The fermenting room has three main requirements for successful commercial distillation. It must allow a uniform temperature to be maintained in the vats; it must have thorough ventilation without any draftiness, and it must be absolutely clean. It should have also plenty of light so that it may be thoroughly inspected. It is true that in the primitive plants all these requisites were violated, but there is no reason for this. The first cost is but little added to by building with these requisites in mind and it is far more profitable in the long run; and it is only by the elimination of the bacteria which are inimical to proper fermentation that the fermenting operation can be performed with any certainty.
For the regulation of the temperature reliance may be had on stoves or heaters, or on special mash heaters and coolers by which the temperature of the mash in the tubs may itself be controlled without reference to the temperature of the fermenting room. When, however, no special and adequate heating means is provided, the walls should be double with an air space between and the doors and windows should either be also double or limited in number.
To ensure good ventilation and plenty of space above the vats wherein to work or install suitable vatting machinery, the walls should be at least twelve feet in height. Outlet openings should be formed around the base of the room leading to the outer air and closed by controllable shutters. These are to allow the escape of the carbonic acid gas evolved during fermentation. These should be most carefully constructed, however, to pervent drafts.
The walls and floor of the fermenting rooms should be so made that they may be easily washed down and kept clean. Concrete floors are excellent for this purpose and the walls also may be faced with concrete or cement covered with a coating composed of a mixture of asphalt and coal tar. This mixture may be also applied to plaster walls with good results.
The fermenting vats, as before stated, are made of wood for small plants, and of iron for larger plants, and are usually from three and a half to four and a half feet in height. After the chief feremnting period, it is necessary that the temperature of the mash be prevented from rising beyond 86°F. and to that end movable cooling tubes, coils and stirrers are used. These consist of parallel frames made up of tubes, preferably of copper, through which cold water is passed and which are moved about in the vat, either vertically or rotativelv. There must be space above the vats, therefore, for the introduction and removal of these cooling frames, and for the gearing whereby they are driven.
As previously stated, mashes to-day are mostly prepared by steaming and disintegrating in a mash cooker of the type shown in Figs. 1 and 41 or in Henze steamers, from which the mash is blown into the preparatory mash vat, where it is stirred and brought to the proper temperature for fermentation. A convenient arrangement of mash cooker, coolers, pump and vats is shown in Fig. 1. Where Henze steamers are used they are arranged in batteries, the blow-off pipes being connected to the preparatory mash vats. These are preferably provided with water cooled stirrers consisting of a frame of straight and vertical tubes mounted on a tubular arm projecting from a tubular shaft, and rotated in a horizontal plane within the closed mash vats, by suitable gears. The rotation of the arm stirs and automatically mixes the mash while cooling it. Another form of cooler is shown diagrammatically in Fig. 4.
Whatever form of cooling apparatus is used, attention should be paid to the ease with which the stirrers or tubes can be kept clean, and to the strength of the apparatus, gears, etc. Concen-
trated or thick mashes require that the stirrers be of massive construction, capable of being rapidly rotated in the liquid.
In preparatory mash vats for use with concentrated mashes, means must also be provided for clearing the mash. These mash cleaners and husk removers usually form part of, or are attached to the vat itself and are driven by gearing from the main shaft carrying power to the mashing room.
A good idea of the general arrangement and correlation of the various apparatus of a plant may be gathered from the sectional view of a grain distillery shown in Fig. 55. It will be seen from this that the mashing apparatus, steamers and mixers are located on the several floors of one building and in such relation to each other that the several operations of saccharifying are carried on in a continuous movement of mash towards the fermenting vats.
Adjoining the fermenting vat room is a section of the plant given up to the manufacture of pure yeast and this and the fermenting rooms are level with the ground, have solid walls whereby a uniform temperature is obtained, and plenty of space for proper ventilation of the vats. A gallery traverses the room about midway the height of the vats so that convenient access may be had to them. The distilling room is high enough to allow for the setting of the various columns, separators and condensers at their proper heights relative to each other, and
FIG. 55.—Continuous Grain Alcohol Distillery— Barbet's System.
Crusher and Sifter.
Measurer containing 1 charge.
Water tank, horizontal saccharifier.
Malt mills, mixers, air pump.
Sterilizer, yeast fermenting vessel.
Vats for continuous fermentation.
Continuous distilling and rectifying columns, refrigerators condensers, etc.
FIG. 55.—Continuous Grain Alcohol Distillery— Barbet's System.
should be so arranged as to its several floors or stages that access to the various pipes and apparatus may be easily had. The steam generator for the column is located in an adjacent room.
