Dorn’s Compound StillFig.12.—Dorn’s Compound Still.
Fig.12.—Dorn’s Compound Still.
The principle of compound distillation is well shown in Dorn’s apparatus, Fig.12. This consistsof a still or boilerAhaving a large dome-shaped head, on the interior faces of which the alcoholic vapors will condense. Thus only enriched vapors will pass up through goose-neckBto the mash heaterD.Cis a worm the end of which passes out to a compartmentEthrough an inclined partitionF. From the compartmentEa pipeeleads into the stillA. An agitatorHis used for stirring the mash, so that it may be uniformly heated. A pipedprovided with a cock allows the mash to be drawn off into the stillA. From the highest point of the compartmentEa pipeMleads to condensing coilKin a tubJof cold water, having a draw-off cockI.
At the exit end of the condensing wormKthe tube is bent in a U form as atL, one arm of which has a curved open-ended continuationn, through which the air in the worm is expelled. The other arm opens into an inverted jarlcontaining a hydrometer, for indicating the strength of the spirit. The spirits pass off throughminto a receiver.
In operation the mash is admitted into the heaterDthroughGuntil the heating tank is nearly filled. A certain amount of mash is then allowed to run into the stillAthrough the piped. The cock indis closed and the fire lighted.
The vapors from the still are condensed in wormCand the condensed liquid drops down into compartmentE. Any vapor passing throughBandCso highly heated as to be uncondensed incoilsCpasses through the layer of liquid in compartmentE, collects in the highest portion of the compartment and passes through pipeMto coilKwhere it is entirely liquefied. If the liquid inErises beyond a certain level it passes through pipeeback to the still. Any vapors which may collect in the upper part ofDpass into the small bent pipe opening into the first coil of wormC. Water for rinsing the heaterDmay be drawn through cocksfrom the tubJand warm water for rinsing the still, through pipedfrom the heater.
Another form of compound still is shown in Fig.13. In this the stillSis divided into an upper and lower compartment by a concavo-convex partitiond, having at its crown an upwardly extending tubetfrom which projects side tubesp. A pipePopens above and extends from tubet.Cis the mash heater and condenser. Connected to the head of the still is a pipeTthrough which the vapors pass to a condensing coilfformed on the wall of the heaterC. At its bottom the coilfextends out of the heater, through the water tubWand out to receiver as atF. In the heat of this heater is a valveVwhereby any vapors which may arise from the heated mash are conducted by pipeUtoT.
The heaterCis filled through funnelYand the mash is admitted to the still through pipebhaving cocka. The pipePextends to the upper part of the water tubWand then downward to the bottom, where it again enters the still.
An opening in the partitiondis controlled by a valveGwhich allows liquid in the upper compartment of the still to flow into the lower. Spent mash may be drawn off throughcand the height of the water in tubWbe regulated by pipeZ.
Compound StillFig.13.—Compound Still.
Fig.13.—Compound Still.
The operation of this still is similar to Dorn’s still. Mash is put intoCand a quantity of it is let into the upper compartment of the still and into the lower compartment by valveG. This valve is closed and the fire started. The vapors pass upwardthrought. If they are quite highly vaporized they pass onward upP, are condensed in their passage through the cool water tub and return as liquid to the upper compartment where they are further heated.
The liquid in the upper compartment is thus constantly enriched and the vapor therefrom passes out through pipeTinto condensing coilsfwhere it is condensed into spirit and passes off byF.
Compound Direct Fire StillFig.14.—Compound Direct Fire Still.
Fig.14.—Compound Direct Fire Still.
The funnel tubeYacts also as a means of warning the attendant as to the condition of the mash. If it is too high in level and the pressure of vapor in the heaterCtoo great, liquid will be forced out ofY; if on the contrary, the mash sinks belowthe level of the pipe then vapor will escape and the heater needs refilling.
Fig.14shows a simple form of compound direct fire still as manufactured by the Geo. L. Squier Mfg. Co., of Buffalo, N. Y.
