Condensers in distillation

Hydrate Natural gas and condensate in distilled and saline water and in methanol Reference Tohidi et al. (1994a, 1995b, 1996b)... 

Aluminum plate-hn heat exchangers are often used as condensers in distillation and separation processes, but they require nonfouling and noncorrosive fluids. In the chemical industry, stainless steel or welded-plate heat exchangers have been used as top condensers of distillation columns, because they can be either directly installed inside the column or closely integrated outside (Figure 39),... 

The pressure in distillation column 1 has been increased to allow feed vaporization by heat recovery (from the distillation column condenser). Inspection of the new curves in Fig. 14.9a raises further possibilities. With the proposed modification, the overheads from the... 

Kayihan, F., Optimum Distribution of Heat Load in Distillation Columns Using Intermediate Condensers and Reboilers, AfC/iS Symp. Ser., 192(76) 1, 1980. 

Hydrogen chloride released dissolves in water during condensation in the crude oil distillation column overhead or in the condenser, which cause corrosion of materials at these locations. The action of hydrochloric acid is favored and accelerated by the presence of hydrogen sulfide which results in the decomposition of sulfur-containing hydrocarbons this forces the refiner to inject a basic material like ammonia at the point where water condenses in the atmospheric distillation column. 

The material to be steam-distilled (mixed with some water if a solid compound, but not otherwise) is placed in C, and a vigorous current of steam blown in from D. The mixture in C is thus rapidly heated, and the vapour of the organic compound mixed with steam passes over and is condensed in E. For distillations on a small scale it is not necessary to heat C if, however, the flask C contains a large volume of material or material which requires prolonged distillation, it should be heated by a Bunsen burner, otherwise the steady condensation of steam in C will produce too great a volume of liquid. 

If the organic compound which is being steam-distilled is freely soluble in water, an aqueous solution will ultimately collect in the receiver F, and the compound must then be isolated by ether extraction, etc. Alternatively, a water-insoluble compound, if liquid, will form a separate layer in F, or if solid, will probably ciystallise in the aqueous distillate. When steam-distilling a solid product, it is sometimes found that the distilled material crystallises in E, and may tend to choke up the condenser, in such cases, the water should be run out of the condenser for a few minutes until the solid material has melted and been carried by the steam down into the receiver. 

Filter the dried ethereal solution, and then distil off the ether from a small flask, using precisely similar apparatus and the same method as those described in the preparation of aniline (Fig. 64, p. 163 see also Fig. 23(E), p. 45) and observing the same precautions. When the ether has been removed, fit the distilling-flask to a short air-condenser, and distil the benzonitrile, collecting the fraction boiling between 187" and 191°. Yield, 16-5 g. (16 ml.). 

Add 23 g. of powdered (or flake ) sodium hydroxide to a solution of 15 ml. (18 g.) of nitrobenzene in 120 ml. of methanol contained in a 250 ml. short-necked bolt-head flask. Fix a reflux water-condenser to the flask and boil the solution on a water-bath for 3 hours, shaking the product vigorously at intervals to ensure thorough mixing. Then fit a bent delivery-tube to the flask, and reverse the condenser for distillation, as in Fig. 59, p. 100, or Fig. 23(D), p. 45). Place the flask in the boiling water-bath (since methanol will not readily distil when heated on a water-bath) and distil off as much methanol as possible. Then pour the residual product with stirring into about 250 ml. of cold water wash out the flask with water, and then acidify the mixture with hydrochloric acid. The crude azoxybenzene separates as a heavy oil, which when thoroughly stirred soon solidifies, particularly if the mixture is cooled in ice-water. 

Now remove the flask from the water-bath, and slowly add a solution of 5 ml. (5-2 g.) of dry ethyl benzoate in 15 ml. of anhydrous ether down the condenser in small quantities at a time, mixing the contents of the flask thoroughly between each addition. When the boiling of the ether again subsides, return the flask to the water-bath and reheat for a further 15 minutes. Then cool the mixture in ice-water, and carefully pour off the ethereal solution into a mixture of about 60 ml. of dilute sulphuric acid. and 100 g. of crushed ice contained in a flask of about 500 ml. capacity fitted for stearn-distillation, taking care to leave behind any unchanged magnesium. 

