Performance Assessment of Selected Nigerian Vegetable Oils as Quenching Media in Hardening Process for Medium Carbon Steel

A comparative study was carried out to investigate the suitability of some selected Nigerian vegetable oils as alternative quenchant to SAE40 engine oil for industrial heat treatment of Medium Carbon steels. The study involved the characterization of physicochemical properties and fatty acid profile of cotton seed oil, palm kernel oil, neem seed oil and palm oil. The quenching performance of these vegetable oils was conducted at quenchant bath temperatures of 34oC, 50oC, 70oC, and 100oC. SAE40 engine oil (Standard quenchant) and tap water served as control. The effect of cooling rates of the quenching media on mechanical properties and microstructure of the quenched steel samples were investigated. The results obtained show that the different vegetable oils have different viscosity and viscosity-temperature behavior just as their molecular structures were different. The mechanical properties of the as-quenched specimens in these oils show that the hardness of steel quenched in palm kernel oil was highest 40.85HRC. As received sample absorbed the highest amount of energy (183 J) before fracture while sample quenched in water absorbs least energy (28 J). Hence vegetable oil is suitable as alternative quenchant to petroleum based SAE40 engine oil for quenching medium carbon steels, without cracking or distortion, the most suitable among them being palm kernel oil.

Identification of Heat Transfer Coefficients by Use Conditions of Quenching Oil

Heat transfer coefficients of the quench medium are necessary for heat-treatment simulation. Cooling characteristics of quenching oil vary with kinds and usage greatly. Users are selecting oil solutions that come up to their desired hardness and quenching distortion requirements. In particular cooling performance rises by agitation and decompression. Therefore we identified a heat transfer coefficient by usage and kinds of quenching oil. Cooling characteristics are different greatly by a kind of quenching oil. A difference of a cooling characteristic by a kind of oil depends on a temperature range of a boiling stage and the maximum heat transfer coefficient mainly. On the other hand, in a convection stage, there are few changes in a boiling stage. Even if quenching oil temperature is changed, heat transfer coefficients do not change greatly. When quenching oil stirred, heat transfer coefficients of vapor blanket stage and a convection stage rise, but there are a few changes in a boiling stage. When quenching oil is decompressed a temperature range of a high heat transfer coefficient moves to the low temperature side. In addition, a heat transfer coefficient in a vapor blanket stage comes down. For precision improvement of heat-treatment simulation, it is important that the heat transfer coefficient is calculated in conformity to the on-site use reality.

Oil quenched malleable iron,the strength of an old material in a “green cast” development and a new future

Malleable iron lost the interest and the development stopped in the turbulent seventies of tremendous developments of new technologies. The personal computer, emission spectrometer, thermal analysis, cold-box core system and automatic vertical moulding were introduced into the foundry industry. Experience shows that these new technologies do not always match up with malleable iron. Solidifciation and mould filling simulation programs are not always capable to handle a low carbon equivalent iron like malleable iron. Recent developments show however by using these new technologies and combined with practical experience, it is possible to increase the casting yield of malleable iron to the same level as ductile iron. The mechanical properties, especially the yield strength of malleable iron according to the standard are equivalent to those of ductile iron, however the yield strength of oil quenched malleable iron is signifciantly higher than that of ductile iron. An extensive investigation is made between ductile iron, air quenched and oil quenched malleable irons based on the properties of more than 350 test bars produced under the same conditions. The results are compared with the existing international standards and discussed. Other properties like fatigue strength and response to surface treatments as induction hardening are also discussed. The costs of malleable iron are reviewed and compared with other ferro alloys. These recent developments in increasing the casting yield, the understanding of the strength, makes malleable iron competitive with ductile iron and cheaper than the first grade of ausferritic ductile iron, or steel qualities. It is possible to design lighter and save weight which is essential in the automotive industry. An example of "green cast" development for typical applications, used in automotive transmissions and engines are shown.

乙烯装置急冷系统优化节能改造

乙烯装置急冷系统存在热量回收不充分问题,热量通过裂解气由急冷水系统回收,消耗大量循环水,造成能量浪费和能耗费用增大。对于此类低品位热能,传统方法是直接利用,但是存在热能利用率低、费用高的缺点。文中通过强化急冷油系统回收更多的高品位余热,减少低品位余热的产生。具体是引出1股急冷油作为工艺水汽提塔塔底热源,部分或全部替代塔底蒸汽,同时可以减少急冷水系统消耗的循环水。该措施具有节约蒸汽和降低循环水消耗的双重效果,改造工作量小,费用低。