Cellier-Blumenthal carrying this principle further devised an apparatus which has become the basis of all subsequent improvements; indeed, every successive invention has differed from this arrangement merely in detail, the general principles being in every case the same. The chief defect in the simple stills was that they were intermittent that is required the operations to be suspended when they were recharged, while that of Cellier-Blumenthal is continuous; that is to say, the liquid for distillation is introduced at one end of the arrangement, and the alcoholic products are received continuously, and of a constant degree of concentration, at the other. The saving of time and fuel resulting from the use of his still is enormous. In the case of the simple stills, the fuel consumed amounted to a weight nearly three times that of the spirit yielded by it; whereas, the Cellier-Blumenthal apparatus reduces the amount to one-quarter of the weight of alcohol produced. Fig.15shows the whole arrangement, and Figs.16to17represent different parts of it in detail.
Cellier-Blumenthal StillFig.15.—Cellier-Blumenthal Still.
Fig.15.—Cellier-Blumenthal Still.
In Fig.15Ais a boiler, placed over a brick furnace;Bis the still, placed beside it, on a slightly higher level and heated by the furnace fluewhich passes underneath it. A pipeeconducts the steam from the boiler to the bottom of the still. By another piped, which is furnished with a stop cock and which reaches to the bottom of the stillA, the alcoholic liquors in the still may be run from it into the boiler; by turning the valve the spent liquor may be run out ata. The glass tubesbandfshow the height of liquid in the two vessels.Kis the valve for filling the boiler andcthe safety valve.
Details of Rectifier ColumnFig.16.—Details of Rectifier Column.
Fig.16.—Details of Rectifier Column.
The still is surmounted by a columnC, shown in section in Fig.16. This column contains an enriching arrangement whereby the liquid flowing downinto the stillBis brought into intimate contact with the steam rising from the still. The liquid meets with obstacles in falling and falls downward in a shower, which thus presents multiplied obstacles to the ascent of the vapor. The liquid is thus heated almost to the boiling point before it falls into the stillB. The construction for effecting this is shown atC, Fig.16and consists of an enclosed series of nine sets of circular copper saucer-shaped capsules, placed one above the other, and secured to three metallic rods passing through the series so that they can be all removed as one piece. These capsules are of different diameters, the larger ones which are, nearly the diameter of the column, are placed with the rounded side downwards, and are pierced with small holes; the smaller ones are turned bottom upwards, a stream of the liquid to be distilled flows down the pipehfromE, into the top capsule ofCand then percolating through the small holes, falls into the smaller capsule beneath, and from the rim of this upon the one next below, and so throughout the whole of the series until it reaches the bottom and falls into the stillB. The vapors rise up into the column from the still and meeting the stream of liquid convert it partially into vapor which passes out at the top ofCconsiderably enriched, into the columnD.
Fig.16shows a sectional view of the columnD, the “rectifying column” as it is called. It contains six vessels, placed one above the other,in an inverted position, so as to form seals. These are so disposed that the vapors must pass through a thin layer of liquor in each vessel. Some of the vapor is thus condensed and the condensed liquid flows back into columnC, the uncondensed vapor considerably enriched passing up the pipeJ, into the coilSin the condenserE, Fig.17, which is filled with the “wash” to be distilled.
Details of Condenser and Mash HeaterFig.17.—Details of Condenser and Mash Heater.
Fig.17.—Details of Condenser and Mash Heater.
Entering by the pipet, Fig.15, the undistilled liquid or “wash” is distributed over a perforated platey y, and falls in drops into the condenserE, where it is heated by contact with the coilScontaining the heated vapors. The condenser is divided into two compartments by a diaphragmXwhich is pierced with holes at its lower extremity;through these holes the wash flows into the second compartment, and passes out at the top, where it runs through the pipeh, into the top of the columnC.
The vapors are made to traverse the coilS, which is kept at an average temperature of 122° F., in the right hand compartment, and somewhat higher in the other. They pass first throughJinto the hottest part of the coil, and there give up much of the water with which they are mixed, and the process of concentration continues as they pass through the coil. Each spiral is connected at the bottom with a vertical pipe by which the condensed liquors are run off; these are conducted into the retrograding pipep p. Those which are condensed in the hottest part of the coil, and are consequently the weakest, are led by the pipeLinto the third vessel in the columnD, Fig.16, while the stronger or more vaporized portions pass throughL′into the fifth vessel. Stop-cocks atm,n,oregulate the flow of the liquid into these vessels, and consequently also the strength of the spirit obtained.
Lastly, as the highly concentrated vapors leave the coilSatR, they are condensed in the vesselF, which contains another coil. This is kept cool by a stream of liquid flowing from the reservoirHinto the smaller cisternGfrom which a continuous and regular flow is kept up through the tapvinto a funnelNand thence into condenserF. It ultimately flows into condenserEthrough pipet, there being no other outlet. Thefinished products run out by pipexinto suitable receivers.
