US2117337A - Evaporator - Google Patents

Description

May 17, 1938. K. LOBL ET AL EVAiORATOR Filed May 20. 1956 MI 31 s i K 28 4 22 35 -5 3a 34 a" P 2 Sheets-Sheet 1 May 17, 1938. K. LOBL ET AL 2,117,337

EVAPORATOR Filed May 20, 1936 2 Sheets-Sheet 2 Fig.2

PM... May-11,1938- nvaromrron Karel Liibl and Karel Kiin Prun Gucchoslovakia Application May 20, 1936, Serial No. 80,794 V In Czechoslovakia November 3, 1934 5 Claims. '(01. 159-21) V This application has been filed in Czechosiovakia on. November 3, 1934, and in Austria on November 31, 1935. 1

The present invention relates to evaporators, more particularly evaporators for concentrating :sugar liquor, juice or saccharine solutions. The hitherto known constructions of evaporators having vertica'i'evaporator tubes have thedisadvantage that the boiling or evaporating of .the liquor to be concentrated does not proceed rapidly owing to the fact that transmission of heat is considerably retarded by the formation of condensate upon the sides of the tubes, this condensate forming a liquid jacketcovering the tube. In connection with sugar evaporators it is very impo'rtant that the boiling and concentration of the .sugar should take place very rapidly, in order to avoid the possibility of various detrimental chemicalprocesses being set upin the liquor during 20 slow boiling. .It has already been proposed to construct evaporators with vertical evaporator tubes in which the liquor passes through an intermediate tubular conduit which is heated both externally and internally by means of steam. In these constructions, the 'steam either does not move at all in the inner tube or only with a very small velocity and in thedirection of the flowing down condensate, and consequently it was impossible to obtain an intensive heat exchange.

'The boiling or-evaporation was therefore a very slow process.

,Theinvention relates to evaporators of the kind in which the liquor to be concentrated passes through an intermediatetubular conduit -or pasly in so constructing the evaporator that live, and

if desired, slightly superheated, steam is passed with considerable velocity through an inner heat- 40 through the' centre of the inner heating tube into the boiler, in which latter it moves-with slow velocity along the outer heating tubes. By this arrangement it is attained that the steam does not condense upon the walls of the inner heating tubes, but merely becomes slightly moist, although giving off a considerable amount of heat, and that the steam is condensed only in a spaceinto which it moves with small velocity in contact with the outer heating tubes. In this manner a very intensive heat exchange is attained and consequently also rapid boiling and concentration of the liquor.

In a preferred construction the inner heating tubes are closed at their upper ends, and the ing tube in an upward direction, and is discharged discharge of the steam from the inner heating tubes takes place through the centre by means of separate central tubes, which extend almost up to the upper end of the inner heating tubes. These central discharge tubes open at the lower ends into a chamber, and are adapted to be removed together with this chamber from the heating tubes. The heat passes from this chamber into a space or chamber surrounding the outer heating tubes. A chamber which is supplied with live steam is arranged under a chamber through which the liquor isadmitted. Under the cham-' her through which live steam is admitted is ar- .obtain a' progressive reduction of the cross sectional'area' of the passage through which the steam moves, the inner heating tubes have a circular cross section. which gradually changes into astar-shaped section or a section with undulating periphery so that the periphery of' the cross section of the inner tube remains practically the same upon'the whole length of the inner tube.

One embodiment of the invention is illustrated by way of example in the accompanying drawings, in connection with an evaporator particularly suitable for. concentrating sugar liquor.

In the drawings: v I Fig. 1 is a diagrammatic sectional elevation of a vertical evaporator,

Fig. 2 is a sectional elevation of a heater element,

Fig. 3 a section on line III-III of Fig. 2, Fig. 4 a section on line IV'IV of Fig. 2, Fig. 5 a section on line V-V of Fig. 2, Fig. 6. a section .on line V--V of Fig. 2 showing a modified construction, and v 'Fig. 7 the upper portion of a heater element in section.

