Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53975120080101Investigation of Asphaltene Stability in the Iranian Crude Oils31211263ENJournal Article20151017<span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>The influence of different factors on the asphaltene stability in three iranian crude oils</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>was evaluated. Compositional studies and structural characterization of resins and</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>asphaltenes were carried out in order to study a possible relationship between these</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>properties and asphaltene deposition behavior. Low hydrogen to carbon ratios and</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>high aromaticities were the main characteristics of the asphaltenes from more unstable</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>crude oils. According to these results, the stability behavior of asphaltenes was</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>influenced strongly by their structural characteristics. Colloidal stability indexes such</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>as the (aromatic+resins)/(asphaltene+saturates) ratio and (aromatics+resins)/</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>asphaltene ratio do not play a key role in the asphaltene stability for the studied crude</em> <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>oils.</em></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53975120080101An NLP Approach for Evolution of Heat Exchanger Networks Designed by Pinch Technology132111264ENJournal Article20151017<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Common methods to design heat exchanger networks (HENs) by pinch technology</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>usually need an evolutionary step to reduce the number of heat transfer units. This step</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>is called loop breaking and is based on the removal of exchangers that impose</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>minimum increase on utility consumption. Loops identification and breaking is a</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>tedious task and becomes more complicated in large networks. This paper presents a</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>rapid nonlinear programming (NLP) formulation for the evolution of HENs in which</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>loop identification is not required. The objective of the NLP is the minimization of</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>HENs annual cost, which is not considered in current methods. In this method a search</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>is done to find the best units elimination of which improves HENs annual cost. The</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>search continues until the minimum number of units (MNU) is achieved and the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>exchangers that must be removed from the network are specified. The method was</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>applied to some networks reported in the literature and better results were obtained.</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Also, the convergence of the presented method is very fast and it can be applied to</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>different networks designed by pinch technology.</em></span></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53975120080101An Efficient Coupled Genetic Algorithm-NLP Method for Heat Exchanger Network Synthesis223311265ENJournal Article20151017<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Synthesis of heat exchanger networks (HENs) is inherently a mixed integer and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>nonlinear programming (MINLP) problem. Solving such problems leads to difficulties</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>in the optimization of continuous and binary variables. This paper presents a new</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>efficient and robust method in which structural parameters are optimized by genetic</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>algorithm (G.A.) and continuous variables are handled due to a modified objective</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>function for maximum energy recovery (MER). Node representation is used for</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>addressing the exchangers and networks are considered as a sequence of genes. Each</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>gene consists of nodes for generating different structures within a network. Results</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>show that this method may find new or near optimal solutions with a less than 2%</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>increase in Hen annual costs.</em></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53975120080101Cavitation Process and the Performance of Some Ferrous and Non-Ferrous Alloys345011266ENJournal Article20151017"> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>In this research an extensive literature search into the mechanism of cavitation</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>dynamics and its consequences was conducted. A cavitation venturie rig was designed</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>and constructed, and the cavitation number was checked mathematically. A new</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>camera technique was developed to capture the cavitation cloud. Carbon steel (AISI</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>1020), stainless steel (AISI 304 and 316), ferritic alloy steel (B1274), brass (C27000),</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>phosphor bronze (C51000) and aluminum bronze (C60800) test pieces were prepared</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>and tested in the venturie tube. Aluminum bronze was the most and carbon steel the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>least resistant of these alloys, the measured mechanical properties could not</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>systematically be correlated with cavitation resistance. The microscopic examinations</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>showed that cavitation induced plastic deformation had caused the misalignment of</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>polishing lines. A field study into the susceptibility of an Iranian sugar cane company’s</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>centrifugal pumps showed that deviation from the manuals hydraulic settings caused</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>cavitation and that the gray cast iron had a poor resistance. Besides the venturie tube,</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>other configurations were considered, of which an oil industry choke valve was</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>constructed and examined for cavitation.</em></span></span></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53975120080101Oil Sorption by Synthesized Exfoliated Graphite (EG)516411267ENJournal Article20151017> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>In this paper a chemical method applied to synthesize exfoliated graphite (EG) is</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>presented. In this method graphite intercalation compound (GIC) was firstly</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>synthesized by chemical treatment of graphite flakes using a mixture of sulfuric and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>nitric acids followed by thermal shock of GIC at 1000°C to produce EG. The bulk</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>density of synthesized EG was found to be as low as 4.5 kg/m3. X-ray diffraction (XRD)</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>and scanning electron microscopy (SEM) techniques were used for identification and</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>characterization of different materials. According to the XRD observations, the GIC</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>was identified as graphite bisulfate with stage 2, and residue GIC and EG had nearly</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>the same diffraction pattern, but with distinctly lower intensity. In accordance with</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>SEM results the residue graphite bisulfate was swelled in comparison with the graphite</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>flake. The oil sorption capacity of synthesized EG in this work was studied by common</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>static and dynamic tests and compared with other sorbents. The results show the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>superior capability of EG for oil spill cleanup.</em></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /></span>Iranian Association of Chemical Engineers(IAChE)Iranian Journal of Chemical Engineering(IJChE)1735-53975120080101Enhanced Degumming of Soyabean Oil and its Influences on Degummed Oil and Lecithin657311268ENJournal Article20151017e"> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>In order to study the effective factors on the quality and quantity of lecithin extracted</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>from soybean oil and the residual amount of phosphatids in degummed oil, this study</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>was arranged. Crude oil recovered from soybean which had been processed by</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>conventional solvent extraction and reached a phosphorus content of 454 ppm was used</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>for this purpose. Treatments were carried out under different concentrations of</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>phosphoric acid (zero, 0.05, 0.1, 0.2, 0.5, 2) and different percents of water ( 0.5, 1, 2,</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>5, 3, 4) at different temperatures (25, 50, 60, 75, 90 °C) and with different stirring times</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>(5,10, 20, 40, 60 min). The highest phosphatid recovery was obtained with 3 %(v/v)</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>water at 75 °C with a stirring time of 20 minutes. Adding phosphoric acid decreased</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>the phosphatid residue in the degummed oil, but the quality of lecithin was reduced.</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>However, the addition of phosphoric acid lower than 0.05 %(v /v) at 60 °C resulted in</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>the same recovery efficiency with no major effect on the quality of lecithin.</em></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /></span>