CRUDE OIL FOULING ON HEAT TRANSFER SURFACES

Hydrocarbon fouling in a petroleum refinery crude preheat train has been identified as a critical issue affecting the economy of the plant very badly. Fouling undergoes different mechanisms at different stages of heating the crude oil in the preheat train. Understanding the fouling mechanisms is essential in formulating appropriate fouling mitigation strategies. The present research focuses on the study of fouling characteristics of four different Malaysian crude oils through experiments in a pilot-scale, high-pressure and high-temperature recirculation flow loop fitted with two identical fouling probes. The procedures reported in the open literature employ very high surface temperatures. It has been identified in this study that there is a maximum surface temperature/heat flux beyond which the forced convective heat transfer regime changes to boiling regime. As the industrial preheat exchangers operate at forced convective heat transfer regime, it is therefore, necessary to carry out the experiments in the same heat transfer regime. In this study, an improved method has been developed for calibrating the surface temperature using the heater temperature measurement by the Wilson plot technique. This method enables identification of the heat transfer regimes more accurately. Maximum heat flux under the forced convective heat transfer regime was determined for each crude oil at the corresponding operating conditions. A model to determine the maximum heat flux has also been proposed in terms of the crude oil true boiling point data. A series of experiments were planned and carried out to study the fouling characteristics of different crude oils at different initial surface temperatures, bulk temperatures and flow velocities at a pressure of 50 bar. Data from each experiment were collected, processed and the resistance due to fouling was determined. The induction periods and the initial fouling rates were estimated from the fouling resistance profiles. It was observed that the induction period decreased with an increase in initial surface temperature; increased with an increase in the bulk temperature and flow velocity. It was also observed that the initial fouling rates increased with increase in initial surface temperature; decreased with increase in bulk temperature and flow velocity for all the crude oils. The experimental data were analyzed using the existing threshold fouling model. This model assumes the rate of fouling is the net effect of fouling precursor formation through chemical reaction and deposition, and removal by the wall shear. The apparent activation energy values were estimated for the crude oils at different bulk temperatures and flow velocities. It was observed that the variations in the apparent activation energy values for flow velocities of 0.4 and 0.5 m/s are insignificant and that it increased linearly with increase in the bulk temperature. The existing threshold fouling models predict an increase in the initial fouling rates with an increase in the film temperatures. Although the existing models predict the fouling rates well for increase in film temperature due to increased surface temperature at constant bulk temperature, they fail to predict the fouling rates for an increase in film temperature due to the increase in bulk temperature at constant surface temperature. A new threshold fouling model was developed to account for the effect of bulk temperature on fouling by considering the apparent activation energy as a function of bulk temperature. The new threshold fouling models for the crude oils tested were proposed. The proposed threshold fouling model has been found to be in good agreement with the experimental data

Application of Taguchi technique for Analysis of Forces and surface finish during Hard Machining of Steel EN-24 using Ceramic tool insert

The objective of this paper is to obtain optimal setting of turning process parameters cutting speed, feed rate and depth of cut resulting in an optimal value of Feed force, Tangential force & Surface roughness while machining hardened EN-24 steel with ceramic tool insert. The effect of the selected process parameters on the feed force, tangential force and surface roughness have been accomplished using Taguchi’s design of experiments approach. The results indicate that the selected process parameters significantly affect the mean & variance of feed force, tangential force and surface roughness. The percent contributions of parameters in the ANOVA table for Feed force (Fx) for Depth of cut (86.67%) has a major contribution than that of cutting speed (2.29%) and Feed rate (0.89%). Tangential force (Fy), Depth of Cut (81.47%) has a major contribution than that of Feed rate (15.24%) and Cutting speed (0.96%). Similarly the Surface roughness (Ra), has Depth of cut (58.97%) has a major contribution than that of Cutting speed (24.85%) and Feed rate (13.21%). In all these cases the interactions are not having any major contributions. The predicted optimum Feed force, Tangential force and Surface roughness are-100N, 230N and 0.96 μm. The results have been validated by the confirmation of experiment and found to be with in the range of these values

Analysis of Forces and Surface Roughness on Hardened steel with uncoated ceramic insert using Taguchi Technique

The objective of this paper is to analyze the influence of various turning process parameters such as cutting speed, feed rate and depth of cut on the Feed force, Tangential force & Surface roughness while machining hardened EN -353 steel with uncoated ceramic insert. The effect of the selected process parameters on the Feed force (FX), Tangential force (FY) and Surface roughness (Ra) have been accomplished using Taguchi’s design of experiments approach. The results indicate that the selected process parameters significantly affect the mean & variance of Feed force, Tangential force and Surface roughness. The percent contributions of parameters in the ANOVA table for Feed force (FX) for the depth of cut (87.99%) has a major contribution than that of feed rate (2.82 %) and the cutting speed (4.45%). Tangential force (FY), the depth of cut (81.56%) has a majo r contribution than that of cutting speed (3.8%) and feed rate (9.87%). Similarly the Surface roughness (Ra), has depth of cut (59.59%) has a major contribution than that of cutting speed (23.67%) and feed rate (4.64%). In all these cases the interactions are not having any major contributions

