Steam/water distillation cooling unit

While process design and equipment specification are usually performed prior to the implementation of the process, optimization of operating conditions is carried out monthly, weekly, daily, hourly, or even eveiy minute. Optimization of plant operations determines the set points for each unit at the temperatures, pressures, and flow rates that are the best in some sense. For example, the selection of the percentage of excess air in a process heater is quite critical and involves a balance on the fuel-air ratio to assure complete combustion and at the same time make the maximum use of the Heating potential of the fuel. Typical day-to-day optimization in a plant minimizes steam consumption or cooling water consumption, optimizes the reflux ratio in a distillation column, or allocates raw materials on an economic basis [Latour, Hydro Proc., 58(6), 73, 1979, and Hydro. Proc., 58(7), 219, 1979]. 

In a 500-ml three-necked flask, equipped with a thermometer, a sealed stirrer unit and a reflux condenser, place 32.5 g of phosphorus pentoxide and add 115.5 g (67.5 ml) of 85 per cent orthophosphoric acid (1). When the stirred mixture has cooled to room temperature, introduce 166g (lmol) of potassium iodide and 22.5 g (0.25 mol) of redistilled butane- 1,4-diol (b.p. 228-230°C or 133-135°C/18mmHg). Heat the mixture with stirring at 100-120 °C for 4 hours. Cool the stirred mixture to room temperature and add 75 ml of water and 125 ml of ether. Separate the ethereal layer, decolourise it by shaking with 25 ml of 10 per cent sodium thiosulphate solution, wash with 100 ml of cold saturated sodium chloride solution, and dry with magnesium sulphate. Remove the ether by flash distillation (Fig. 2.101) on a steam bath and distil the residue from a flask with fractionating side-arm under diminished pressure. Collect the 1,4-diiodobutane at 1 lO°C/6mmHg, the yield is 65 g (84%). 

Into a 500-ml three-necked flask fitted with a dropping funnel, a sealed stirrer unit and reflux condenser protected by a drying tube, place a fine suspension of 40 g (lmol) of good quality sodamide (Section 4.2.67, p. 462) in about 150 ml of anhydrous xylene. Introduce 37.5 g (40 ml, 0.4 mol) of 2-methylpyridine through the dropping funnel and rinse the latter with a few ml of dry xylene. Set the stirrer in motion and add 44.5 g (50.5 ml, 0.48 mol) of butyl chloride (Expt 5.50) over a period of 1 hour reflux the mixture with stirring for 2-3 hours. When cold, destroy the excess of sodamide by the cautious addition of 100 ml of water. Transfer the contents of the flask to a separatory funnel and discard the lower aqueous layer. Extract the xylene solution with four 50 ml portions of 1 1 hydrochloric acid. Steam distil the acid extracts to remove traces of xylene, cool the aqueous solution and render strongly alka-... 

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