Process Flow Diagrams of Cryogenic Double-Wall Tanks for LNG Storage

Chemical and Petroleum Engineering - Three process flow diagrams of vacuum insulated cryogenic double-walled LNG storage tanks are analyzed. The aim of the research is to exclude the spillage of...     

大型LNG储罐内压力及蒸发率的影响因素分析

LNG在储罐内的蒸发对LNG储罐的安全有着非常大的影响。为此,以3×104m3的LNG储罐为例,在分析研究的基础上,基于质量守恒及能量守恒原理,建立了预测LNG储罐内压力及蒸发率的模拟模型,经试验验证该模型的计算结果较为准确可靠。利用该模型分析了密闭LNG储罐内压力及蒸发率的影响因素。结果发现:密闭LNG储罐存在1个"最优直径"和"最优充满率";LNG储罐保温层导热系数越大,LNG储罐内压力上升得越快,LNG安全储存时间就越短;环境温度越高,密闭LNG储罐的压力上升得越快,LNG安全储存时间越短;LNG含氮量、外界大气压对LNG储罐内的压力影响不大;LNG含氮量越高其的蒸发率越低,向LNG储罐内充注氮气可以有效地降低LNG储罐内液体的蒸发率。该项成果将为LNG储罐的设计及运行提供技术支持。     

储罐氮封系统失效原因分析

储罐氮封系统是利用氮气在封闭的储罐气体空间形成一种微弱的正压装置,目的是防止储罐内储存介质与空气中的氧气接触,使之与外界隔绝,防止产品的氧化变质,另外通过保持储罐的微正压避免罐顶及罐壁变形。但是,氮封系统使用过程中会出现失效情况。这就要通过对氮封系统保护的介质性质、氮封系统安装、氮封阀结构和材质、环境等方面进行分析,从而采用最佳的方案,确保氮封系统完好运行。     

Negative Viscosity Anomaly of Liquid Petroleum Products after Heat Treatment

Heat treatment is a common method of improving the properties of heavy crude oils and petroleum products. Measurements showed for the first time that after heat treatment at 28—40°C, the rheological parameters of petroleum systems become much worse. The results obtained are important for improving shipping and storage technologies in conditions of periodic temperature drops. A theoretical explanation of these effects is given with consideration of the phase diagrams of petroleum systems and thermally induced changes in their colloidal structure.     

液化天然气低温储罐吹扫干燥方法及应用探讨

液化天然气(LNG)储罐投产前要进行干燥,干燥不合格可能造成储罐冷量外漏,甚至管道、阀门堵塞。介绍了LNG储罐干燥的2种置换介质和2种吹扫方式及其单独、配合使用的优点和特点。针对合肥燃气10000 m 3双壁LNG储罐实施的分区吹扫干燥,即干空气+氮气为置换介质、持续式吹扫+升压式吹扫相结合的吹扫操作,分析了储罐底部干燥不达标、露点下降不明显的原因,提出并实施了加热氮气和提高氮气流量2条整改措施。监测数据分析表明,整改取得了较为满意的效果,对其他LNG储罐工程的吹扫、预冷有一定的借鉴意义。     

Nucleotide degradation and quality changes in mullet (Liza corsula) and pearlspot (Etroplus suratensis) in ice and at ambient temperatures

Quality changes in Mullet (Liza corsula) and Pearlspot (Etroplus suratensis) stored at ambient temperature and in ice were studied by sensory, nucleotide and volatile base nitrogen analysis. The K-value increased linearly with storage time and appeared to be a good index of freshness for the two brackish water fish. Inosine monophosphate bears a significant positive correlation with (P ≤ 0.001) flavour score. Hypoxanthine increased exponentially with time and volatile base nitrogen showed a slow increase during the early periods of iced storage.     

储气库井油套环空注保护液和氮气柱对比

为了有效解决地下储气库注采过程中管柱内外压力变化给管柱安全性带来的问题,针对地下储气库气井管柱注采过程中温度、压力的波动特征,采用热力学与传热学理论,根据环空注满保护液与环空注入一段氮气柱2种情况分别建立了储气库管柱内外压力平衡模型,分析计算了2种模型的管柱内外压力及变化差异,重点研究了环空注氮气柱的最佳长度,绘制了氮气柱长度与封隔器下入深度最佳组合图版。研究结果表明:相同条件下环空注氮气可将注采过程中环空压力减少50%~90%,最佳氮气柱长度为封隔器下深的1/20~1/15;氮气柱长度越长,环空压力值越低;油管流体温度、油管内压力的敏感性分析表明,温度对环空压力变化影响较大;油套环空里注入合理的氮气柱长度可以防止储气库井管柱破坏和封隔器失效。     

