ODCB精馏塔再沸器气蚀原因分析与改进

针对塔釜再沸器换热效果差、换热管易腐蚀穿孔的问题进行系统分析,得出再沸器出口管线上限流孔板设计不合理是问题的主要原因,针对该问题对限流孔板进行重新设计并采取了一些措施,改进后装置运行状况良好。     

加压塔再沸器换热管泄漏原因分析及改进

针对某厂加压塔再沸器在使用中发生换热管泄漏的问题,结合工艺条件、介质特性与设备结构,通过对换热管振动、介质腐蚀特性和实际操作工艺参数的分析找到加压塔再沸器换热管泄漏的原因,提出改进方案。     

Bfe30-1-1/16MnR管壳式换热器 换热管与管板接头的焊接工艺

本文以氯仿塔再沸器为例,介绍了以白铜板Bfe30-1-1与16MnR金属复合板为管板的管壳式换热器的材料特性,管板加工,特别是换热管与管板连接接头的焊接工艺。     

溶剂再生塔内再沸器的失效分析及改进措施

某芳烃抽提装置溶剂再生塔在运行过程中产生了明显振动,塔内再沸器换热管多次发生泄漏而最终失效,再沸器支撑梁的连接件损坏并断裂,严重影响装置正常运行.通过对再沸器失效原因进行分析,确定了再沸器失效的主要原因并制定了改进措施.     

合成氨气体再沸器的防腐保护措施

一、概述我厂合成氨装置(Ⅰ)脱碳工段的气体再沸器,利用低变气的余热,向二氧化碳再生塔提供再生热源。其安装示意流程如图1所示。气体再沸器是一台立式固定管板热交换器,其技术特性如表1所示。     

羟胺肟化装置汽提塔再沸器泄漏原因分析及改进措施

针对羟胺肟化装置的汽提塔再沸器频繁出现换热管泄漏的情况,分析了再沸器换热管的腐蚀现象、金相显微组织、设备运行操作、进料组分和安装高度等,提出了改进方法并进行实施。结果表明:汽提塔再沸器换热管内壁有明显的点蚀、坑蚀及穿孔情况,被腐蚀穿孔部位主要集中区域在气液分界处;腐蚀处附近未发现夹杂物等明显冶金组织缺陷;设备运行操作正常;进料组分中不存在氯离子腐蚀;塔内控制液位低于再沸器上管板的高度。提出的相应措施为:将再沸器安装高度整体下移400 mm,确保汽提塔液位精准控制在40%;将再沸器的换热器分成上下两部分结构,有利于维修时拆装方便;换热管材质依然选择304L不锈钢。经过改进后的再沸器自2018年10月投入使用以来其运行稳定,未发生列管泄漏事故。     

塔与再沸器的配管及应力分析

再沸器是安装在蒸馏塔底部用来汽化塔底产物的换热器,通常与塔直接连接。塔与再沸器的材质、温度不同,会在竖直方向和管线轴向产生较大的热应力。笔者以甲醇装置为例,运用CAESARII软件,分析了再沸器与甲醇精馏塔连接的情况下产生的热应力;针对再沸器常用的2种支撑方式,提出了消除热应力的设备管口设计方案。     

连接方式对换热器管子—管板接头可靠性影响

介绍了设备的工况、材料和制造工艺.分析了干燥再沸器、卧式再沸器管子-管板接头的失效 原因。对换热管管端外表面进行严格清理并采取液压胀管工艺,有效保证了换热器管子-管板接头的 制造质量。     

双塔精馏主塔再沸器泄露原因分析

介绍了神华包头煤化工公司DAVY双塔精馏运行期间主塔再沸器的运行情况,通过对双塔精馏主塔再沸器在生产运行中的实际情况进行分析,综合各因素来分析说明主塔再沸器泄露的原因,并针对泄露发生的原因提出了相应建议改进措施。     

TDI精馏塔再沸器故障分析及改进

介绍了TDI精馏塔再沸器的换热管易出现腐蚀速率较快、换热管泄露的问题,通过对换热器管程出口压力的测量及对再沸器、限流孔板进行现场拆解观察分析,确定了导致再沸器换热管腐蚀速率较快的主要原因为TDI精馏塔入口处的限流孔板设计不合理,并针对这一主要因素进行了改造,从而使问题从根本上得到了解决。     

