This paper presents a detailed thermodynamical exergy analysis of an optimized MSF DISTILLATION plant based on the latest published thermodynamics properties of water and seawater software of the Massachusetts Institute of Technology by using design and optimized plant operation data. Exergy flow rates are evaluated throughout the plant and the exergy flow diagram is prepared in both cases. The rates of exergy destruction and their percentages are indicated on the diagram so that the locations of each exergy destruction can easily be identified. The study concludes that as a result of an optimization, making the (MSFD) unit once-through cooling system to recirculating type by using cooling tower system, the unit's exergy destruction pattern changes meaningfully. Besides, in the three exist thermal desalination plants up to 53 percent of feed water, i.e.; 667 m3/h and the same amount of reject water can be conserved. Though, with this modification, the unit steam consumption has been increased up to 13 ton/h, about 50 percent of design. Moreover, the detail of the study showed that the exergy destruction can be reduced more than 39% in the pumps, and 30% in blowdown and around 29% in distillate streams. For brine heater, an enhance as small as 0.37% is also achieved. In the other hand, the rate of destruction of exergy increased around 25% in the cooling process and above 5% in the evaporators.

In the multi stage FLASH DISTILLATION type of brackish water desalination, the main stream supply feed water is rejected. This water actually is the cooling water which adsorbs the latent heat of vapors of the recirculating boiling brine in the heat rejection evaporator and leads to produce distillate water. In the industries like petroleum refineries, which are located beside the rivers, raw water after pretreatment and clarification with coagulants and other chemicals, now named clarified water, goes to water desalination plant as feed water. The return of more than 50 percent of the treated water to the river with around 14oC temperature increase which is not acceptable and considered as waste. Nevertheless, by using cooling tower system, it can be recycled in this process. This paper represents optimization of water desalination process in a petroleum refinery as a case study, where for the first time; the result of this study has been performed. In this research, it is clearly shown that how by using of proper data gathering, modeling and simulation of process with appropriate use of equations and employment of the basic concepts of thermodynamic a significant saving can be achieved. It is found that for each of three exist thermal desalination plants up to 52 percent of feed water, i.e.; 667 m3/h and same amount of reject water can be conserved. Though, with this modification, the unit steam consumption has been increased up to 13 ton/h, about 50 percent of design.

In this work, a new process design and clean production to increase the yield of steam DISTILLATION of rosemary essential oil was studied. For extraction of essential oil, a packed bed of rosemary was exposed to the steam flow. For improving the total yield, multistage bed column was used. The effects of steam flow rate, height of plant bed, multistage beds and time of extraction on yield and composition of the oil were studied.Also, trend of three major components of the oil during different extraction times and conditions were observed. We determined minimum steam to be passed through the packed bed so that there is minimum water in the DISTILLATION and hence, steam channeling phenomenon was overcome. Furthermore, we obtained optimum steam flow rate and time for extraction of the oil. Using a multistage column with suitable steam redistributors results in reduction of pressure drop, and steam channeling in the column, hence, increacing the yield of extraction. This research revealed different behaviors of the main components of rosemary oil; a-pinene, 1, 8-cineole and camphor in treating with amount of steam flow rate.

Essential oil of Valeriana officinialis L. cultivated in Iran was extracted using steam DISTILLATION technique and then analyzed by gas chromatography and gas chromatography-mass spectrometry. Optimization of extraction of essential oil was performed using this technique. The extraction yield results for steam flow rates of 4, 7 and 9 L/min for a packed bed of 100 gram of plant were found to be 0.60, 0.52 and 0.47 percent, respectively. For bed heights of 35, 47.5 and 65 cm and a steam flow rate of 4 L/min the extraction yield was found to be 0.60, 0.36 and 0.24 percent. The results of multistage column for a total of 100 g packed bed and 4 L/min steam flow rate were 0.65, 0.65 and 0.6 for three, two and one stage DISTILLATION column, respectively. The oil yield was increased from 0.6 for standard roots to 0.7 for crushing roots.

In the present investigation, the influences of heat exchanger replacement in Abadan Oil Refinery Company were investigated on gas consumption and performance of FLASH drum vessel. The results showed that gas consumption was increased by 3.3 percent and value of vapor generation by FLASH drum vessel 62 percent was decreased. On the other hand, the temperature of preheated crude oil as an important parameter was decreased. It decreased from 223oC to 220oC after revamping. This study shows energy consumption and environment pollutions created by these changing.

Purpose: Students are presented with a variety of case formulas to promote the development of clinical reasoning.Methods: 120 third-year medical students at our medical university were randomly assigned to 18 small groups. After each ICM (Introduction to clinical Medicine) course, they were given a paper case. A few days later small group sessions were formed and students asked tutors some questions to have more history and physical examination data and discussed and developed a differential diagnosis list. Then, all small groups met in a large group session for further discussion. After that, back to small groups, students ordered preclinical tests and they were given the results by tutor. At this stage, each group tried to further narrow the differential diagnosis list and to determine the most probable diagnosis. Finally, in the large group session a consensus diagnosis was reached after reflective observation. A questionnaire was used before and after intervention. The small group tutor rated student's abilities at the end of first day and last day.Results: The attitude of students about the positive effects of MPCD increased significantly from the first day to the last day (P<0.05). The progress checklist of the student's abilities showed a statistically significant improvement post intervention.Conclusion: Our study suggests that using MPCD method is an effective way to increase clinical reasoning skills of medical students.