Effect of reflux ratio and number of stages on purity of ethylene in ethane-ethylene distillation using HYSYS process modeling software is presented in this paper. Results showed that purity of separation is directly proportional to reflux ratio as well as number of stages. A mixture of ethane and ethylene is pre flashed in a shortcut distillation column and parameters such as external reflux ratio, minimum reflux ratio, minimum number of stages, actual number of stages, optimal feed stage, condenser temperature, reboiler temperature and also condenser and reboiler duties are obtained. Then this feed is employed in a full scale distillation column to obtain the final results. Simulation shows that it is possible to achieve a purity as high as 99.2% using less than 100 plates, 84 plates to be precise. Optimum reflux ratio was also obtained. Results demonstrated that extra cost of using membrane systems to improve separation efficiencies can be avoided by using optimum reflux ratio in ordinary distillation.
This work investigates carbon monoxide content of smoke emitted by various local and imported cigarette brands sold in Pakistani markets. Flue gas analyzer IMR 2800-p was used to analyze the smoke by using the bottle method. Nox, Sox and lower explosion limits of smoke was also obtained. The results showed clear distinction between local and imported brands as far as CO content was concerned. Almost all of the local brands exceeded the allowable limit of 20 ppm by a large margin. Cigar was also analyzed and its CO content also exceeded the allowable limit. There is a dire need to investigate these local brands by highly efficient and precise instruments to protect the masses from their harmful effects. Because Pakistan is a poor country, consumers of local brands far outnumber those of imported brands. Cigarette smoking is in itself very harmful but smoking these local brands which don't comply with International Organization for Standardization (ISO) standards for tobacco and tobacco products and regulations can only hasten the journey towards disaster.
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