It will be seen that the condenserEhas two functions. First it condenses the alcoholic vapors before transmitting them to the final condenserF, rejecting and sending back those vapors which are not highly enough vaporized. Second it heats the wash intended for distilling by appropriating the heat of the vapors to be condensed. Thus two birds are killed with one stone. It will be noticed that the same result is accomplished in the columnsCandD. This is the principle of all modern stills.
Another form of still which is very analogous to that last described is Coffey’s apparatus, shown in Fig.18, and is the immediate prototype of the stills used to-day in all but the simplest plants.
Coffey’s Rectifying StillFig.18.—Coffey’s Rectifying Still.
Fig.18.—Coffey’s Rectifying Still.
It consists of two columns,Cthe analyser, andHthe rectifier, placed side by side and above a chamber containing a steam pipebfrom a boilerA. This chamber is divided into two compartments by a horizontal partitionapierced with small holes and furnished with four safety valvese e e e. The columnCis divided into twelve small compartments, by means of horizontal partitions of copper, also pierced with holes and each provided with two little valvesf. The spirituous vapors passing up this column are led by a pipeito the bottom of the second column orrectifier. This column is also divided into compartments in precisely the same way, except that there arefifteen of them, the ten lowest being separated by the partitions, which are pierced with holes. The remaining five partitions are not perforated, but have a wide opening as atw, for the passage of the vapors, and form a condenser for the finished spirit. Between each of these partitions passes one bend of a long zig-zag pipem, beginning at the top of the column, winding downwards to the bottom, and finally passing upwards again to the top of the other column, so as to discharge its contents into the highest compartment. The apparatus works in the following way: The pumpQis set in motion, and the zig-zag pipemthen fills with the wash or fermented liquor until it runs over atninto the highest compartment of columnC. The pump is then stopped, and steam is introduced throughb, passing up through the two bottom chambers and the short pipeFinto the analyzing column, finally reaching the bottom of the other column by means of the pipei. Here it surrounds the coil pipemcontaining the wash, so that the latter becomes rapidly heated.
When several bends of the pipe have become heated, the pump is again set to work, and the hot wash is driven rapidly through the coil and into the analyzer atn. Here it takes the course indicated by the arrows, running down from chamber to chamber through the tubeshuntil it reaches the bottom; none of the liquor finds its way through the perforations in the various partitions, owing to the pressure of the ascending steam.
As the liquid cannot pass through the holes in the partitions it can only pass downward through the drop-pipe tubesh. By this means the mash is spread in a thin stratum over each partition to the depth of the sealgand is fully exposed to the steam forcing its way up through the holes, the alcohol it contains being thus volatilized at every step.
In its course downwards the wash is met by the steam passing up through the perforations, and the whole of the spirit which it contains is thus converted into vapor. As soon as the chamberBis nearly full of the spent wash, its contents are run off into the lower compartment by opening a valve in the pipeV. By means of the cockE, they are finally discharged from the apparatus. This process is continued until all the wash has been pumped through.
The course taken by the steam will be readily understood by a glance at the figure. When it has passed through each of the chambers of the analyzer, the mixed vapors of water and spirit pass through the pipeiinto the rectifying column. Ascending again, they heat the coiled pipem, and are partially deprived of aqueous vapors by condensation. Being thus gradually concentrated, by the time they reach the opening atwthey consist of nearly pure spirit, and are then condensed by the cool liquid in the pipe, fall upon the partition and are carried away by the pipeyto a refrigeratorW. Any uncondensed gases pass outby the pipeRto the same refrigerator, where they are deprived of any alcohol they may contain. The weak liquor condensed in the different compartments of the rectifier descends in the same manner as the wash descends in the other column; as it always contains a little spirit, it is conveyed by means of the pipeSto the vesselLin order to be pumped once more through the apparatus.
The condensed spiritgathered over the platesvpasses out through the pipeyto the condensing wormT. If any vapors escape the condensing plates they pass intoRand are condensed in the wormTalso. From wormTthe spirit flows into a suitable receiverZ.