苏里格气田凝析油稳定工艺和安全储存技术

凝析油的储存安全直接影响气田的安全生产,文章以苏里格气田第三天然气处理厂为例,探讨凝析油的稳定工艺及安全储存技术。为提高凝析油储存的安全性。稳定凝析油内浮顶储罐采用氮封措施,并介绍了氮封方案及投用氮封系统时的注意事项。     

盐穴地下储气库氮气阻溶管柱腐蚀寿命预测

为分析盐穴地下储气库氮气阻溶条件下管柱的氧腐蚀情况,预测其服役寿命,通过室内高温高压腐蚀失重试验,研究氮气纯度对N80管材的气液两相腐蚀规律,并结合X射线荧光光谱(XRF)分析、X射线衍射(XRD)分析、 扫描电镜(SEM)分析等表面分析技术对腐蚀产物进行表征分析.最后基于均匀腐蚀速率对管材的腐蚀寿命进行预测.研究结果...     

IDENTIFICATION OF NITROGEN COMPOUNDS AND THEIR EVOLUTIONDURINGAGEING NABSENCE ANDPRESENCE OF ADDITIVES EFFICIENCYOFHYDROTREATMENT

Abstract

As established by several previous works, nitrogen compounds play a prominent role in the evolution of middle distillates containing cracked components, particularly regarding sediment formation and color evolution.

In a first part, this paper describes and compares stability properties of fuel blends using both an accelerated ageing method at 120°C (248°F ) and long term storage methods at 43°C(110°F) -ASTM 0 4625 - and at ambient temperature. Effectiveness of stabilizing additives is also evaluated. In mixtures containing LCOs, insoluble products are formed progressively during ageings, more or less rapidly according to the chemical constitution of the mixtures.

Then, it reports the complete identification of nitrogen compounds using gas chromatography equipped with a selective nitrogen detector and mass spectrometry showing that in light cycle oils, alkyl indoles and carbazoles are the main families.

Evolution of these compounds was followed kinetically during ageings in absence and presence of additives and alkyl indoles appeared as the moat evolutionary.

It appeared that some additives avoided evolutions of alkyl indoles without preventing sediment formation and color evolution. Oxidation mechanism involving nitrogen compounds should not be the only one to explain the storage evolutions of middle distillates.

Hydrotreatment converts all the alkyl indoles of LCO and prevents coloration end deposits in the storage of the mixtures of steaight-run distillates and LCOs.     

THE ROLE OF HETEROATOMS IN JET FUEL INSTABILITY

ABSTRACT

The test fuel used in this investigation was a petroleum derived jet A fuel from Rastanura refinery, Saudi Arabia. The physical and chemical tests of fuel, and one month sunlight storage experiment exhibited the stability of fuel. Accelerated and ambient storage stability tests, conducted using model nitrogen compounds in jet-A fuel and n-decane, indicated that the rate of sediment formation was dependent on the structural features of nitrogen compounds and storage conditions. The pyrrole and indole derivatives did not produce any appreciable sediment except 2,6-dimethylpyrrole. Air, temperature, dissolved oxygen and light all strongly accelerate the process of sediment formation. On the other hand removal of dissolved oxygen significantly reduces it. Acids and phenols act respectively as accelerator and inhibitor towards sedimentation. The reaction has a low apparent activation energy and appears to involve a free radical oxidative self condensation of nitrogen compounds. The tower O/C ratios of sediment also supported the view point that oxidation is a key aspect of jet fuel thermal instability. Approximately 25 different types of possible structures were identified from average properties of sediments as analysed by elemental analysis, infrared and mass spectrometric methods.     

IDENTIFICATION OF NITROGEN COMPOUNDS AND THEIR EVOLUTIONDURINGAGEING NABSENCE ANDPRESENCE OF ADDITIVES EFFICIENCYOFHYDROTREATMENT

As established by several previous works, nitrogen compounds play a prominent role in the evolution of middle distillates containing cracked components, particularly regarding sediment formation and color evolution.

In a first part, this paper describes and compares stability properties of fuel blends using both an accelerated ageing method at 120°C (248°F ) and long term storage methods at 43°C(110°F) -ASTM 0 4625 - and at ambient temperature. Effectiveness of stabilizing additives is also evaluated. In mixtures containing LCOs, insoluble products are formed progressively during ageings, more or less rapidly according to the chemical constitution of the mixtures.

