De-waxing of lubricating oil distillate (400-500 ºC) by using urea was investigated in the present study. Lubricating oil distillate produced by vacuum distillation and refined by furfural extraction ...was taken from Al-Daura refinery. This oil distillate has a pour point of 34 ºC. Two solvents were used to dilute the oil distillate, these are methyl isobutyl ketone and methylene chloride. The operating conditions of the urea adduct formation with n-paraffins in the presence of methyl isobutyl ketone were studied in details, these are solvent to oil volume ratio within the range of 0 to 2, mixer speed 0 to 2000 rpm, urea to wax weight ratio 0 to 6.3, time of adduction 0 to 71 min and temperature 30-70 ºC). Pour point of de-waxed oil and yield of wax produced were determined to show the effect of these operating conditions. The most favorable operating conditions were solvent to oil volume ratio of 1, mixer speed of 1500 rpm, urea to wax weight ratio of 5, time of adduction of 13 min and temperature of 30-52 ºC.
Developments in investment casting process—A review Pattnaik, Sarojrani; Karunakar, D. Benny; Jha, P.K.
Journal of materials processing technology,
November 2012, 2012-11-00, 20121101, Letnik:
212, Številka:
11
Journal Article
Recenzirano
Investment casting has been used to manufacture weapons, jewellery and art castings during the ancient civilization. Today, its applications include jewellery/art castings, turbine blades and many ...more industrial/scientific components. The present paper reviews various investigations made by researchers in different stages of investment casting and highlights their importance. The paper initially highlights the investigations made on pattern wax properties, effects of blending, additives and fillers. Different ways through which pattern properties (like surface finish, dimensional accuracy, etc.) could be enhanced by properly controlling the injection processing parameters are thoroughly discussed. The paper also looks into the investigations made to enhance the strength, surface finish, etc. of ceramic shell for ferrous alloys/non-ferrous alloys as well as superalloys in investment casting. Investigations made on incorporation of nylon fibers and polymer additions confirm that a ceramic shell reinforced with nylon fibers attains additional permeability compared to the one with polymer additions.
Different investigations carried out on autoclave dewaxing and microwave dewaxing conclude that the wax properties are less altered with microwave dewaxing when compared to an autoclave dewaxing. Some recent investigations carried out on pouring and post-treatment operations are also discussed in the paper. The advent and emergence of rapid prototyping in investment casting are broadly exposed in the subsequent sections of the paper. Various aspects of rapid prototyping like rapid investment casting, rapid freeze prototyping, etc., along with their advantages are projected. The emerging areas of applications of rapid prototyping like dentistry, etc., are duly discussed.
Mould cracking is a common problem in investment casting (IC) that occurs during the dewaxing process, which is caused by the difference in thermal expansion between the wax pattern and the ceramic ...mould. Therefore, appropriate modifications to the mould, waxes and hybrid heating of the materials are proposed to address this problem. This study aims to investigate the effects of silicon carbide (SiC) addition on dewaxing time and mould structural defect in two different waxes (HYFILL B289 MOD S and SIVUCH L1203) under microwave hybrid heating. For the mould fabrication, stucco (Al2O3-SiO3) was added with various amounts of SiC to improve microwave heat absorption capabilities. The modified stucco was applied on layers 3–6 to ensure that the mould was more durable and suited for the casting process. The thermal expansion of the waxes and the ceramic mould was evaluated to determine its thermal expansion mismatch. The density, porosity, thermal conductivity, and dielectric properties were characterized to evaluate the properties of modified green mould. The results showed that SIVUCH L1203 wax outperformed HYFILL B289 MOD S wax, in obtaining a crack-free ceramic investment mould with a clean internal surface. This superiority is attributed to the exceptional thermal and absorption properties of the SIVUCH L1203 wax. Furthermore, the incorporation of SiC played a pivotal role in enhancing the hybrid heating process while maintaining the density and porosity of the green moulds. This was evident by the remarkable reduction of dewaxing time by 62% with 7.5% of SiC addition, which also contributed toward improving energy savings and sustainability.
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Pilot plant evaluation of unconverted oil quality to reach Gr II and Gr III Base Oil.
•Hydrocracking pilot test to produce unconverted oil (UCO) for Base Oil feed at various conversion ...levels.•Optimization of UCO quality at various conversion levels to reach high quality Base Oil with the best yield.•Solvent dewaxing of UCO correlating to the viscosity index of the catalytically dewaxed UCO.
