柴油润滑性的机制研究

利用作者从事柴油润滑性研究与检测工作十年来积累的大量数据,将柴油的常规理化分析指标以及质谱分析结果与柴油润滑性的相关性进行归纳总结,探讨柴油润滑性的机制。结果表明:脱硫工艺过程与柴油的润滑性有很好的相关性;磨损对某些含硫物质的多少并不敏感;柴油中氮含量越高,润滑性越好;柴油的黏度和密度越大,润滑性越好;馏出点温度越高,馏分的润滑性越好;饱和烃中的链烷烃和环烷烃对润滑性起负作用,而非饱和烃对润滑性有贡献,在芳烃组分中,多环芳烃比单环芳烃对提高润滑性的贡献大。     

柴油润滑性与其组成关系的研究

研究直馏柴油、催化柴油及加氢精制柴油的组成变化和其润滑性的关系,考察柴油的馏程、90％馏出温度与其润滑性的对应关系。结果表明,催化柴油的润滑性能最好,直馏柴油的润滑性能次之;对于加氢柴油,随着加氢深度增大,柴油抗磨性能变差;柴油中某些能改善其润滑性的组分,多集中在高馏程中;柴油90%馏出温度与柴油润滑性线性相关性较好,柴油中的有效抗磨组分多集中在重组分中,重组分含量增加,柴油的抗磨性能变好。     

我国柴油润滑性检测方法标准的发展与变化

2005年之前,我国一直参照国际标准ISO 12156-1-1997《柴油高频往复设备(HFRR)用润滑剂性能评定.第1部分：试验方法》进行柴油润滑性试验,直至2005年9月发布实施了我国的第一个柴油润滑性试验方法：SH/T 0765-2005《柴油润滑性评定法(高频往复试验机法)》,经过多年的积累和我国的实际情况,对第一版试验方法加以调整修改,于2022年5月实施了第二版试验方法NB/SH/T 0765-2021《柴油润滑性的评定高频往复式试验机法》。结合工作实际,对我国两次发布的试验方法加以归纳总结和分析。     

直馏柴油的润滑性和抗磨损性能

柴油是柴油发动机燃料供给系统的润滑剂,其润滑性影响发动机动力性和经济性.采用高频往复试验,研究了国产直馏柴油的润滑性,采用SRV模拟试验和柴油发动机喷射系统台架试验, 研究了国产直馏柴油的抗磨性能.结果表明,低硫低润滑性的柴油会导致发动机柱塞偶件严重磨损,而高硫低润滑性也可能导致柴油发动机高压喷射系统出现严重的磨损,应根据柴油发动机抗磨损需求, 研究提出柴油润滑性指标.     

柴油成膜润滑机制探讨

柴油是发动机燃料供给系统的润滑剂,其润滑性非常重要。在高频往复试验机上对不同柴油样品进行了润滑性评价,对试验后的金属件进行磨斑表面分析,通过对比研究,探讨了柴油成膜润滑机制。结果表明,柴油成膜组分少,不能形成良好润滑保护膜,或者因腐蚀反应不能形成有效润滑保护膜,是柴油润滑性差并导致偶件磨损的原因。     

浅析HFRR测定柴油润滑性操作难点

分析用高频往复试验机法（HFRR）测定柴油润滑性操作难点,对正确操作高频往复试验机及准确测定柴油润滑性有指导意义。     

国产柴油润滑性改进剂工业应用取得重大进展

近日，燕山石化与石科院合作开发的用于低硫柴油生产的国产柴油润滑性改进剂JT16已完成工业应用试验。目前，燕山石化已使用该剂累计生产京标IV柴油7000t。经检测，加剂柴油在其他相同条件下润滑性改善情况与进口润滑性改进剂相当，但酸度不增加。     

基于SRV磨损试验机评定柴油润滑性能评定

采用SRV线摩擦磨损试验机考察柴油的润滑性与柱塞偶件磨损的相关性。结果表明,低硫（S含量wS≤500 μg/g）低润滑柴油润滑时柱塞偶件磨损比较严重,其润滑性与柱塞偶件磨损没有相关性;高硫低润滑柴油的承载能力较高,其润滑时柱塞偶件磨损相对较轻,且润滑性与柱塞偶件磨损相关性较好;适量的酸性组分有助于提高柴油的润滑性和承载能力。部分直馏工艺生产的高硫含量柴油虽经HFRR测试润滑性较差,但在适量酸性组分、较高运动黏度共同作用下,实际SRV测试时并未出现严重的磨损。     