In addition to this there should be a malt house for the preparation of malt, located conveniently to the saccharifying building; an engine and boiler room so placed that power may be conveniently transferred to the mixers, stirrers and pumps and to generate steam for the Henze boilers; while adjacent to the distilling building should be the storage tanks and de-naturing department.
Another arrangement of apparatus for a grain distillery with a capacity of 2500 bushels per day is illustrated in Fig. 56. This plant was erected by the Vulcan Copper Works Co., and includes separate stills for gin, alcohol, and rye whiskey, as well as a spirit rectifying column.
The milling and grain mixing departments, the yeast room and the fermenting room are arranged on the several floors of one building in the basement of which is located the vacuum cooker and drop tub and coolers described on page 11 from which the mash is pumped into the fermenting tubs.
The second section of the building contains the distilling apparatus, storage tanks, charcoal rectifiers and spirit rectifying apparatus, while the third section of the building comprises the boiler house and engine room.
In Fig. 57 is shown a view of a small plant for the distillation of beets, the figure giving a good
idea of the arrangement of the diffusion battery in relation to the still and rectifier. The juice from the diffusion battery is pumped into the overhead tanks from which it descends into a dephlegmator and from thence into the still, the vapors from the still passing into the rectifier. The still is a direct, fire-heated still and adjacent to the still is a water heater from which the water passes to the hot water reservoir located above and to one side of the diffusion vats.
A large plant for the distillation of beets is shown in the Section Fig. 58. The beets from the beet silos are carried to suitable washing machines, A, see Chapter VII, in which they are thoroughly cleaned of dirt and gravel. From the washers they are lifted by a conveyor B to a distributor C by which they are conveyed to the cutters or slicers. These consist of horizontal apertured plates revolving at a high speed, and carry knives which plane off slices from the beets. These drop through the apertures of the plate and are conveyed to the diffusion batteries, as by a movable chute D oscillated with a jigging motion through suitable gearing.
The diffusers F should be arranged so that small trucks may be driven beneath them to receive the spent slices and carry them to the spent beet silos. U indicates a gauging tank into which the juice runs from the diffusers. From thence it passes to coolers (not seen) and thence to the fermentation tanks C. R indicates
a small engine for driving the beet slicers and S a battery of pumps whereby the wash may be forced up into the reservoir I from which the wash descends into the still K. H and J are reservoirs for hot and cold water respectively.
From the distilling column K the phlegm or raw spirit passes to the phlegm tank L from which it is drawn as desired into the rectifying column M, thence into the coolers and condensers and thence into the alcohol tanks N.
On the other side of the building as indicated by the chimney is the boiler for generating the motive power for the plant and for supplying the steam necessary for the distilling and rectifying columns and the hot water for the diffusion batteries. The boiler should be very capacious and it would be well to have two, one in reserve.
If possible, advantage should be taken of the natural slope of the ground so that the trucks bringing beets from the silo to the washer and carrying the spent beets away may roll downward by their own weight. The silos for the spent beets should be excavated from the ground and the trucks be constructed to tip their contents into these pits. The natural slope of the bottom of these pits should drain away the water and means be provided whereby carts can load with the spent beets to carry them away.
The spent liquors should flow off into ponds from which they may be drawn away to fertilize land.
A very convenient method of carrying beets from the silos to the washing machine is by means of a narrow canal of rapidly flowing water, flowing between the silos and entering the washing machines. Beets pitched into this stream are carried along by the current to the washers and at the same time undergo a preliminary washing. By laying out a system of channels throughout the beet yard the labor of handling is reduced to a minimum. These channels may be covered by boards on which the beets may be piled. These may be lifted and the beets thereon dumped into the stream.
A plant for the distillation of potatoes would be arranged very much after the plan of the grain distillery heretofore described except that it would have to be provided with apparatus for washing the potatoes and removing stones and adhering clods of earth. These washers, as put on the market, comprise a slotted rotating drum, which tumbles the potatoes about and loosens the dirt. When they escape from the drum they enter a washing trough where they are stirred about by revolving blades and acted upon by a swift current of water. The trough should be about two feet long to properly wash the potatoes. They are then lifted by an elevator to the mouth of the Henze pulpers (see Fig. 2) or the vacuum cookers see Fig. 1).
