HUNGARIAN JOURNAL OF INDUSTRIAL CHEMISTRY VESZPREM Vol. 30. pp. 295 - 298 (2002) ANALYSIS OF PARAMETERS INFLUENCING THE PROPERTIES AND YIELD OF LUBE-OIL EXTRACTION PRODUCTS P. KALAICHELVI (Department of Chemical Engineering, Regional Engineering College, Trichy- 620 015, INDIA) Received: November 19, 2002 An analysis of the influence of various parameters (mainly the compositional effect of the lube feed stock and the e~traction temperature) on the percentage yield and properties of the lube oil is presented. The experiment is conducted at different temperatures in a single-stage extractor using furfural as the solvent. Based on the analysis, a correlation has been developed and verified with the experimental results. Keywords: extraction, lube oil Introduction Crude oil is distilled in atmospheric distillation column to get various useful distillates and the bottom product (residue) is taken to vacuum distillation column from which the lube oil feed stocks -are obtained as distillates. The feed stocks contain saturates, olefins, napthenes, aromatics and asphaltic components [1]. The asphaltic compenents are removed by deasphalting. Aromatic components are prone to oxidative and thermal degradation and also have poorest viscometric properties. Removal of these aromatics is needed and is done by solvent extraction. Various solvents suitable for lube oil extraction are sulphur dioxide, phenol, furfural, N-methyl pyrrolidone(NM.P), duo -sol and propane. Comparison of physical properties of the above mentioned solvents shows that NMP is an attractive solvent due to its high solvent power, low toxicity, good selectivity and adaptability [2}. However, due to the availability, low cost and high selectivity furfural is widely used for this purpose [3}. Mixer-settler, Rotating Disc Contactors, Pulsed columns and Centrifugal extractors are used for solvent extraction. Rotating Disc Contactors(RDC) shows better performance when compared with other extraction columns. However, modifying, specifying or designing as extractors from basic principles alone is unsound. Effect of various parameters including system behavior c~n only be studied through small scale equipment like smgle stage extractor [4}. Lube oil is obtained only from imported crudes. It is also well known that crude composition will change not Contact information: E-mail: kalai @rect.ernet.in only with respect to source but also with respect to time. Based on this, the compositions of lube feed stocks will also vary. Analysis of the above mentioned constrains revealed that there is a need to study the effect of various parameters mainly the effect of composition of lube base stocks on extraction yield and properties of the finished product in single stage extractor using furfural as a solvent [5} Experiments A single stage equilibrium set-up as shown in Fig.J is used for the present study. This is a cylindrical vessel with outer jacket both made of glass. This is closed at the top with a cork having provisions for thermometer, stirrer inserting and feed solvent charging. Hot oil is circulated through the outer jacket from a hot oil bath to heat the content of the vessel at constant temperature. A stirrer driven by an electric variable motor is provided for constant mixing. The bottom tapering end is provided with a stop cork for separating the two phases (bottom phase - extract and top phase - raffinate ) after extraction. The circulating bath is switched on and the temperature is set at a desired value. The lube oil feed stock and the solvent are charged in a ratio of 1: 1.4 with the help of a funnel. Then the content of the inner cylinder is heated to a required temperature and the stirrer is switched on and kept at a desired speed. Mixing is done for one hour. After mixing it is aJJowed to settle at the same temperature for one and half hour. Mixing and settling times are fixed based on the earlier 296 Table I Properties of various lube oil feed mixtures Feed Feed Mixtures Properties #4 #1 #2 #3 Density, 15 oc 0.9254 0.8979 0.8822 0.9536 0.9314 (gmlml) Pour Point CCC) +42 +42 +45 +39 +39 Kinematic Viscosity (CST) (i) 100 oc 10.37 9.1 8.3 12.58 10.49 (ii) 75 oc NA 18.44 16.42 29.90 23.25 Refractive 1.49669 1.47948 1.46888 1.51370 1.50140 Index) 75 oc Wt % Saturates 41 54.2 61.2 28.5 38.2 Wt% 59 45.8 38.8 71.5 61.8 Aromatics Motor Opening for charging /and nitrogen purging Thermometer Hotoilio """ Fig. I Single stage equilibrium setup studies in the same set-up. Then the two phases namely raffinate and extract are separately collected with the help of stop cork. Solvents present in two phases viz., raffinate and extract are recovered by simple distillation with nitrogen purging. Final traces are removed by evaporation with nitrogen purging. Properties of the feed stocks and solvent free raffinates (before and after dewaxing) and extracts are estimated based on the procedures given in ASTM standard books [6.7]. In this present work solvent/feed (S/F) ratio (by volume) is kept at 1.4 for an the cases for comparison purpose. Extraction studies are carried out for lube oil feed stock whose properties are given in Table I. To have various feed compositions. different combinations Tabl~t 1 Extraction resuJts for extraction temperatures of 65 oc and SJ F ratio of 1.4 Feed Mixtures Properties Feed #1 #2 #3 #4 RAFFINATE Yield (Wt %) 80 90 94 70 77 Density, 15 oc 0.9079 0.8856 0.8777 NA NA (gmlml) Pour Point +45 +42 +45 +39 +39 (°C) Kinematic Viscosity (CST) (i) 100 oc 9.35 8.32 8.13 10.22 9.38 (ii) 75 oc 19.31 17.40 15.82 22.33 19.50 Refractive Index, 75 oc 1.48307 1.47081 1.46475 1.49342 1.48471 Wt% NA NA NA 38.2 146.2 Saturates Wt% NA NA NA 61.8 53.8 Aromatics EXTRACT Yield(Wt %) 20 10 6 30 23 Kinematic Viscosity (CST) (i) 100 oc 26.40 NA NA 27.63 27.39 (ii) 75 oc 85.73 NA NA 98.94 94.28 Refractive NA 1.54395 1.54334 NA 1.56569 Index, 75 oc of feed + (raffinate/extract) on volume basis are mixed and properties of these mixed feed stocks are also reported along with the original feed stock [5] in Table 1. Extraction temperatures are fixed based on miscibility temperatures of various combinations of feed mixtures [2,5]. Results Results of single stage extraction of all the feed mixtures at three different temperatures are obtained in the present study. Yields and properties of raffinates and extracts at an extraction temperature viz., 65 °C, 90 °C and 110 °C are estimated and sample data are presented in Table 2 for 65 °C. Extraction results at other temperatures {90 & 110 °C) are available elsewhere [5]. Effect of extraction temperature and feed composition on raffinate yield and quality are discussed based on the results obtained. Discussion Increase in saturates content in the feed has increased the raffinate yield and quality at all extraction temperatures and decreased the extract yield (shown in Fig.2). Extractions were not carried out for the feed mixture-3 at 110 °C, since the miscibility temperatures 100 95 -e-65°C 90 -e-90°C ..-,. 85 eft. _._110 oc 1 80 u (i) 75 ·;:;.