Table 104

Boiling point.

•C.

Weight of residue.

Alcohol content.

Weight per cent.

Boiling point.

°C.

Weight of residue.

Alcohol content. Weight per cent.

Boiling point.

°C.

Weight of residue.

Alcohol content.

Weight per cent.

79.1

1000

85.8

81.9

56.6

50.2

86.6

27.6

21.3

79.2

536

83.2

82.1

53.3

48.3

87.1

26.7

19.6

79.4

355

80.7

82.4

50.2

46.3

87.7

24.9

17.9

79.6

-264

78.3

82.6

47.6

44.4

88.3

25.7

16.3

79.7

208

75.9

82.8

45.2

42.5

89.0

24

14.6

79.9

172

73.6

83

431

40.7

89.7

23.2

13

80.1

146

71.3

83.3

411

38.8

90.6

22.3

11.3

80.3

127

69.1

83.5

39.2

37

91.5

21.5

9.7

80.5

111

66.8

83.8

37.6

35.2

92.6

20.7

8.1

80.6

99.3

64.6

84.1

36

33.4

93.9

19.9

6.4

80.8

89.9

62.5

84.4

34.6

31.6

95.2

190

4.8

81

82.0

60.4

84.7

33.3

29.9

96.6

181

3.2

81.2

75.3

58.3

85

32

281

98.2

171

1.6

81.3

69.5

56.2

85.3

30.8

26.4

100

.4-5

0.0

81.5

64.7

54.2

85.7

29.7

24.7

81.7

60.4

52.2

86.2

28.6

23

E. Donitz1 has prepared Table 104, which shows the amount and composition of the distillate and liquid at any point in the course of the distillation of a mixture of alcohol and water. This table is based on Groning's figures for the distillation of alcohol-water mixtures (Fig. 101). It should be noted that the figures given by different experimenters differ to a considerable extent.

By the use of this table the following problems can be solved: 1. The total weight and composition of the original mixture and the composition of the residue being known, to find the amount and composition of the distillate.

Example:Weight of original liquid = 1 kilogram. Composition of original liquid, 50 per cent by volume. Composition of the residue, 10 per cent by volume. 50 per cent by volume =42.5 per cent by weight. 10 per cent by volume =8.1 per cent by weight.

See Table :

From 45.2 kg. at 42.5 per cent remain 20.7 kg. at 8.1 per cent.

From 1 kg. at 42.5 per cent remains 0.458 kg. at 8.1 per cent.

1- .458 =0.542 kg. has been distilled over, and the alcoholic

1 x 42.5-0-458x8-1 strength of the distillate = 0.542 =71-5 per cent by weight.

2. What proportion must be distilled from mixtures of various strengths before the whole of the alcohol is contained in the distillate, and what will be the strength of the distillate?

Example: 1000 kilos, liquid containing 14 per cent by volume of alcohol, 14 per cent by volume = 11.3 per cent by weight. From Table 3 :

22.3 kilos, must be evaporated down to 14.5 kilos. 1000 kilos, must be evaporated down to 650.2 kilos. Thus 349.2 kg. are distilled off. The alcoholic strength of the distillate =32.3 per cent by weight.

3. If the distillate obtained in (2) be redistilled until all the alcohol has passed over, and this process be repeated, what will be the alcoholic content of the successive distillates ? By repeating the calculation explained in (2) for successive distillations it can be found how many distillations are required to raise the concentration of dilute alcohol to any required degree.

A mixture of alcohol and water containing 11.3 percent of alcohol must be distilled five times before the alcohol content of the distillate is-83 per cent by weight.

Strength of 1st distillate, 32.3 per cent by weight.

2nd „ 55 ,,

3rd „ 70.3 ,,

4th „ 78.5 ,,

5th „ 83.0 ,,

1 Maercker-Delbriick, Spiritus-Fabrikation, 1908, p. 694.

These calculations show the results obtained when condensation in the upper part of the still is prevented as far as possible. They are not applicable to stills with rectifying columns.

The distillation of mixtures of ethyl alcohol and water has been dealt with by E. Hausbrand, ReHifizier- und Destillier-Apparate-1916. A theoretical basis is laid down for the proper design of the various parts of the still, and tables are given showing the alcoholic strength of vapour and liquid over any plate in the rectifying and wash columns under various working conditions.1

The Rectifying Column (see Figs. 104,121, 124, 126,127). - The plates of the column should ensure the even distribution of the rising vapour to the liquid on the plate. The vapour rising on to a plate should be completely condensed in the liquid and an entirely fresh lot of vapour evolved. To assist the complete mixing of vapour and liquid on the plate the condensed liquid flowing down from above must be evenly distributed all over the plate. Drops of liquid must not be carried upwards, from one plate to another, by the rising vapour.