« ZurückWeiter »
From the bottom of the Rectifier an inverted syphon pipe (W) communicates with the hot-feints receiver, or the budget as it is called in some distilleries, and the latter through the hot-feints pumps and pipe (H) with the Analyzer.
A line-arm (R) rising from the top of this column passes to a coil of refrigerating pipes in a water tank, for the purpose of condensing any spirituous vapour that may have been driven over the head by an increase in the temperature of the apparatus, either through inattention on the part of the still-man, or by a sudden rush of vapour.
At the lower end, the refrigerating pipe divides into two branches ; one ascending allows the escape of any uncondensed vapour, and also acts as a valve to prevent the still collapsing on being suddenly cooled; the other descending enters either the hot-feints' receiver, or the rectifier, by a syphon pipe. Thus, should any spirit vapour have passed over the head of the still, it is condensed and returned for rectification.
In most stills of modern construction, the spirit pipe, after leaving the spirit sheet, divides into two branches, each fitted with stop-cocks ; one branch (X) leads to the spirit refrigerator, and thence to the close safe and spirit receiver ; the other (Y) to the feints' refrigerator, and on to the feints' receiver. This arrangement prevents any taint from the feints being communicated to the liquid in the spirit refrigerator or spirit pipes.
A small sampling apparatus (2) consisting of a rectangular vessel, about three feet in length, by eight or nine inches in breadth, and containing three small coils of refrigerating pipes, is attached to the side of the rectifier, nearly on a level with the spirit sheet : the coils are connected respectively with the spirit pipe (by M), the low-wines line-arm (by L), and with the bottom frame of the Analyzer (by K); the coils terminate at the other end in glass cups, containing coloured glass beads calculated to float at different specific gravities. When at work, these cups are kept constantly filled by a fine stream of liquor entering at the bottom and overflowing at the top, where it is collected from the three cups, and conveyed below to the hot-feints receiver.
It is principally by means of the tempering pipe (U) and the small glass beads, that the attendant regulates the working of the still. The beads in the spirit cup indicate the gravity or strength of the spirit which is collected on the spirit sheet, or is then flowing to the spirit-receiver ; those in the low-wines cup show the strength of the low wines passing into the rectifier; while the beads in the third cup enable the attendant to judge whether the wash leaving the Analyzer, is thoroughly exhausted of its spirit.
The valves (D”) fixed in the diaphragms in both columns, are intended to allow the passage of steam or vapour, should the perforations in the diaphragms become clogged; or to act as safety valves should the pressure of the steam or vapour be too great for the plates. The slip joints on the line-arms are for a similar purpose. These valves and loose joints could not safely be dispensed with as the elastic force of alcohol vapour is very great ; one tolume of alcohol will yield 488 volumes of vapour at 2120 Fah. ; while compared with water at the same temperature, the volume of alcoholic vapour is greater in the ratio of 3.14 to 1•00. The syphon pipes employed are either in the form of an inverted syphon or U shaped tube, or of the two forms combined, and are intended to prevent any steam or vapour forcing its way through the pipe with the wash or feints.
Although the Rectifier is furnished with a spirit sheet, and the spirit is allowed to make its exit from the front of the column, it will be seen from the construction
of the apparatus that this is not a matter of necessity, but an arrangement for the purpose of obtaining spirit of a very high strength and purity. Where only whiskey of the ordinary strength and flavour is required, the spirit sheet may be dispensed with, and the spirit vapour passed at a higher temperature over the head of the column by the vapour pipe to the refrigerator ; this spirit not being so highly rectified, will contain a much larger amount of essential oil, &c., and thus more nearly resemble common still whiskey than the patent still spirit, when reduced to the ordinary strength.
Coffey's still as thus constructed, is capable of distilling per hour from 2000 to 5000 gallons of wash of the original gravity of fifty degrees, and of producing a highly rectified and neutral spirit at one distillation, with a remarkable saving of fuel; it is stated that it will save nearly three-fourths the amount of fuel that would be consumed in distilling an equal quantity of wash by the common still.
Principle of Action—The action of this still depends upon the difference between the boiling points of absolute alcohol and water, and upon the separation of the alcohol from the watery portion of the wash when in a state of vapour at a few degrees above the boiling point of alcohol.
If the mixed vapours of alcohol and water be passed through a good condensing medium, the temperature of which is lower than the boiling point of water but not so low as that at which alcohol boils, the water will be condensed while the alcohol will retain its vaporous form. Or, when the mixed vapours are successively passed through compartments maintained at temperatures vary. ing from 2000 to 174°, the watery vapour becomes separated from the alcoholic and is condensed, the alcoholic alone passing off, while the low temperature of the wash—from 80° to 90° when it enters the Rectifier-presents such facility for maintaining the compartments at the necessary temperatures, that the separation of the alcohol can be accomplished with great despatch.
Thus it will have been seen, that to effect the separation of the alcohol, the wash must first be brought to the boiling point, by which alcoholic or spirituous vapour will be given off, mixed with a large amount of the vapour of water, and essential oil; and that this mixed vapour must then be subjected to a constantly decreasing temperature, so as to separate, as far as possible, the spirituous from the impure watery portions, by condensing the latter; and, lastly, that the spirituous vapour must be subjected to a still lower temperature, to ensure the separation of the alcohol, now nearly pure, from the remaining feints, or compound of spirit and fusel oil.
On referring to the account of the construction of the rectifying column, it will be perceived, that the serpentine pipe for conveying wash from the reservoir to the Analyzer, traverses the space in each frame, from back to front, four times; the wash passing through this pipe, being at a low temperature, serves as a refrigerant to the mixed spirituous vapour occupying the several compartments. This mixed vapour having been conducted by the line-arms from the Analyzer to the bottom frame of the Rectifier, ascends through the column, while the cold wash entering the pipes near the top of the column flows down, meeting and cooling the ascending vapour, and is itself, by the time it reaches the bottom of the Rectifier, brought to a high temperature, by means of the heat it has abstracted from the low-wines vapour.
reat an extent does the wash become heated in this manner, that when it enters the Analyzer it is very near the boiling point.