Heat simple distillation

Heat Integration of Sequences of Simple Distillation Columns... 

Unless there are constraints severely restricting heat integration, sequencing of simple distillation columns can be carried out in two steps (1) identify the best few nonintegrated sequences and (2) study... 

Andrecovich, M. J., and Westerberg, A. W., A Simple S3mthesis Method Based on Utility Bounding for Heat-Integrated Distillation Sequences, A/CAE 7, 31(3) 363, 1985. 

It must be borne in mind that in spite of the fact that the solvents have normal boiling points below 90-95°, they cannot always be completely removed by heating on a steam or water bath when they form part of mixtures with less-volatile liquids. Simple distillation may lead to mixtures with higher boiling points than the individual solvents, so that separation of the latter may not be quite complete. In such cases the distillation should be completed with the aid of an air bath (Fig. 77,5,3) or an oil bath the Are hazard is considerably reduced since most of the solvent will have been removed. 

Setup for simple distillation, on the water bath, or if you don t wish to recover the alcohol (shame on you) just heat gently with a... 

The pressure used in producing gas wells often ranges from 690— 10,300 kPa (100—1500 psi). The temperature of the inlet gas is reduced by heat-exchange cooling with the gas after the expansion. As a result of the cooling, a liquid phase of natural gas liquids that contains some of the LPG components is formed. The liquid is passed to a set of simple distillation columns in which the most volatile components are removed overhead and the residue is natural gasoline. The gas phase from the condensate flash tank is compressed and recycled to the gas producing formation. 

To the cooled reaction mixture, 200 ml. of water is added carefully with stirring. Potassium carbonate is added with continued stirring until the water layer is saturated the mixture is now transferred to a separatory funnel and extracted three times with 60-ml. portions of ether. The combined ether extracts are dried over solid sodium hydroxide and are then transferred to a simple distillation apparatus. Distillation is commenced with a steam bath as source of heat when most of the ether has been removed, the steam bath is replaced by a flame. Distillation is continued until most of the piperidine (b.p. 106°) has been removed. The cooled residue in the distillation flask is recrystallized from petroleum ether (boiling range 30-60°) with the use of charcoal. There is obtained 30.0 g. (71%) of N-/3-naphthyl-piperidine as tan crystals, m.p. 52-56°. An additional recrystallization from the same solvent gives crystals, m.p. 56-58°, with about 10% loss in weight (Note 6). 

Consider now the consequences of placing simple distillation columns (i.e. one feed, two products, one reboiler and one condenser) in different locations relative to the heat recovery pinch. The separator takes heat Qreb into the reboiler at temperature Treb and rejects heat Qcond at a lower temperature Tcond There are two possible ways in which the column can be heat integrated with the rest of the process. The reboiler and condenser can be integrated either across, or not across, the heat recovery pinch. 

Evolving the Design of Simple Distillation Columns to Improve Heat Integration 447... 

SIMPLE DISTILLATION COLUMNS TO IMPROVE HEAT INTEGRATION... 

Figure 21.8 Heat integration of a sequence of two simple distillation columns. (From Smith R and Linnhoff B, 1988, Trans IChemE, CHERD, 66 195, reproduced by permission of the Institution of Chemical Engineers.)...

A simple steam-distillation apparatus such as that given by Fieser 3 4 is entirely satisfactory. It is usually necessary to heat the distillation flask with a steam bath or a small flame in order to minimize the accumulation of excess water in the flask. 

Diisopropylamine is purified by heating to reflux over sodium hydroxide (NaOH) for 3-12 hr, followed by simple distillation from NaOH. 

A 1-1. steel bomb is charged with 200 g. (1.51 moles) of dicyclo-pentadiene (Note 1). The bomb is flushed with ethylene (Note 2) and then filled while shaking to an initial pressure of 800-900 p.s.i. at 25°. Shaking is continued as the bomb is slowly heated (Note 3) to 190-200° and maintained at this temperature for 7 hours (Note 4). At the end of this period, the reaction vessel is cooled and vented, and the crude product is transferred into a simple distillation apparatus (Note 5). A fraction boiling between 93° and 100° is collected, yield 162-202 g. (57-71%, based on dicyclopentadiene) (Note 6). The norbornylene may be redistilled with negligible losses to give a final product, b.p. 94-97°/740 mm., m.p. 44-44.5° (sealed capillary). 

Cyclopentanecarboxyaldehyde may trimerize if heating is prolonged hence a fast, simple distillation is done. When the distillation residue is cooled, a solid may appear. This solid can be distilled above 78° (100 mm.) as a clear liquid which solidifies when allowed to stand. Recrystallization of this material from 95% ethanol gives a white solid melting at 122-124°. This product was shown to be cyclopentanecarboxaldehyde trimer by... 

Fearing little, you set up a Class 1 Simple Distillation and begin to heat the mix. If you kept track of the temperature of the liquid (and you don t the... 

A. AcetamidoaceUme. A mixture of 75.0 g. (l.O mole) of glycine (Note 1), 475 g. (485 ml., 6 moles) of pyridine (Note 1), and 1190 g. (1.1 1., 11.67 moles) of acetic anhydride (Notes 1 and 2) is heated under reflux with stirring for 6 hours (Note 3) in a 3-1., three-necked, round-bottomed flask. The reflux condenser is replaced by one set for downward distillation, and the excess pjnidine, acetic anhydride, and acetic acid are removed by distillation under reduced pressure. The residue is transferred to a simple distillation apparatus such as a Claisen flask and is distilled to give 80-90 g. (70-78%) of a pale yellow oil, b.p. 120-125° (1 mm.). This product is of satisfactory purity for use in step B. 

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