Coal liquids distillation tower corrosion: Chloride pathways in the Wilsonville,Alabama SRC-I pilot plant when processing a high chloride coal

The pilot plant was operated during a three-week period with a coal containing about 0.25 wt.% chloride. During this period, samples were collected at about 20 sample points throughout the process. The mass balance and chloride content of these samples provided data to define the chloride pathway to the atmospheric distillation tower where it subsequently caused severe corrosion problems. A fortuitous processing change, made about half-way through the period, provided a marker that helped define the chloride pathway through the process. About 10% of the chloride entering the dissolver flashed overhead in the high pressure separator; this fraction remained constant even thought the total chloride entering this separator area changed by a factor of 5 to 10. In the Wilsonville plant about 50% of the total chloride entering the reactor was carried to the atmospheric tower in the highest boiling distillate process stream. Essentially all of the chloride entering the atmospheric tower was converted to iron chloride by corrosion of a lower portion of the tower.     

Coal liquids distillation tower corrosion. Analysis of SRC atmospheric distillation column samples for the presence of a highly corrosive organic chloride compound class

Samples from the Wilsonville, Alabama, demonstration plant were chemically separated into phenolic, amine and neutral fractions. Each fraction was analyzed for total chloride. The results indicate that the high corrosion rates in the atmospheric distillation tower were not due to the formation of a highly corrosive organic chloride.     

Coal liquids distillation tower corrosion: chloride analysis of solvent refined coal process samples

Severe chloride corrosion incidents have occurred in the distillation area of major direct coal liquefaction plants. Chloride analyses have been carried out for samples collected at various process streams of one of these plants (the Wilsonville, Alabama SRC-1 pilot plant) in order to define the pathway of corrosive species to the distillation area. These analyses show that the major fraction of the chloride in the atmospheric distillation tower is carried there in the higher-boiling process streams. The chloride level at a particular point in the atmospheric distillation tower may be several times that of the tower feed liquid; this concentration contributes to the catastrophic corrosion experienced in these towers. This chloride concentration provides an explanation for the occurrence of the corrosion in the last distillation tower in the process stream, rather than in the tower(s) first contacted by the chloride containing distillate stream. It also accounts for the observed localization of the corrosion within narrow regions of the atmospheric distillation tower. The chloride concentration and the chloride pathway are factors which designers of coal liquefaction distillation processes need to consider in a design that will keep corrosion to a manageable level.     

Coal liquids distillation tower corrosion: titrations relating the acidity and the corrosive chlorides

Coal-derived liquids containing chlorides have resulted in severe corrosion incidents in the distillation area of direct coal liquefaction plants. The chloride is present, in corrosive coal liquids, in an amount equivalent to the acidity that is titratable by sodium hydroxide. The curve obtained for the coal liquids titration is essentially the same as the one obtained for the titration of an amine hydrochloride solution. The corrosive chloride is exchangeable. The experimental results support the view that the corrosive species in coal liquids containing chloride are amine hydrochlorides.     

Coal liquids distillation tower corrosion: correlation of on-stream monitoring with process variables at the Wilsonville,Alabama, SRC-1 pilot plant

Corrosion incidents in the fractionation area of direct coal liquefaction pilot plants have been severe. The Wilsonville, Alabama Solvent Refined Coal (SRC)-1 pilot plant operators quickly identified chloride, a minor component of the feed coal, as a contributing factor to this corrosion. They also learned that adding sodium carbonate to the coal feed was an effective way to provide a short-term measure to reduce corrosion; however, processing conditions would not permit the addition of alkali salts in a commercial plant. The extent of the corrosion at the atmospheric distillation tower of the Wilsonville plant has been continuously monitored for over a year. The results are reported here. The corrosion behavior is correlated with operational and feedstock parameters. The information reported here provides a basis for related investigations dealing with the analysis of process samples and laboratory corrosion experiments.     

浅谈残液蒸出域的腐蚀问题

详细论述了用电石法生产氯乙烯过程中残液蒸出塔的腐蚀原因,并指明解决问题的办法,经过近年来的实践,取得了较好的效果。     

焦油蒸馏塔腐蚀原因分析及防腐措施

本文通过对包钢焦化厂焦油车间焦油蒸馏塔腐蚀原因的分析,提出了相应的防腐措施及处理方法,达到了初步的防腐效果。     

加氢裂化分馏系统的腐蚀防护思路

结合金陵石化公司炼油厂加氢裂化装置技术改造过程,分析了含硫原油加工对加氢裂化装置系统腐蚀情况,并提出相应的腐蚀防护措施.本套装置自投产以来.经历了2次炼制高含硫原油的扩能技术改造,加工原油处理量由800kt/a增加到1.2Mt/a;原油硫质量分数由0.3%～0.5%逐渐上升到平均硫质量分数1.5%左右,最高达2.5%,使本套装置加工原油的能力大大提高,同时对处理劣质原油特别是高含硫原油的设备腐蚀问题找到了一些解决办法.提出相应的应对方法和腐蚀防护思路.     