The Economic Reality of Underutilised Crops for Climate Resilience, Food Security and Nutrition: Assessing Finger Millet Productivity in India

In spite of the considerable potential contribution of neglected and underutilised crops to climate resilience, food security and nutrition; widespread adoption of these crops remains a challenge. Uptake is inhibited by poor economic performance due to low yields, compounded further by various social factors. Using farm survey data and aggregated time-series data from four states in southern India, this study examines factors influencing productivity in finger millet cultivation. A farm-level yield gap analysis is complemented by an analysis of total factor productivity (TFP) growth between 1999 and 2014 to better understand the role of research and innovation. Results suggest that there is considerable potential for improved growing practices to achieve better yields, but also education levels and technical support emerge as crucial factors for boosting finger millet productivity. The TFP analysis indicates a moderate level of growth, with a high variability and conflicting trends between states, suggesting a need to invest more in research and development, extension and infrastructure. Sustained productivity gains will require research efforts that respond to the needs expressed by farmers and that finger millet forms part of an overall strategy for sustainable intensification

Unusual landing of silver pomfret,Pampus argenteus by karali dol net at Bassein Kolliwada(Vasai)landing centre,Thane district,Maharashtra

Post monsoon fishing from 10th june to 15 th Augustis avery important period for the silver pomfret Pampus argenteus in traditional Karli dol net fishery at Bassein Kolliwada landing centre,Thane district,Maharashtra

Synthesis and characterization of spherical and rod like nanocrystalline Nd2O3 phosphors

Spherical and rod like nanocrystalline Nd2O3 phosphors have been prepared by solution combustion and hydrothermal methods respectively The Powder X-ray diffraction (PXRD) results confirm that hexagonal A-type Nd2O3 has been obtained with calcination at 900 C for 3 h and the lattice parameters have been evaluated by Rietveld refinement Surface morphology of Nd2O3 phosphors show the formation of nanorods in hydrothermal synthesis whereas spherical particles in combustion method TEM results also confirm the same Raman studies show major peaks which are assigned to F-g and combination of A(g) + E-g modes The PL spectrum shows a series of emission bands at similar to 326-373 nm (UV) 421-485 nm (blue) 529-542 nm (green) and 622 nm (red) The UV blue green and red emission in the PL spectrum indicates that Nd2O3 nanocrystals are promising for high performance materials and white light emitting diodes (LEDs) (C) 2010 Elsevier B V All rights reserve

Evaluation of trace elements and particulate matter deposition on plant foliage exposed to vehicular pollution

In recent times, highly developed metropolitan cities have progressively used biodiverse roadside plants as an eco-sustainable tool for the mitigation of air pollution. The present study has been designed to scrutinize the impact of particulate matter (PM) deposition and heavy metal accumulation in roadside plants. Some of the common roadside plants found along the national highway at Thane (Mumbai) region that were selected for this study are Alstonia schlolaris, Bauhinia variegata, Ficus benghalensis, Ficus religiosa, Cassia fistula, and Mangifera indica. The inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was carried out for five heavy metals, namely Cr, Cu, Fe, Mn and Zn. The particulate matter deposition was observed to be the highest in Ficus benghalensis (1.14 mg kg–1), while it was found to be the lowest in Bauhinia variegata (0.71 mg kg–1). The present study revealed that the accumulation of heavy metals in plants inversely varies with the deposition of dust on the surface of leaves. The tolerant species of plants can serve as natural biofilters that can alleviate environmental pollution to certain extent

Estimation of Stature from Dimensions of Foot

Background:Establishing personal identity is one of the main concerns in forensic investigations. Estimation of stature forms a basic domain of the investigation process in unknown and co-mingled human remains in forensic anthropology. The objective of the present study was to set up standards for estimation of stature from the foot length and breadth.Methods: The study samples were constituted than 120 medical students (60 males and 60 females) of Sri Devaraj Urs Medical College, Kolar. The participants were aged between 18 and 21 years. Two anthropometric measurements viz. foot length and foot breadth will be taken independently on the left foot of each individual. The results were tabulated and then regression equation was derived.Results:The correlation between stature and all the foot measurements was found to be positive and statistically significant (P value<0.001). Regression equations were derived for estimation of stature from the measurements of the foot. Conclusion:The present study indicates that anthropometric measurements of foot length and breadth are valuable in the estimation of stature. Foot length measurements estimate stature with greater accuracy when compared to foot breadth measurements