Then, it reports the complete identification of nitrogen compounds using gas chromatography equipped with a selective nitrogen detector and mass spectrometry showing that in light cycle oils, alkyl indoles and carbazoles are the main families.

Evolution of these compounds was followed kinetically during ageings in absence and presence of additives and alkyl indoles appeared as the moat evolutionary.

It appeared that some additives avoided evolutions of alkyl indoles without preventing sediment formation and color evolution. Oxidation mechanism involving nitrogen compounds should not be the only one to explain the storage evolutions of middle distillates.

Hydrotreatment converts all the alkyl indoles of LCO and prevents coloration end deposits in the storage of the mixtures of steaight-run distillates and LCOs.     

THE ANTI-STRIPPINC PROPERTIES OF BASIC NITROGEN IN HYDROCRACKED RESIDS

ABSTRACT

The hydrocracked residues were found to be considerably enriched both in total nitrogen and in basic nitrogen relative to total nitrogen with respect to the feed asphalt. The matrix in which these basic nitrogen components are most likely to be found consisted of compact aromatic structures containing relatively few naphthenic and paraffinic moieties

Upon hydrocracking, the basicity of the remaining basic nitrogen increased with the level of conversion. It is this increased nitrogen basicity which most probably accounted for the enhanced anti-stripping properties of the hydrocracked residues.

Hot storage, such as could be expected during the transportation of the paving asphalt, resulted in the apparent loss of approximately 10%, on average, of basic nitrogen without a commensurate decrease in the anti-stripping effectiveness of the additive. Possible explanations lie in the chemical reactivity of the asphaltic binder

Attempts at isolation of a basic nitrogen concentrate have met with a modicum of success. Indications are that the nitrogen compounds extracted depend largely on the method of extraction     

储存对柴油润滑性的影响

采用高频往复试验法（SH/T 0765#-2005）对不同来源的市售成品柴油的润滑性进行评价,比较储存前后润滑性的变化。考察了硫含量、多环芳烃含量、酸度和碱性氮化物类型对柴油储存前后润滑性能的影响。实验结果表明：不同柴油储存前后润滑性变化情况不同,凝点低的柴油储存后润滑性变差的几率较大;低硫含量、低芳烃含量的柴油储存前后润滑性差异较大;储存后柴油的酸度增大、缺氢数小的碱性氮化物含量增多是导致柴油润滑性变好的原因;脱除胶质后的柴油润滑性有所降低     

大型石油储罐主动防护系统氮气溢出分析与测试

针对大型石油储罐主动防护系统在主动保护过程中氮气从二次密封装置溢出的情况,建立了氮气扩散模型,进行了溢出源强、蔓延系数、溢出高度的分析计算和确定,采用Matlab软件对氮气溢出扩散进行了仿真模拟分析。通过分析进行了氮气溢出安全状态的评价,得出氮气在主动保护过程中溢出不存在致伤区域和致死区域,对人体几乎无影响的安全结论。同时,采用实体模型测试了在最不利扩散状态下的氮气溢出情况,结果表明氮气的泄漏强度远小于仿真分析时的泄漏强度,对泄漏源附近的人体安全不会造成影响。最后,通过现场实罐的测试,阐述了现场实际油罐上的气体溢出测试情况,评价了大型石油储罐主动防护系统的先进性、实用性和安全性。     

Physicochemical and microbial changes during storage of smoke-flavoured salmon obtained by a new method

The aim of this study was to evaluate the effect of a new smoking-salting method employing water vapour permeable (WP) bags on the physicochemical and microbial quality of smoke-flavoured salmon in refrigerated storage. Fresh salmon was subjected to a smoking process in the WP at 5 °C. Physicochemical and microbiological analyses were periodically carried out during the subsequent 40 days of refrigerated storage of the product. The WP bags enabled the evaporation of the exudate during the smoking-salting stage, enabling the drying of the product to take place at the same time. A slight increase of trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) contents was observed over the storage period. The concentration of TVB-N ranged from 14.26 to 21.48 mg N/100 g of fish, values far below the upper limits of acceptability. The low values of the thiobarbituric acid (TBA) index (final level of 0.71 mg MDA/kg) indicate that the lipid oxidation in the smoke-flavoured salmon was limited throughout the period studied. The initial K₁-value was high and only a slight increase was observed during storage. Counts of mesophilic, psychrotrophic, Enterobacteriaceae and lactic acid bacteria were low throughout the study. Given the changes observed for the physicochemical and microbiological parameters, it can be said that no spoilage took place in the smoke-flavoured salmon during the 40 days of storage. This new method could be of interest to producers as it enables smoke-flavoured salmon to be produced to a good standard of hygiene, minimizing handling and reducing processing steps and brine wastes.     