Before the process of distillation commences, it is usual, especially when the common Scotch stills are employed, to add about one lb. of soap to the contents of the still for every 100 gallons of wash. This is done in order to prevent the liquid from boiling over, which object is effected in the following way: The fermented wash always contains small quantities of acetic acid; this acts upon the soap, liberating an oily compound which floats upon the surface. The bubbles of gas as they rise from the body of the liquid are broken by this layer of oil, and hence the violence of the ebullition is considerably checked. Butter is sometimes employed for the same purpose.
Rotary Current StillFig.19.—Rotary Current Still.
Fig.19.—Rotary Current Still.
Figs.19and20show a diagrammatic section and a plan of a still used for thick mashes which areliable to burn. This comprises a circular chamberBsupported over suitable heating means, having on its bottom a series of concentric partitionsbwhich divide the bottom of the chamber into shallow channels for the mash. Running diametrically through the chamber is a partition.
Rotary Current StillFig.20.—Rotary Current Still.
Fig.20.—Rotary Current Still.
Indicator for Regulating the Distilling FireFig.21.—Indicator for Regulating the Distilling Fire.
Fig.21.—Indicator for Regulating the Distilling Fire.
The mash passes from a tank asAby a passageato an opening on one side of the central portion and into the outside channelb. The current of liquid passes along the outer channel until it is deflected by the central partition into the next interior channelband so on until it arrives at the center when it passes through the central partition into the other half of the chamber. Here it passes around back and forth and gradually outward to the outermost channel from which it passes off through an adjustable gate in outletc. By adjusting this gate, and a gate or cock in inlet passagea, the passage and consequent depth ofthe liquid in the channels may be regulated. The vapor rising from the mash is carried over to a condenser through pipeD. In order to keep the mash from burning a chaingis rotarily reciprocated along the channels by means of the barG, the gearEand the crank shafte. Various modifications of this construction have been devised. The advantage of the still lies in submitting the mash in a thin current to the action of the heat, and the consequent rapid vaporization.
Every distillation consists of two operations: The conversion of liquid into vapor, and the reconversion of the vapor into liquid. Hence perfect equilibrium should be established between the vaporizing heat and the condensing cold. The quantity of vapor must not be greater or less than can be condensed. If fire is too violent the vapors will pass out of the worm uncondensed. Ifthe fire is too low the pressure of the vapor is not great enough to prevent the entrance of air, which obstructs distillation. As a means of indicating the proper regulation of the fire, the simple little device shown in Fig.21may be used.
This consists of a tube of copper or glass having a ballBeight inches in diameter. The upper endEof the tube is attached to the condensing worm. The lower end of the tube is bent in U-shape; the length of the two bends frombto outlet is four feet. The ball has a capacity slightly greater than the two legs of the bend.
Normally the liquid in the two legs will stand at a level. If, however, the fire is too brisk the vapor will enter the tube and drive out the liquor atd, and thus the level in the legCwill be less than in the legD. If, however, the fire is low, the pressure of vapor in the worm will decrease and the pressure of the outside air will force down the liquid in legDand up legCinto the ball.
A more perfected device but operating on the same principle is shown in Fig.26.
It is obviously impossible to present in the small compass of this book a description of all the varieties of stills used, but these which have been described illustrate the principles on which all stills are constructed and were chosen for their simplicity of construction and clearness of their operation. The principle of their operation is exactly the same as the more modern forms now to be described.
In the previous chapter we have given a description of small, simple stills, such as were used until late years, and which are yet used in many localities where distilling is carried on on a small scale. We will now describe the principle features of more complicated and elaborate apparatus.
All modern distilling apparatus for the production of a high grade of alcohol is based upon the principle set forth in the description of the Coffey still; that is, upon using a distilling column and a concentrating column, wherein the “wash” or mash fermented as described, passes over a series of plates or other obstructions in contact with an ascending column of heated vapor. This heated vapor extracts the alcohol from the wash, or from the low wines of the concentrator, and is continually strengthened during its journey until it passes off to a condenser as a vapor very rich in alcohol. The converse of this is true with the wash, which in its downward course is gradually deprived of its alcohol until it finally passes off at the bottom of the column.
Diagramatic View of Column Still and Accessory ApparatusFig.22.—Diagramatic View of Column Still and Accessory Apparatus.
Fig.22.—Diagramatic View of Column Still and Accessory Apparatus.