浅析乙烯装置急冷油泵机械密封的选用

针对目前乙烯装置急冷油泵机械密封在现场使用效果不佳、运行寿命短的问题,根据急冷油泵的工况特点,分析了其密封难点,推荐了一种适用于乙烯装置急冷油泵的密封辅助系统方案及机械密封结构。该结构成功运用在多个乙烯装置急冷油泵上,运行稳定,使用寿命显著提升,达到了优化改进的目的。

乙烯装置急冷油黏度高的原因分析及优化处理

文章简要介绍了急冷油黏度高对乙烯装置的影响,从急冷油黏度增加机理、裂解原料组分及工艺操作方面对急冷油黏度高的原因进行了分析。结合某乙烯装置实际运行情况,分别从原料性质、工艺调整及减黏塔调整方面进行优化处理,最终使急冷油黏度稳定控制在合理范围内,并总结了急冷油黏度最优情况下的工艺参数。

液压油缸等离子弧表面淬火工艺

液压油缸作为液压机的液压执行元件,通过往复运动,输出压力和速度。因此其柱塞杆、活塞杆既要具备表面高硬度、耐磨性和疲劳极限,还要求心部具备高强度、韧性和塑性。为了满足柱塞杆、活塞杆技术性能要求,需对其外圆表面进行淬火处理。为此,改变常规采用的感应加热表面淬火工艺,率先采用等离子弧表面淬火工艺,在卧式车床上对大直径油缸柱塞杆、活塞杆进行表面淬火,取得了满意的效果。

基于ANSYS的铝合金球淬火热分析

利用ANSYS APDL有限元瞬态分析法,建立铝合金球Al-Si-Cu-Mg的有限元模型及其淬火温度场,求解后得到淬火过程中的应力场与温度场等结果。在油和水2种不同的介质下进行淬火并完成淬火过程的有限元模拟,可以观察到淬火过程中合金球各个位置的温度变化和冷却速度变化,以及在油淬和水淬2种情况下的合金球淬火过程的差异。结果表明:合金球在考虑自身重力的影响下,其底部表面位置为其所受最大拉压应力处;合金球所有位置在水冷淬火条件下的冷却速度要比油冷淬火条件下的冷却速度快;水冷淬火条件下底部的等效应力以及第一、二、三主应力都比油冷淬火条件下的受力下降的快。

大型急冷油旋液分离器进口段的极限载荷分析

采用ANSYS Workbench对大型急冷油旋液分离器的进口段进行了应力分析与强度评定,对弹性应力分析的结果进行应力分类并与相关的极限值进行比较,一次局部薄膜应力无法通过强度评定,一次加二次应力通过强度评定,然后用极限载荷分析法替代一次应力强度评定。应力分析结果表明结构的静强度和安定性均能满足要求。

阻聚剂CH 6621 A在乙烯装置急冷油系统的应用

针对中国石化北京燕山分公司乙烯装置急冷油系统的聚合物结垢堵塞问题,对碳氢联合科技(北京)有限公司生产的急冷油塔阻聚剂(牌号为CH 6621 A)进行了应用分析。结果表明:在急冷油塔塔顶汽油中,含有双烯烃、苯乙烯、芳香类烯烃、茚、茚满等多种易产生垢物的性质活泼的组分,并且组成质量分数相对较高;在装置满负荷运行的情况下,使用CH 6621 A后,急冷油塔平均压差较使用前降低0.18 kPa,急冷油塔塔顶和塔釜平均温度分别为103,185℃,较使用前均降低1℃。

大型急冷油旋液分离器的研发与应用

针对百万吨乙烯装置中急冷油与焦粒固液分离难题,采用模拟软件对直径为2 m的大型急冷油旋液分离器进行了优化设计,并对设备内部流场、性能进行了数值模拟分析,同时对设备进行了变工况特性研究,并在典型工况下将实际运行参数与数值模拟结果进行了对比。结果显示,实际运行参数与数值模拟结果一致,说明该设计方法具有很强的工程实用价值。

180万t·a^(-1)催化裂化装置急冷油投用总结

大庆炼化公司180万吨/年最初规模按180万吨/年设计,为了在2010年汽油质量达到国Ⅲ标准要求,二套ARGG装置于2009年检修期间实施了MIP-CGP技术改造。装置包括反应再生、分馏、吸收稳定、余热锅炉、烟气脱硫、气压机、能量回收、产品精制几部分组成,ARGG装置以减压渣油等重质油为原料,采用MIP-CGP专用CGP-1DQ催化剂,以生产富含丙烯、异丁烯、异丁烷的液态烃,并生产高辛烷值汽油。本装置现加工能力238万吨/年,反应部分采用全提升管反应器,再生部分采用多段供风的管式烧焦加床层完全型式。