苯乙烯储存聚合原因分析及控制措施

针对苯乙烯储存过程中聚合物超标影响产品储存质量的问题,阐述了苯乙烯聚合的机理和聚合危害,分析了储存温度、阻聚剂含量、氧含量、储存设施等因素对苯乙烯聚合的影响。并结合生产实际,从储存温度控制、储罐内防、阻聚剂含量、优化氮封和工艺操作等方面,提出了抑制苯乙烯聚合的控制措施。     

地下含水层储存氢气的可行性分析

目的氢气的安全、高效储存对清洁能源工业化发展具有重要意义;地下含水层分布广泛、储存潜力巨大,是安全、高效地下储存氢气的潜在体。对地下含水层储存氢气的可行性进行了分析。 方法通过调研国内外关于地下含水层储存氢气的文献,在明确氢气的物理化学性质对含水层影响的基础上,分析了现有氢气地下储存的案例,探索了多种因素对含水层储存氢气的影响。 结果碳酸盐和硫酸盐胶结物含量低的砂岩以及盖层不含方解石的地质条件更适合氢气地下储存,在富有黏土矿物的储层中储存氢气是有利的;氢气地下储存应考虑微生物的影响;二氧化碳和氮气都可以作为缓冲气体,在中国进行“双碳”目标重大战略决策的当下,应该着重进行二氧化碳作为缓冲气体的研究。 结论目前,没有地下含水层储存纯氢的实例,但是相关的数值模拟研究和影响因素分析论证了含水层中储存氢气的可行性。      

Development of Quality Index Method (QIM) scheme for spiny lobster (Panulirus argus,Latreille, 1804) stored in ice

The objective of this study was to evaluate the freshness of spiny lobster (Panulirus argus) stored on ice up to 18 days. Changes during storage were observed with sensory evaluation (Quality Index Method – QIM), pH, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), and microbiological analyses (total mesophilic and psychrotrophic count). The maximum shelf life of spiny lobster stored in flake ice at 1 ± 0.2 °C was determined with loss of freshness (sensorial, physico-chemical and microbiological evaluations). High correlation R² = 0.922 between Quality Index (QI) and storage time at 1 °C was verified. QI ranged from zero (maximum freshness) to 15 (total loss of freshness) and reached the acceptable limit for consumption (QI = 9.54), which corresponds to a period of 10 days. The microbiological results showed an increase of psychrotrophic count along the storage time. TVB-N ranged from 5.23 to 20.31 mg 100 g⁻¹, TMA-N from 1.07 to 5.72 mg 100⁻¹ and pH from 6.91 to 7.19 in the first and 18th day of storage, respectively. It is suggested that spiny lobster has to be fresh and acceptable for consumption by cooling up to 10 days.     

Removing Organic Nitrogen Compounds From Middle Distillate Fuels with a Catalyst Used as a Filtering Media

Abstract

Fuel storage instability reactions of middle distillate fuel continue to be of great interest to the Department of Defense. Unlike civilian fuel, military fuel typically remains in storage tanks for one or more years. As fuel is removed from these tanks, the tanks are subsequently filled with more recently purchased fuel. In many cases, the mixed fuel is not compatible, resulting in chemical sediment and sludge formation. This fuel incompatibility can result in chemical degradation reactions that form solids that will plug nozzles and filters and render the entire contents of the storage tank unusable. Previous research has shown that polar organic nitrogen functional groups are involved in fuel instability reactions. These organo-nitrogen compounds are difficult and expensive to completely remove during the refining process; hence, this investigation involved the removal of these compounds employing three heterogeneous catalyst systems and combinations of these systems as filtering media. An unstable fuel was treated separately with Sc₂O₃, Cu/Sc₂O₃, fullerene (F), a 1:1 ratio of Sc₂O₃:(F), and a 1:1 ratio of Cu/Sc₂O₃:(F). The composition of the filtrates after filtering with the different catalytic systems was analyzed by combined gas chromatography/mass spectrometry (GC/MS). The results of this study showed that after treating the fuel with the catalyst systems, the organic nitrogen compounds detected in the extract were 0.29% carbazoles, 18.2% indoles, and 1.0% for both pyrroles and tetrahydroquinolines, and neither pyridines nor quinolines were detected. This investigation showed that scandium oxide, which is a recycled catalyst, is capable of removing organic nitrogen compounds from fuels.