Fig.22is illustrative of the general form andarrangement of such a column and its adjuncts; the details, however, will vary with each make of still. In this the “column” consists of a casing really continuous but divided into two portions—the distilling portionAand the rectifying portionB. The operation is alike, however, in principle in both portions.
Distilling PlateFig.23.—Distilling Plate.
Fig.23.—Distilling Plate.
The wash by means of a suitable pump is forced into an overhead tank or concentratorGwhere it is warmed by the hot vapors as will be later described.It passes around the interior of the concentrator in a coilcand then passes off by a pipeato the uppermost plate of the distilling portionAof the column.
The plates, as before explained on page55, are each formed with a dropping tubeO(see Fig.23), which extends above the plate to an extent slightly less than the desired thickness of the layer of liquid on each plate, and with perforations each having an upwardly projecting rim, and each covered with a capA. This rim and cap form a trap. The ascending vapors pass up through the perforations, down between the rim and the edge of the cap and thus out through the layer of wash contained on the cap. The wash remains constantly level with the top of the tubeO, the excess running off through the tubeOto the compartment or plate beneath.
To return to Fig.22, the wash by the pipeaenters the distilling portion of the column at the uppermost plate thereof and, as described above, drops down from plate to plate. A steam pipeSenters the bottom compartment of the distilling portion of the column and the steam as it rises through the little traps, bubbles out through the layer of wash and in each compartment enriches itself with alcohol. Thus the rising column of vapor is constantly becoming richer and the downward current of wash constantly weaker until at last it passes away as spent wash at the very bottom of the column by the pipeD.
The hot vapors, as before described, pass upward and enter the rectifying portion of the columnB. This consists of a series of compartments having perforated bottoms and dropping tubes. The vapor passes upward through these perforations of the plates,—the condensed portion of it dropping back again on to the lower plates or on to the distilling plates to be again vaporized and concentrated and the more highly vaporized portion passing out at the top of the column through the pipeEto the concentratorG.
The concentrator consists of a tank containing water within which is supported a vesselFhaving double walls. The interior of this vessel is likewise filled with water. Between the double walls and surrounding the coiled pipecpasses the vapors from pipeE.
At the bottom of the vesselFis a compartmentfconnected by a pipeF′with the upper compartment of the rectifying column. The less highly heated vapors will be condensed by the passage through the double walls of the vessel and the condensation will collect in the compartmentf, and from there pass off by pipeF′back to the rectifying column, to be again vaporized and strengthened by the descent from plate to plate ofB.
The rich and highly vaporized vapors which have passed the test of this preliminary concentration, pass out of the compartmentfby a pipeM. Here again the water surrounding the pipe tends tocondense all but the most highly charged vapor and send it back to compartmentfbut the vapor which succeeds in passing over through pipeGis carried downward to a condenserHwhere it is finally condensed and drawn off as atg. It is necessary that the rate of mash feed be regulated so that neither too much mash shall be pumped into the mash heaterG, or too little, and the pipe leading from the pump to the heater is therefore provided with a tap and an indicating dial.
In these modern stills the following are particularly important points to be especially brought to the consideration of the distiller.
It cannot be too strongly impressed that effectiveness of the distilling column depends on the plates dividing it,—that is, upon the horizontality of the plates and the form of the traps or perforations. If the plates are not horizontal the wash is not maintained at a uniform level across the entire extent of the plate and hence some of the ascending vapor will pass out without contacting with the wash through uncovered traps, while others of the traps will be so deeply submerged in wash that the vapor cannot bubble through.
Again the caps should be so made as to divide the vapor into fine streams and bring it into contact with each part of the wash. Plates simply perforated and uncapped give excellent results for they molecularize the vapor ascending through the liquid contained on the plates, but they require a constant pressure of vapor, and any variations ofpressure tends to discharge them. In addition these perforations gradually enlarge by the action of acids in the wash or clog up, and the apparatus soon works badly.
Good forms of capped traps are those shown in Figs.24,25devised by Barbet. These are provided with an interior upwardly projecting rim. Extending over the rim and down around it is a copper cap having its margin slitted.
The wash carried on the plate circulates about the caps and the alcoholic vapors bubble out through the slits and up through the wash, the vapor thus being finely divided and coming into intimate contact with each portion of the wash and thus more thoroughly depriving it of its alcohol.
Barbet TrapFig.24.—Barbet Trap.Fig.25.—Barbet Trap.
Fig.24.—Barbet Trap.Fig.25.—Barbet Trap.