佛山市顺德新城区降水中污染物的监测和分析

为掌握佛山市顺德新城区降水中污染物的情况,2015年7月至8月,文章作者分别在雨天进行了降水取样,对降水中的pH、电导率、常见阴离子(F-、Cl~-、NO_3~(2-)、SO_4~(2-))及部分重金属(铅和镉)进行监测分析。选择有相关数据的珠江三角洲和石家庄、厦门等地的降水中污染物的情况进行对比。结果表明,顺德新城区降水中的p H和部分阴离子浓度优于珠江三角洲平均值,酸雨类型属于硫酸和硝酸混合型;其水体洁净程度略差于石家庄;铅和镉的浓度也高于厦门,甚至部分超出了人体能直接接触的安全范围。     

Metabolism of trideuterated iso-lignoceric acid in rats in Vivo and in human fibroblasts in culture

Saturated very long chain fatty acids (fatty acids with greater than 22 carbon atoms; VLCFA) accumulate in peroxisomal disorders, but there is little information on their turnover in patients. To determine the suitability of using stable isotope-labeled VLCFA in patients with these disorders, the metabolism of 22-methyl[23,23,23-²H₃]tricosanoic (iso-lignoceric) acid was studied in rats in vivo and in human skin fibroblasts in culture. The deuterated iso-VLCFA was degraded to the corresponding 16- and 18-carbon iso-fatty acids by rats in vivo and by normal human skin fibroblasts in culture, but there was little or no degradation in peroxisome-deficient (Zellweger’s syndrome) fibroblasts, indicating that its oxidation was peroxisomal. Neither the 14-, 20-, and 22-carbon iso-fatty acids nor the corresponding odd-chain metabolites could be detected. In the rat, the organ containing most of the iso-lignoceric acid, and its breakdown products, was the liver, whereas negligible amounts were detected in the brain, suggesting that little of the fatty acid crossed the blood-brain barrier. Our data indicate that VLCFA labeled with deuterium at the ω-position of the carbon chain are suitable derivatives for the in vivo investigation of patients with defects in peroxisomal β-oxidation because they are metabolized by the same pathways as the corresponding n-VLCFA. Moreover, as iso-VLCFA and their β-oxidation products are readily separated from the corresponding n-fatty acids by normal chromatographic procedures, the turnover of VLCFA can be more precisely measured. A preliminary report of part of this work (Reference 18) was presented at the 5th International Symposium on the Synthesis and Applications of Isotopes and Isotopically Labelled Compounds, Strasbourg, France, June 20–24, 1994.     

高效液相色谱法分析化妆品中微量成分的研究进展

综述了高效液相色谱法在化妆品中防腐剂、防晒剂中紫外线吸收剂以及性激素的检测等几个方面的应用;同时,介绍了分析所用的色谱柱、流动相、使用的检测手段以及样品的提取方法;最后针对目前存在的问题,提出了高效液相色谱用于化妆品中微量成分分析的研究方向和发展前景。     

Denitrification in shallow groundwater in a coastal agricultural area in Japan

In a coastal agricultural area in the central part of Japan (Shizuoka), we found decreasing nitrate concentration with depth in a shallow groundwater, where the depth to water table varied between 0.6 and 1.2 m below ground surface. High nitrate concentrations (5–29 mg N L^–1) were often observed in the upper layer (0–2 m) of the groundwater, but the concentration decreased to less than 1 mg N L^–1 in the deeper layer. Ammonium was scarcely detected, and the concentration of dissolved oxygen was usually low (< 1 mgO₂ L^–1) in the groundwater. Nitrate in the groundwater often had very heavy nitrogen stable isotope ratios (>20{}). There was a negative relationship between nitrogen stable isotope ratio of nitrate and its concentration. When nitrate was injected into the groundwater with acetylene and bromide (a conservative tracer), nitrate concentration decreased to 20% of the initial level within 5 days, accompanied by the increase in nitrite and nitrous oxide concentration and a little change in bromide concentration. These results indicate that microbial denitrification plays a potential role in the decrease of nitrate in shallow groundwater at the study site.     

我国硝酸工业生产技术新进展

系统叙述了我国硝酸工业2000-2007年生产现状及主要技术成果,尤其指出了国产"四合一"机组的成功投运,使我国硝酸国产化装置取得较大的进步,表现在吨酸的铂耗、氨耗和能耗等方面接近国外引进装置水平,同时介绍了国外双加压法硝酸生产技术的进展.我国已成为硝酸生产大国,仍需以先进的技术改造和发展我国硝酸工业,确保我国硝酸工业健康有序地发展,加快从硝酸生产大国向强国迈进的步伐.