This paper describes the hydrocracker pilot plant operations to produce Un-Converted Oil (UCO) selective for Base Oil production while achieving the middle distillate quality. This test was carried out to optimize feed and product quality for the commercial Base Oil unit to produce high viscosity index (VI) lube oil. The main objective of this experiment was to assess the performance of the hydro-cracking (HC) catalyst at different conversion levels between 50wt% and 70wt% and evaluate the quality of the Base Oil (BO) that would be produced in the commercial unit. For the test, fixed bed reactor was packed with commercial HC catalyst with pre-treatment hydro-treating (HT) catalyst upstream. The process parameters and product yields were studied by varying the HC reactor temperature. Then, hydrocracker products i.e. total liquid product (TLP) were collected and distilled into distillates and UCO. Special emphasis was given to the UCO quality with respect to the conversion so that it can produce desired Base Oil grades of Group-II (Gr II) and Group-III (Gr III). The experimental results have shown that it is possible to produce the Base Oil on specifications even at lower conversion up to 50wt%. Details of hydrocracker pilot plant design, catalyst, operations and study results are discussed.
Two comb-type copolymers were synthesized by modifications of the maleic anhydride-α-octadecene copolymer with aniline (AMAC) and with phenethylamine (EMAC), respectively. The effects of AMAC and ...EMAC on the non-isothermal crystallization kinetics of the MEK–toluene dewaxing process were comparatively investigated. The results showed that, under the optimum process conditions, the addition of 100 ppm AMAC or EMAC could increase the yield of dewaxed oil (DWO) from 67.21% to 70.87% or 69.90%, respectively, and increase the filtration rate by 80% and 70%, respectively. The non-isothermal crystallization kinetics analysis showed that the crystallization process conformed to Mo’s equation, and the addition of AMAC and EMAC slowed down the crystallization rate of paraffin. The polarizing light microscope observations revealed that the addition of AMAC promoted the formation of snow flower-like crystals, and the EMAC addition led to the crystals having longer rods with a relatively complete morphology. This work provided useful experimental data for a better understanding of the roles of comb-type copolymer additives in the MEK–toluene dewaxing process.
Determination of wax content in crude oil Rehan, Mohammad; Nizami, Abdul-Sattar; Taylan, Osman ...
Petroleum science and technology,
05/2016, Letnik:
34, Številka:
9
Journal Article
Recenzirano
Wax deposition is one of the chronic problems in the petroleum industry. The various crude oils present in the world contain wax contents of up to 32.5%. Paraffin waxes consist of straight chain ...saturated hydrocarbons with carbons atoms ranging from C18 to C36. Paraffin wax consists mostly with normal paraffin content (80-90%), while, the rest consists of branched paraffins (iso-paraffins) and cycloparaffins. The sources of higher molecular weight waxes in oils have not yet been proven and are under exploration. Waxes may precipitate as the temperature decreases and a solid phase may arise due to their low solubility. For instance, paraffinic waxes can precipitate out when temperature decreases during oil production, transportation through pipelines, and oil storage. The process of solvent dewaxing is used to remove wax from either distillate or residual feedstocks at any stage in the refining process. The solvents used, methyl-ethyl ketone and toluene, can then be separated from dewaxed oil filtrate stream by membrane process and recycled back to be used again in solvent dewaxing process.
•PM280 has both higher oil rejection and permeation flux than PMS600.•The optimum pressure of the PM280 is around 3.5 MPa.•PMS600 can largely overcome the shortcomings of asymmetric membrane flux ...decline.•Adsorption is the control step of PMS600 and diffusion is the control step of lube oil passing through PM280.
Growing standards in energy and the environment requires energy-saving technology in organic solvent purification. Membrane technology offers an alternative to energy-intensive conventional separation processes for solvent recovery, for example, the recovery of dewaxing solvents from lube oil filtrates, which is a typical example of the “de-bottlenecking” of a traditional process. In this study, lubricating oil dewaxing solvent recovery by two nanofiltration membranes was studied. The membranes used are commercially available membranes with molecular weight cutoff 280 and 600 Da (PM280 and PMS600). In order to understand the entire membrane separation process and study the mechanism of membrane separation, the structures of the two membrane materials and the adsorption and diffusion behavior of lubricant oil components on and in these two materials were studied by using the molecular simulation method. The results explain some phenomena in the experiment and indicate the separation mechanism of the two membranes.