Besides this there is another advantage resident in these caps, namely, that distillation may be stopped for several hours and then re-started without trouble for the reason that the wash has been retained on the plates, whereas were the plates simply perforated the wash would ooze through and the plates have to be recharged. Thisform of plate may be easily repaired and does not necessitate the removal or replacement of the plate itself. The caps alone need be removed.
For thick washes, which tends to obstruct the slits of the cap, Barbet has devised the cap shown at the right in Fig.25. This cap extends down to the plate itself, and has very narrow slits in its periphery. With such a cap as shown in Fig.24, the bran, sediments, etc., would tend to settle upon the top of the cap, enter beneath it and through the slits. The cone-shape of the top of this cap prevents the deposit of dregs thereon and the very narrow slits oppose the entrance of bran or sediment.
While, for the sake of clearness, an old form of concentrator,G, has been shown, the concentrator, preheater for the wash, and condensers, to-day, are usually composed of bundles of tubes through which the vapors pass surrounded by water or the cool wash. These should be of bronze or copper and made without solder. The tubes should be capable of being taken out for cleaning or repairing.
In many distilling apparatuses the distilling column and the rectifying column are in two parts, one beside the other. This overcomes the objection of having a very high column and also prevents the low wines,i.e., the weak alcoholic liquor after its first concentration, from passing into the wash as it would do with the continuous column.
Steam RegulatorFig.26.—Steam Regulator.
Fig.26.—Steam Regulator.
In order that the amount of steam entering the column may be regulated, the column is usually provided with a steam regulator (Fig.26); whoseprinciple of operation may be easily under stood by referring to Fig.22. It comprises an upper and a lower chamberZ Z′connected by a central tubeKwhich projects down nearly to the bottom of the lower chamber. A pipeWcommunicates with the steam chamberRof the column and enters the chamberZabove the level of the water contained therein. In the upper chamberZ′, is a floatX, connected to the differential leverTof a steam valveT′which controls the inlet of steam passing through pipeSto the steam chestR. The principle of operation is very simple. When the pressure in the steam chestRbecomes too great, steam in the pipeWand chamberZforces the water therein up in tubeK, thus lifting the floatXand closing the steam entrance valveT′. Whenthe pressure of steam is low, the level of the liquid inZrises and liquid inZ′runs intoZ, the floatXfalls opening valveT′and allowing a greater flow of steam.
Gauge Glass for RegulaturFig.27.—Gauge Glass for Regulatur.
Fig.27.—Gauge Glass for Regulatur.
As it is often desirable to change the pressure of steam in the column at various points in the operation, the best regulators are usually provided with means to that end.
In order to measure the output of the still, there is attached thereto a gauge glass (Jin Fig.22), a diagram of which is shown in Fig.27. This consists of a jarAconnected at its lower end atbby an annular passageBto a chamberEfrom which proceed the tapsF. Centrally through the passageBpasses a tubecconnected at its lower end to the pipeCleading from the condenser. The tubeC cprojects upward into the jarAand is open at its upper end.
Continuous Distilling Apparatus, with External Tubular CondenserFig.28.—Continuous Distilling Apparatus, with External Tubular Condenser.
Fig.28.—Continuous Distilling Apparatus, with External Tubular Condenser.
Now the openingbis of a certain size and it is obvious that it will carry off a certain amount of liquid when running full or the amount allowed to flow out by the exit tapF. If now, more than that quantity of alcohol is produced, the alcohol will rise in the jarAuntil the rate of inflow and outflow is equal. If, however, the still is producing less than that quantity then the level of liquid inAwill gradually drop. Hence, by observing the level of the liquid inAand its constancy or variation in level, it is possible to tell precisely how much alcohol is running per hour and if the rate is steady. The jarAis provided with a capGwhereby an alcoholometer may be inserted into tubecfor the purpose of testing the strength of the liquor. The tapsFare for the purpose of collecting the first runnings, the pure alcohol and the last runnings or “feints.”
Detail of Chamber, Continuous StillFig.29.—Detail of Chamber, Continuous Still.
Fig.29.—Detail of Chamber, Continuous Still.
These principles are also embodied in the apparatus designed by the Vulcan Copper Works Co., of Cincinnati, and illustrated in Fig.28. The apparatus comprises the still, a wash heater and a condenser. The still is composed of a series of chambers from 12 to 24, the internal construction of which is shown in Fig.29. Each chamberconsists of a peculiarly perforated plateA, a drop pipeB, a sealC, into which the drop pipe from the plate above projects, and a central standardD.