生物柴油调合燃料润滑性能的研究

对不同来源的生物柴油、车用柴油及其生物柴油调合燃料的润滑性能及影响因素采用高频往复试验机法(HFRR)进行研究,认为不同原料的生物柴油其调合柴油燃料的润滑性能存在差异;生物柴油的精制深度会减弱调合柴油燃料的润滑性能;生物柴油体积分数大于20%的调合燃料其润滑性基本与纯生物柴油达到一致;生物柴油体积分数为5%的调合燃料中超标的水含量会降低其润滑性能,但幅度不大,其润滑性主要由5%的生物柴油决定,抗氧、防锈剂、流动改进剂不影响润滑性能;与车用柴油不同,生物柴油调合燃料的运动黏度与磨斑直径没有很好的对应关系。     

基于SRV磨损试验机的柴油润滑性能评定

采用SRV线摩擦磨损试验机考察柴油的润滑性与柱塞偶件磨损的相关性。结果表明,低硫(S含量wS≤500μg/g)低润滑柴油润滑时柱塞偶件磨损比较严重,其润滑性与柱塞偶件磨损没有相关性;高硫低润滑柴油的承载能力较高,其润滑时柱塞偶件磨损相对较轻,且润滑性与柱塞偶件磨损相关性较好;适量的酸性组分有助于提高柴油的润滑性和承载能力。部分直馏工艺生产的高硫含量柴油虽经HFRR测试润滑性较差,但在适量酸性组分、较高运动黏度共同作用下,实际SRV测试时并未出现严重的磨损。     

Boundary lubrication of low‐sulphur diesel fuel in the presence of fatty acids

This paper presents an overview of the effect of aliphatic acids on the tribological properties of selected hydrocarbons and petroleum fractions. The major experimental part of the work focuses on improvements to the lubricity of low‐sulphur diesel fuel. Experiments were carried out using a pin‐on‐disc friction machine and HFRR test rig. The wear results obtained clearly show a specific effect of the test acids dissolved in hydrocarbons in the concentration range 0.005–0.1% (50–1000 ppm). Although the overall picture presented by these results is very complex, it can be concluded that a very small amount of the selected acids dramatically improves low‐sulphur diesel fuel lubricity.     

Development of laboratory tests to predict the lubricity properties of diesel fuels and their application to the development of highly refined diesel fuels

In the last few years there has been an increasing requirement for the provision of environmentally benign diesel fuels. However, the introduction of such fuels into service has been associated with high levels of field failure of rotary distribution fuel pumps due to wear. This is because the refining processes necessary to produce ecologically acceptable fuels result in greatly reduced levels of sulphur compounds, aromatics, and polar material, many of which are potential lubricity agents. This paper describes the development of bench test methods to evaluate diesel fuel lubricity and thus enable the identification of appropriate ‘solutions’. It has been found that the key to obtaining good correlation between field experience and bench tests is (1) to reproduce the thermal conditions present in operating pump contacts and (2) to ensure that the same mechanisms of wear operate in the bench test as in the pump environment. The physical and chemical processes involved in the lubrication of fuel pumps and the influence of temperature on these processes are outlined. As a result of the work described in this paper, effective additive solutions have been discovered for controlling the failure of diesel fuel pumps in the field and a provisional ISO (ISO/TC 22 / SC 7 M595: ‘Diesel engines - diesel fuel - performance requirement and test method for assessing fuel lubricity’) and CEC test method for assessing diesel fuel lubricity has also been developed.     