淡液蒸馏塔运行情况分析

针对淡液蒸馏塔在运行过程中出现的问题,进行计算分析,并采取了一系列改进措施,取得明显效果,确保了淡液蒸馏塔的长周期稳定运行.     

塔器技术新进展

简要介绍了塔器技术发展史及其重大变革,重点介绍了20世纪80年代后中国塔器技术的发展和现状以及存在的问题.     

乙醇蒸馏主机塔器配套规范研究

根据长期从事化工塔器及酒精(乙醇)工程科研开发的经验,并参考国内外有关文献,首先在国内开展乙醇蒸馏主机塔器配套规范的研究,内容包括96%(v/v)酒精产量为0.3～100万t/a共23个系列。     

萃取精馏法分离焦化苯中微量正庚烷精馏塔计算

根据基础研究，提出以ＤＭＦ为溶剂从焦化苯中分离微量正庚烷的萃取精馏法，并采用三对角矩阵－２ＮＮｅｗｔｏｎ－Ｒａｐｈｓｏｎ联合法对萃取精馏进行了模拟计算，取得了萃取精馏塔、正庚烷回收塔及苯回收塔的操作条件，为分离焦化苯中微量正庚烷流程提供了依据。     

氯气吸收塔腐蚀分析

根据废氯气吸收及次氯酸钠产生的工艺流程,从工艺、设备材料选择及实际使用工况等方面,分析吸收塔腐蚀原因,提出解决方法,保证设备正常、稳定、长周期运行。     

精馏塔内件的数字化设计

分析应用三维设计软件对精馏塔内件进行三维设计的基础及优势,三维设计结合强度校核软件是精馏塔内件设计的数字化方向,以填料塔二级分布槽的设计为例子,介绍三维图形技术的强大功能及其在塔内件设计中的应用.     

解吸塔及蒸氨塔的改造与计算

通过解吸塔和蒸氨塔的改造实例，应用模拟计算结果，讨论了它们各自的不同流程设计及特点。比较和分析了不同改造要求下的各设计方案。     

数字化设计技术在精馏塔器中的应用

在精馏塔器内部构件的优化与设计中采用数字化设计,实现了全塔的三维结构可视化与流体流态可视化,增强设计的可靠性和经济性。对传统的等直径急冷油回流分布管结构进行了优化,分析了其液体分布状况,得到了分布管的变孔径的分布,有效地改善了槽式分布器中液体预分布不均的状况。对桁架梁力学性能进行了研究,并比较了桁架梁和工字梁的应力、变形和挠度,结果可以看出,在相同规格下桁架梁较工字钢梁挠度和应力都大大降低,同时节省耗材1 603 kg。     

精馏塔内液体分布器的分析及改进

介绍了双氧水生产中精馏塔内液体分布器在操作时存在的问题,提出了改进措施     

减压蒸馏塔的化学清洗

研究了炼油厂加工含硫原油蒸馏装置减压塔硫化亚铁的形成,装置停工检修时硫化亚铁自燃机理及其对装置的危害。介绍了减压蒸馏塔垢样的组成;清洗此种垢样,采用的碱洗方法,清洗机理,化学清洗剂的组成;采用塔器级联循环清洗方案,有效地吸收硫化氢,确保清洗过程安全环保,清洗效果良好,无二次浮锈生成。     

Characterization of coal liquids by 13C n.m.r. and FT-i.r. spectroscopy — fractions of oils of SRC-I and asphaltenes and preasphaltenes of SRC-I and SRC-II

Coal-derived products of SRC-I liquefaction of Blacksville coal and vacuum tower bottoms (VTB) of SRC-II liquefaction of Powhatan mine coal (both bituminous and from the Pittsburgh Seam) were separated into fractions by solvent extraction. The SRC-I was first extracted with ethylacetate, and solubles were subsequently separated into oils and a mixture of asphaltenes and preasphaltenes (APA). The VTB was Soxhlet extracted with pentane to remove any residual oils, followed by tetrahydrofuran to recover APA. The APA portions were then separated by sequential elution solvent chromatography (SESC) into fractions differing in chemical functionality, and then examined by ¹³C n.m.r. and FT-i.r. spectroscopic techniques. APA are intermediates and end products of coal liquefaction. SRC-II APA are of higher molecular weight than the APA of SRC-I. The lower numbered fractions of APA of SRC-I in SESC separation have the same functional groups as the corresponding fractions of middle and heavy distillates. However, the higher numbered fractions are rich in oxygen, which is mainly in carbonyl groups. Part of the carbonyl groups are in esters which cross-link aromatic clusters. Therefore, APA and the coal itself are ‘oligomeric’ in structure, with aromatic clusters linked by carbon bridges with different functional groups. The nature of carbonyl groups in APA has been analysed in detail.     

二氯乙烷脱水脱低沸塔应用能力的分析

介绍了二氯乙烷脱水脱低沸塔操作单元的组成及工艺流程,分析了其在脱水和脱低沸物的功能应用上所遇到的一些问题,并给出了详细的解决措施。