During this process some water will have condensed in the steam-trap D and also in the distillation bulb F. If at the end of the steaming-out process, the Bunsen burner is removed from the generator A, the pressure in A will be reduced owing to steam condensation, and the liquid in F will be sucked back into D provided that the benL-over tube is carefully adjusted, the bulb F may be almost completely emptied of liquid as desired. Finally the condensed water in the steam-trap D may be run out by op ing the tap Tj. 

Attention is directed to the fact that ether is highly inflammable and also extremely volatile (b.p. 35°), and great care should be taken that there is no naked flame in the vicinity of the liquid (see Section 11,14). Under no circumstances should ether be distilled over a bare flame, but always from a steam bath or an electrically-heated water bath (Fig.//, 5,1), and with a highly efficient double surface condenser. In the author s laboratory a special lead-covered bench is set aside for distillations with ether and other inflammable solvents. The author s ether still consists of an electrically-heated water bath (Fig. 11, 5, 1), fitted with the usual concentric copper rings two 10-inch double surface condensers (Davies type) are suitably supported on stands with heavy iron bases, and a bent adaptor is fitted to the second condenser furthermost from the water bath. The flask containing the ethereal solution is supported on the water bath, a short fractionating column or a simple bent still head is fitted into the neck of the flask, and the stUl head is connected to the condensers by a cork the recovered ether is collected in a vessel of appropriate size. 

Mix 40 g. (51 ml.) of isopropyl alcohol with 460 g. (310 ml.) of constant boiling point hydrobromic acid in a 500 ml. distilling flask, attach a double surface (or long Liebig) condenser and distil slowly (1-2 drops per second) until about half of the liquid has passed over. Separate the lower alkyl bromide layer (70 g.), and redistil the aqueous layer when a further 7 g. of the crude bromide will be obtained (1). Shake the crude bromide in a separatory funnel successively with an equal volume of concentrated hydrochloric acid (2), water, 5 per cent, sodium bicarbonate solution, and water, and dry with anhydrous calcium chloride. Distil from a 100 ml. flask the isopropyl bromide passes over constantly at 59°. The yield is 66 g. 

Stopper the side arm of a 25 or 50 ml. distilling flask and fit a vertical water condenser into the neck. Place 0-5-1 -0 g. of the dry acid (finely powdered if it is a solid) into the flask, add 2-5-5 0 ml. of redistilled thionyl chloride and reflux gently for 30 minutes it is advisable to place a plug of cotton wool in the top of the condenser to exclude moisture. Rearrange the condenser and distil off the excess of thionyl chloride t (b.p. 78°). The residue in the flask consists of the acid chloride and can be converted into any of the derivatives given below. 

Place 56 g. of clean sodium, cut into small pieces, in a 500 ml. round-bottomed flask fitted with two 25 or 30 cm. double surface condensers in series. Weigh out 136 g. (72 ml.) of freshly distilled allyl iodide, b.p. 99-101° (Section 111,39). Introduce about one quarter of the aUyl iodide through the condensers. Warm the flask gently until the sodium commences to melt and immediately remove the flame. A vigorous reaction sets in and a liquid refluxes in the condensers. Add... 

Place 36 -0 g. of redistilled acetophenone, b.p. 201° (Section IV,136), 300 ml. of diethylene glycol, 30 ml. of 90 per cent, hydrazine hydrate and 40 g. of potassium hydroxide pellets in a 500 ml. Claisen flask provided with a reflux condenser and a thermometer dipping into the liquid (compare Fig. Ill, 31, 1). Warm the mixture on a boiling water bath until most of the potassium hydroxide has dissolved and then reflux (free flame) for one hour. Arrange the apparatus for distillation and distil until the temperature in the liquid rises to 175° (1) keep the distillate (ca. 50 ml.). Replace the reflux condenser in the flask and continue the refluxing for 3 hours. 

Mix intimately in a mortar 100 g. of sodium laevulinate, 250 g. of phosphorus sulphide (1) and 50 g. of clean dry sand. Place the mixture in a flask fitted with a condenser for distillation and a receiver (2). Heat the flask with a free flame until the reaction commences, and then remove the flame. When the reaction subsides, continue the heating until distillation ceases. Wash the distillate with 10 per cent, sodium hydroxide solution to remove acidic by-products and steam distil. Separate the crude 2-methyltliiophene from the steam distillate, dry over anhydrous calcium sulphate, and distil from a little sodium. Collect the pure compound at 113° the yield is 30 g. 

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