turing pattern corrosion peaks based on ROS.     

改进苯甲醛水分分析方法

测定苯甲醛水分含量一直采用甲苯蒸馏法。此方法费时、费力,很不利于节能减排。论述了采用库仑微量水分滴定仪法,该方法分析速度快、准确度高,更适合测量微量水分,同时污染小、不危害职工身体健康、能耗物耗低。     

Storage of cereal bars with mesquite cotyledon (Prosopis chilensis (Mol) Stuntz)

The use of walnut or peanut in the elaboration of cereal bars represents a possible risk of undesirable changes during their storage due to their high content of unsaturated fatty acids in the oil; oxidizing of the fatty acids is one of the main causes of deterioration. Development of new snack products implies the use of packages that should protect the food against the damage caused by light and reduce the oxygen concentration of in their interior. The objective of this investigation was to evaluate the physical, chemical and sensory changes in the storage of cereal bars with peanut or walnut and mezquite cotyledon subjected to two thermal treatments, packed in cellophane or milky polypropilene. Four types of bars were elaborated with 6% of mezquite cotyledon, treated by microwaves or toasted, and with 18% of peanut or walnut. The bars were stored for 90 days at room temperature; and each 30 days it was measured moisture content, peroxides index, water activity, sensory quality and acceptability. The peroxides values (4.9-13.8 meq/kg of oil) indicates that the shelf life of the bars in all the studied treatments was 90 days. The packaging materials used allows to maintain in good conditions, for 3 months, the cereals bars of moisture (7.4-11.2%), water activity (0.50-0.65) and sensory acceptability.     

Experimental and theoretical study of membrane-aerated biofilm reactor behavior under different modes of oxygen supply for the treatment of synthetic wastewater

This study compares, experimentally and theoretically, five different modes of supplying oxygen to a membrane-aerated biofilm reactor (MABR), and search for the more efficient ways of treating wastewaters. A single-tube MABR was used to measure the decrease of an organic substrate (sodium acetate) in water by supplying oxygen in different modes, namely: (1) by feeding the membrane tube either with oxygen or air (or none of them); (2) in some cases by simultaneous sparging air to the residual water. The dynamics of the substrate and oxygen consumption were measured during the batch experiment, and two mathematical models are developed to predict their transient responses using a Monod kinetic with dual substrate limitation. The models predict biomass growth and the production of extracellular polymer substances (EPS), which in turn causes the biofilm to grow; they account for the counter-diffusion of substrate and oxygen within the EPS structure that contains the cells, and one of them incorporates the mass transport by convection and diffusion in the surrounding liquid contained inside the interconnected pores and channels within the biofilm. Transport and kinetic parameters are estimated from experiments, and both models successfully predict concentration measurements in some of the set of experiments. It was found that all of the modes of oxygen supplied in a MABR were more efficient than the traditional suspended cell process.     

草莓（Fragaria × ananassa）叶水提物对UVB致 皮肤损伤的保护作用

在草莓叶水提物（Strawberry leaf water extract，SLWE）制备基础上，测定SLWE成分，抗氧化活性、抑制非酶糖基化（NEG）能力，及SLWE对正常生长人皮肤成纤维细胞（HFF-1）细胞活率、透明质酸（HA）、人I型胶原蛋白（COL I）、羟脯氨酸（HYP）、基质金属蛋白酶1（MMP-1）、基质金属蛋白酶9（MMP-9）含量，评价SLWE延缓皮肤衰老功效。在中波紫外线（UVB）致HFF-1损伤模型基础上，测定SLWE对保护组活性氧（ROS）、丙二醛（MDA）、MMP-1和超氧化物歧化酶（SOD）的影响，探讨SLWE对UVB致HFF-1损伤保护机制。结果表明：SLWE富含Vc、槲皮素、绿原酸、没食子酸及儿茶素类物质，其中槲皮素含量12.86 mg/L，表儿茶素含量10.13 mg/L。SLWE自由基清除能力良好，清除不同自由基能力依次为O2-?＞DPPH＞ABTS＞亚铁离子螯和＞?OH；水溶液体积分数为1%的SLWE非酶糖基化抑制率为87.17%；体积分数大于3%的SLWE可提高HFF-1中HA、COL I和HYP含量（p＜0.05），体积分数为6%的SLWE可降低MMP-1含量（p＜0.01），说明SLWE具有提升皮肤含水量，增加胶原含量，抑制胶原降解，实现延缓衰老的功效；在SLWE对UVB致HFF-1损伤保护模型中，SLWE可有效降低因UVB刺激而产生的ROS，体积分数6%的SLWE可显著降MDA，抑制MMP-1表达，提高SOD活力，说明SLWE有助于缓解氧化应激造成的细胞损伤。     

陶瓷泥料水分电容传感器电路分析

泥料水分快速测定仪中使用的电容传感器主要根据水的介电常数很大，物料本身的介电常数很小这一特点，当物料的含水率发生变化时会引起传感电容的变化。产生这种变化的真正的原因不是料或水的介电常数发生了变化．而是因为物料中的水和料部分的体积百分比发生了变化，探头中水和料形成的电容可分别表示为Cs＝f（B）和CL＝f（1－B），B为水分的体积百分比。传感电容实际上由Cx＝Cs＋CL共同组成，但进一步分析可以发现，泥料的传感电容是由一个固定不变的电容CLo（由料的介电常数所决定）和一个随物料中水分体积百分比B而变化的电容CY并联组成，即Cx＝CY＋CLo,而CY＝0．0884B因此泥料的体积百分比B与传感电容CY呈线性关系，可用数学模型B＝bCY＝bCX＋bCLo来表示。