It is of advantage that the washing apparatus be so located that the potatoes as they are received
may be shoveled into it immediately. The scale for weighing the potatoes as they are brought in should be so located that the manager may attend to the weighing without having to leave the distillery. This and other like details may seem of small moment but it is care in such details which conduces to the success of a plant. As before stated in describing a beet distillery, advantage should be taken of the lay of the land in laying out the plant so that the spent pulp may be easily disposed of, the spent wash carried away, and the finished product conveniently handled.
In Fig. 59, is shown a plant for distilling molasses, designed by the Vulcan Copper Works. before referred to, and erected for the Rio Tamposo Sugar Co., of Tamposo, S. L. P., Mexico.
The molasses as before explained at page 164 being too concentrated, is first pumped into the steam mixing tank on the ground floor of the distilling building. Here it is diluted and heated, mixed with sulphuric acid and pumped into the long ranges of cooling pipes, located along the fermenting room and built on the principle shown in Fig. 4. Here it is further diluted and yeast is added. From the fermenting tubs the molasses beer is pumped into the beer heater and thence into such a still as is shown in Fig. 32.
In addition to this the plant contains a rectifying apparatus for the high wines produced by the beer still, comprising a spirit still, charged from a high wine tank, a rectifying column, separator, and tubular condenser from which the rectified spirit is carried to the storage tanks.
Cane sugar distilleries are practically arranged the same as the molasses distillery above described. The cane is crushed between the rolls of cane crushers on the receiving floor and is then strained to remove the "begasse." The clarified juice is then pumped up to the mixing
tanks. In these the molasses is mixed with spent wash from other fermentations or with water, after which it is acidified and flows to the fermenting vats. The fermenting house should be provided with means for forcing in filtered air and for ventilating, as molasses wash is very sensitive to change in temperature and very liable to become contaminated by injurious ferments. (See Fig.60).
Above each vat should be a cooling coil capable of being lowered into the vat and a water spraying pipe, whereby the mash may be diluted when desired. From the vats, the wash is pumped to the distilling and rectifying columns. In Jamaica the still shown in Fig. 37, is largely used, as also the Coffey still, Fig. 18.
It is very often not profitable to distill spirit from molasses or sugar cane directly at the sugar factories, there being no market on the spot and transportation of the spirit in casks being very costly and difficult, not only because of the lack of transporting means but because the tropical climate tends to warp the empty casks. Transportation of the molasses in casks to a distillery is likewise open to objections of cost and the action of the hot sun in fermenting the molasses and bursting the cask.
Barber has suggested a way out of the difficulty. This consists in boiling the molasses in vacuo, and then running it into molds lined with sheets of paper. These are set by dipping in cold water. When set the loaves wrapped in their paper coverings are as easily handled as sugar loaves. There is no dead weight nor any "empties" to be returned as in the case of casks. The molasses is in a most concentrated form and this makes for economy in freight. There is no risk of deterioration and the loaves may be stored in an ordinary warehouse. This method allows the distillery to be located at centers of transportation or at seaports, while the sugar factories are on the plantation.
Care should be taken in selecting the site for a distillery that an abundance of pure water may be supplied. The purer the water the better, and where water is not pure, purifying apparatus should be provided. The coolness of the water is a factor which must be taken into consideration. The greater amount of water will be used for cooling, and it follows then that the cooler the water the less of it will have to be used.
The horse-power of the engines used in driving the distilling apparatus varies, of course, with the capacity of the still, the average being between 6 H.P. and 30 H.P., for plants having fermenting vats of capacities ranging between two hundred and fifty, and twelve hundred gallons.
It must not be forgotten that the coal consumption of a plant depends upon the economy of heating means in the distilling apparatus, the perfection with which the heat of the vapors is used to heat the wash, the perfection of the boiler grates and the method of firing. These latter matters should be obvious to any distiller, but it is in economy in little things that the successful operation of a plant resides.
Nothing is more surprising than the difference in the coal consumption of different distilleries. Some use a third more than others. This is caused by poor coal, by poor firing, by poor boilers, by hard water, or by poor distilling equipment. With regard to the latter this word of advice may be given: The greater the number of plates in the distilling column, the less the coal consumed per gallon of alcohol produced. It must, however, be taken into account that a large number of plates in a column means a column of considerable height and that in turn means a correspondingly tall still house and increased first cost. Hence it is more economical to use the best forms of traps on the plates and fewer plates, and the best forms of these traps as pointed out in Chapter III, are those wherein the largest quantity of vapor in a finely divided state may come into contact with the greatest number of liquid particles.
In conclusion it may be said that dirt, neglect, carelessness and a too great desire for economy in first cost are all factors in lowering the economical productiveness as well in a distillery as in other manufacturing plants.
Was this article helpful?