HFRR lubricity response of an additized aviation kerosene for use in CI engines

To reduce their fuel related logistic burden, NATO Armed Forces are advancing the use of a single fuel for both aircraft and ground equipment. To this end, F-34 is replacing distillate diesel fuel in many applications. However, tests conducted with kerosene on High Frequency Reciprocating Rig, showed that it causes unacceptable wear due to the poor lubricity of aviation fuel. In order to make this type of fuel compatible with direct injection compression engines, tests were carried out with ten mono–carboxylic acid esters to improve the lubricity of kerosene. Tribological results showed that all esters tested, were suitable for increasing the kerosene lubricity to a satisfactory level. Among the esters of the same molecular type, those having the ester group around the middle of the molecule appear to have better lubrication performance.     

Bio‐diesel lubricity: correlation study with residual acidity

Bio‐diesel has been accepted as a renewable liquid biofuel worldwide. In order to ensure customers' acceptance, standardisation and quality assurance are the key factors to the market introduction of bio‐diesel as a transport fuel. Lubricity of bio‐diesel is an important issue and it is well reported that 1–2% bio‐diesel is sufficient to maintain the lubricity of diesel even of very poor lubricity. However, a wide variation in lubricity performance of bio‐diesel from different vegetable oils and sources has been noticed. In addition, on critical examination, it was noticed that the variation in the lubricating performance of bio‐diesel could be better linked to its residual acidity than to variation in fatty acid composition. Copyright © 2007 John Wiley & Sons, Ltd.     

Preparation and evaluation of vegetable oil derived biodiesel esters as lubricity additives

Various vegetable‐oil derived esters using methyl, ethyl, butyl, and 2‐propyl alcohols were prepared and tested as diesel fuel lubricity additives in a roller‐on‐cylinder lubricity evaluator. At1% additive treat rate, the canola methyl and 2‐propyl esters, the best‐performing esters, increased the lubricity number of a reference fuel by 60%. Statistical analyses indicated strong effects of fatty acids and alcohols on the wear, friction, and lubricity number of the fuel. While no single fatty acid was identifiably responsible for the wear reduction, certain non‐linoleic compounds correlated with the wear data in a semi‐log relationship. The low‐temperature behaviour of the biodiesel was studied using differential scanning calorimetry. The major transitional peak temperature of the biodiesel esters changed with the melting points of their primary fatty acids, and decreased with the lengthening and branching of the tail alkyl groups.     

Effect of anti‐oxidants on the lubricity of B30 biodiesel–diesel blend

Biodiesel is used in many countries as blends with diesel fuel. However, the main obstacle in biodiesel/diesel blends acceptance, commercialization worldwide and using higher blends seems to be its ability to oxidise and increase wear and friction of automotive parts. An experimental investigation has been carried out to analyse the effect of three different anti‐oxidants on the lubricity of palm biodiesel–diesel blend (B30) and to optimise anti‐oxidant concentration based on the performance. The three phenolic anti‐oxidants, butylated hydroxytoluene, propylgallate and pyrogallol, were tested using four‐ball tribotester for 1 h with 1500 rpm and 40 kg load, at ambient temperature. These three anti‐oxidants were used in varying concentrations of 200, 400 and 600 ppm. Propylgallate anti‐oxidant showed most effective results by enhancing the lubricity of the blend in terms of reduced wear and friction. Copyright © 2016 John Wiley & Sons, Ltd.     

The lubricity of diesel fuels

The main chemical factors influencing the lubricity of diesel fuels have been investigated by carrying out wear tests on diesel fuels, diesel fuel fractions and model fuels.It has been found that, under the test conditions used, sulphur-containing components were pro-wear. Nitrogen-containing components tended to reduce wear but only at concentrations in excess of those normally found in diesel fuels. Polyaromatic species and, in particular, oxygen-containing components, were found to reduce wear significantly at concentrations normally found in fuels.     

柴油润滑性添加剂研究

针对柴油的低硫化引起的喷油泵磨损问题,研制了一种酯类柴油润滑性添加剂。经实验室分析研究,表明研制产品具有优异的润滑性能外,同时还具有一定的抗氧、防腐作用,且具有良好的贮存稳定性以及与柴油其它添加剂的配伍性;苛刻条件下BOSCH高压油泵台架试验后,其润滑性能无明显变化,油泵无明显磨损现象,泵的输出性能没有损失,没有任何有关燃油或者润滑剂的兼容性问题。加入量仅为150~250mg/kg。