乙烯装置急冷油除焦系统设计方案

回顾了乙烯装置急冷区急冷油中焦粒的去除,国内近30年来设计方案的变化历程;分析了各个阶段设计方案的优缺点。着重叙述了目前阶段采用自动刮刀过滤系统结合旋液分离过滤系统的除焦系统方案,可高效分离出急冷油中焦粒,具有显著的优势。详细阐述了其系统组成、结构特点和设计思路,并分析了系统的工作原理和技术特点。

金属针布齿条淬火油烟处理方法

为了减少油烟污染、改善车间环境,总结金属针布齿条在线退火和淬火产生油烟的原因,从金属针布齿条清洗装置、淬火温度、排烟装置、油烟净化、排气筒装置等方面提出油烟处理措施,并分析改善效果。指出:通过使用压缩空气和风嘴结合吹扫降低金属针布齿条表面含油量,集中供油降低油温,增加淬火油池长度提高冷却能力,采用全自动排渣离心净油机提高淬火油洁净度,采用高压静电型油烟净化设备,并在风机后端安装排气筒装置等方式,大幅减少车间油烟污染、改善工作环境,使油烟排放符合标准。

汽车雨刮器用钢片热处理研究

对雨刮器用65Mn钢片油淬火回火热处理工艺进行研究。介绍了65Mn钢化学成分以及对雨刮器用钢片的技术要求,给出雨刮器用65Mn扁钢丝工艺流程。通过试验得出最佳工艺参数:奥氏体化温度840℃,回火温度450℃,获得的产品硬度为51.2 HRC,平整度(L=500 mm)不大于0.1 mm,产品表面氧化均匀,性能符合客户要求。

热解法制备油溶性碳量子点用于土霉素的检测

以柠檬酸、谷胱甘肽和油胺为原料,采用热解法制备了油溶性荧光碳量子点(o-CDs)。该o-CDs具有良好的光化学性能以及光学稳定性,激发波长与发射波长分别为375和440 nm,量子产率为0.48。基于土霉素对碳量子点的荧光淬灭效应,建立了一种灵敏度高、选择性好的土霉素荧光检测方法,并将该方法应用于实际样品牛奶中土霉素的检测。土霉素对o-CDs的荧光淬灭程度与土霉素的浓度(0.77~16.12μg/mL)呈良好的线性关系,检出限为0.14μg/m L,牛奶样品中的加标回收率在97.13%~104.18%之间,RSD值小于5%,证实了该方法的准确性。该o-CDs有望应用于食品领域中土霉素的检测。

动态淬火介质冷却特性及换热系数的研究

为了研究工业生产条件下淬火油在不同流速下的冷却特性曲线及换热系数 ,用超声波多普勒流量计测定了淬火油槽的流速 ,按ISO9950标准测定冷却特性曲线 ,用 1 2 0mm× 1 2 0mm× 2 0mm平板状试样和反传热法测定与计算了换热系数。结果表明 ,随着介质流速的增加冷却特性曲线的冷速最大值及换热系数的最大值均呈增加趋势 ,当搅拌使介质中产生气泡时 ,介质的冷却能力明显降低。最后指出换热系数曲线能更好地反映表面热量传递的真实情况。

淬火油动态下换热系数的测量及计算

为了测量和计算工业条件下淬火油在不同流速下的换热系数 ,采用超声波多普勒流量计测定了介质的流速 ,用 12 0× 12 0× 2 0 (mm)平板状试样和反传热法测定与计算了换热系数。结果表明 ,换热系数曲线能更好地反映表面热量传递的真实情况 ;随着介质流速的增加 ,换热系数的最大值呈增加趋势 ,当搅拌使介质中产生气泡时 ,介质的换热系数明显降低。

用冷却曲线估测动态条件下淬火油的淬火烈度

对淬火油在不同流速下的冷却曲线和淬火烈度进行了测量 ,建立了硬化能力、淬火烈度与介质流速三者之间的关系。结果表明 ,淬火油的淬火烈度H值与建立在冷却曲线基础上的硬化能力HP值均随介质流速的增加而增加 ,二者增加的斜率相近。因此 ,在测得冷却曲线的前提下 。

减压深拔急冷油工艺研究

减压深拔工艺的进料温度很高,塔底渣油温度常常超过663.15 K,由于塔底重油在较高温度下容易发生热裂解、聚合反应,同时可能发生结焦,使得侧线产品质量很难达到要求,造成塔内件及塔底抽出口堵塞,甚至造成装置停车。基于于计算流体力学(CFD)理论,采用商业软件Fluent模拟2种急冷油工艺循环分布结构,对渣油液位的温度分布场进行研究。模拟结果表明,采用急冷油分布管可以有效地保证渣油的温度分布均匀,且模拟结果与工业数据进行了验证,误差不超过0.4%。而不采用急冷油分布管,塔底渣油温度分布跨度非常大,且会出现局部高温区,影响生产正常操作。