Returning now to Fig.28, at the bottom of the column is a manifoldE, with pipesFandGwhereby either exhaust or live steam may be admitted.Hdesignates the discharge or slop valve, controlled by a floatIwhereby a constant level of slop or spent wash is kept in the bottom chamber.
To the right of the column is seen the slop testerJand hydrometerL, whereby the spent wash may be tested to see if the spirit is being properly extracted. The steam pressure is indicated by means of a floatNcontained within a vesselM, a tally weight moving against a scaleK, showing the pressure of steam entering through pipeOand acting against water contained in vesselM. Each chamber is provided with a manhole plateP, and a try-cockQ, whereby the operation of each chamber may be tested.Ris a gage glass to show the level of the slop in the bottom chamber.
At the top of the column are three rectifying chambers fitted with boiling pipes and trapsT, which distribute the ascending vapor and boil out the low wines returned from the wash-heater or fore-warmer.
The heater consists of a shell enclosing a series of tubes extending into an upper and lower chamber. The wash or “beer,” is pumped into the lower chamber of the heater, and passes upward through the tubes to the upper chamber from which is itcarried by a pipe to the plateAnext below the rectifying plates.
Detail of Perforated Plate AFig.30.—Detail of Perforated PlateA.
Fig.30.—Detail of Perforated PlateA.
The vapor from the column passes into the middle compartment of the heater and surrounds the beer tubes. The vapors give their heat to the beer and are thus cooled, the low wines being condensed and flowing back onto the uppermost rectifying plate, while the highly vaporized portions pass out to the condenser. This is of the same general construction as the heater, the vapor being cooled and condensed to liquid by the tubes through which a constant current of cool water is passed. This enters atUand passes out atV. These tubular condensers are particularly good as they may be easily cleaned. From the condenser the spirit passes to a discharge boxW. A portion of the flow passes into a test tubeX, provided with a hydrometer. A trapYand anair pipeZprovide means for the escape of gas.
Detail of Perforated Plate AFig.31.—Detail of Perforated PlateA.
Fig.31.—Detail of Perforated PlateA.
As before stated, the form of perforations in the plates of a column through which the vapor pass upward through the beer or wash is particularly important. The steam must be thoroughly diffused through the beer, or else particles of mash are carried up, accumulate around the perforations, baking there and clogging them up. The clogging and eventual stoppage of the perforations prevent the agitation of the mash carried on the plate, and a layer of mash accumulates and bakes on the head, or plate, above. Thus the operating capacity of the still is reduced and a larger quantity and greater pressure of steam is necessary with consequent waste of fuel.
Continuous Distilling Apparatus with Goose SeparatorFig.32.—Continuous Distilling Apparatus with Goose Separator.
Fig.32.—Continuous Distilling Apparatus with Goose Separator.
It is necessary then that the form of perforation or trap through which the vapor ascends shouldbe such that agitation of the beer shall be enforced in its movement across the plate, and that the steam shall be thoroughly diffused through the beer. In the Vulcan still above referred to, these results are accomplished by forming each perforation with a tongue, as shown in the fragmentary view of a plate, Figs.30and31, the tongues of all the holes being directed towards the periphery of the plate. It is claimed that by this construction the steam is diverted forward and injected into the beer, throwing the beer into vigorous motion, completely diffusing the steam and accelerating the motion of the beer from the sealCto the drop pipeB.
Fig.32illustrates another form of distilling apparatus manufactured by the same company, which is practically the same as the apparatus previously described except that it is provided with a “goose-necked” separator, interposed between the wash-heater and the enclosure. This consists of a series of convoluted tubes contained in a tank of cold water. The vapor from the heater passes into these convolutions. The heavier vapors are condensed therein and returned to the heater from which they descend into the column while the more volatilized vapors pass over into the final condenser. TheU-bends at the bottoms of each convolution act like so many low wine chambers in the still shown in Fig.9the highly heated vapor continually bubbling through the condensed vapor in theUbend and there becoming greatly enriched and concentrated.
This apparatus, it is claimed, is applicable to the distillation of grain, molasses or cane juice and will yield 170 or 180 per cent., or the equivalent to 85–90 G. L. or 34–36 Cartier.