Spiral still-head

Spiral Still-Head.—The efficiency is further improyed by bending the sloping portion of the tube into the form of a spiral, probably because a better admixture of the vapour is thus produced by this device the amount of liquid in the still-head is still further reduced. 

Warren s Still-Head.—The employment of an elongated spiral still-head, kept at a constant or slowly rising temperature, was first recommended by Warren (1). The spiral tube was heated in a bath of water or oil its length varied from to lO feet and its internal diameter from to inch. 

When a regulated temperature still-head is employed, it is better, for two reasons, to bend the tube into the form of a spiral in the first place, the effective length of the still-head may be thereby greatly increased without unduly adding to the height of the bath, and in the second place, as has been already pointed out, the spiral form is more efficient than the vertical. 

The dried malted barley is ground and mashed in a tub, after which the Hquid portion is drained off, cooled, and placed in the fermentor. After fermentation, a batch distillation system is usually used to separate the whisky from the fermented wort. The stiU consists of a copper ketde with a spiral tube or "worm" leading from the top. The dimensions and shape of the stills have a critical effect on the character of the whisky. The product taken off in the first part of the distillation is called foreshots (heads). The middle portion is the high wines and the last portion is the feints (tails). The middle portion is redistilled at the 140—160° proof (70—80%) range and matured in used oak cooperage. 

Vat stills consist of cylindrical wooden vessels built of staves strongly hooped with wrought iron. They have high copper domes covering openings in the heads of the vessels which communicate with a retort or retorts of the Jamaica pattern, but, as a rule, the retort acts as the lowest vessel of a rectifying column. As in Winter s still a spiral pipe or a series of... 

Microscale spinning-band distillation apparatus (Fig. 5.11) can achieve nearly 12 theoretical plates and are simple enough to be used in the instructional laboratory. This stiU has a Teflon band that fits closely inside an insulated glass tube. The Teflon band has spiral grooves which, when the band is spun (1000-1500 rpm), rapidly return condensed vapor to the distillation pot. A powerful extension of this apparatus uses a short spinning band inside a modified Hickman stiU head (see Fig. 3.15). These stills are called Hickman-Hinkle stills 4-cm Hickman-Hinkle columns can have more than 10 theoretical plates. The commercially available 2.5-cm version is rated at 6 theoretical plates. Experiments [3C] and [3D] involve fractional distillation with spinning-band columns. 

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