Referring first to Figs. 1 and 2, a heater element say live steam, indicated by the letter P, passes l5 2. ber 'II and moves in the heating chamber "with 30 port 20, whilst the waste steam A is 5 the reduction 01- diameter is compensated for by 35 the appended claims.

with-great velocity through the median passage II upwards, and returns downwards through the central passage l1. 7 1

The outer heating tubes ll arerolled into or 5 otherwise fixed-in the-ends It. 36 of the heating chamber l8. Under ztheheating chamber I8 is arranged a lower liquor chamber 22 for the admission of the sugar or other liquor-S, the lat-- tcr rising through the, heater elements into an upe 1 per chamber 23. The liquor chamber 22 is closed v by a removable, bottom 33in which are fixed the inner heating tubes I: so that'the latter can be pulled together withthe removable bots 7 tom u, out of the evaporator. The inner rdis charge tubes l3 are'fixedwith the lower ends in" an inclined bottom 31, which divides a chamber 32 j intotwo parts, namely, a chamberffiiinto whichi live steam P is admitted and a cbllectin'gcham ber 21 into which moist/steam comingiromtheS- tubes is discharged. The bottoml33j and flange 34 of the'chamber 32 are-bothiixed to a'- I flange 35 of the heating chamber l8.; Thesteami passes from the chamber 21 upwards throughra tube 28 into the interior I! of the-heating chamsmail' velocity upwards sweeping -the outer heating tubes II. It transmits some heat to these outer tubes and iscondensed upon the *latter. The condensed water'K- is discharged through a discharged throughaportfl,

In order to facilitate the flowing'ot theliquor to be condensed through the heater elements'the diameter-of the inner heating tube t2 decreases 35 in the upward direction, thereby providing for a gradual increase in the cross-sectional area of the liquor in the direction of flow and in accordance with the increase of the volume'of theliquor. At r the same time, the cross sectional area of the 40 steam passing through the tube IZ-is progressive l'yreduced. V As the reduction of the diameter of the middle tube 12 in the upward direction would reduce the surface through which heat exchange takes place,

changing the cross section ofthe tube 12 from a V circular cross section at theglower end gradually 'into a star-shaped section or a section having an undulating periphery at the upper end; as shown 6. .This change of theshape of the cross section of the tube [2 is so eijiected that the pe-, riphery of the cross section of thetube remains practically the same upon the whole length of the tube. The same effect could beattained byf providing the tube l2 withsuitable corrugat ons increasingupwardlyin depth; w

In order to' guide the steamiate point or transmision from the'tube llinto the discharge 4 tube l3, guide members; 20, maybeprovided as 0 showninFigJl. be The described construction .is given only by way oi example and it will be understood that'various modifications maybe madewithout departing from thescope of the invention, as disclosed in weclaimz l. In-a'vertical evaporator more particularly for concentrating sugar; the combination of: a chamber containing vertical-'outerheating tubes; inner vertical heating tubes-arranged .within said outer tubes, said inner. heating tubes being closed at the top. and; open 'atithe bottom; discharge tubes arranged within said innerheating tubesand open at the top and at'the bottom andform- '75 ing with said inner heating tubes aninner annular passage; said outer heating tubes being open at the top and at the bottom and forming with the inner heating tubes annular vertical passages for the liquor to betreated; a liquor admission chamber arranged under and communieating with the lower endsof said outer heating tubes; means in said chamber ior admitting liq uorgto said outer heating tubes; aheating medium admission chamber arranged, under said liquor admission chamber andjsubdivided by a wall into two compartments, means in one of said compart- -,mehts for admitting heating medium to said 111- ner-heating tubes and said other-compartment beingin communication with the lower ends of 15" the dischargetubes located in said inner heating ;tubes,;and being also in communication with the chamber containing the outer heating tubes, ;wherebyheating medium passes from the admising tubes andaround the outer surface of said discharge tubes and then downwards through said :sionschamber upwards throushthe inner heatdischarge tubes and finally from the second compertinentof the admission chamber into the chamber containing the outer heating tubes,

whilst liquor passes from the admission chamber'f upwards through the annular passages between the inner and the'outer heating tubes.

2;;In a vertical evaporator, more particularly forfconcentrating' sugar, the combination of: outerjvertical heating tubes open at both ends; inner'heating tubes closed at the top and open at thebottom; dischargetubes open at the top andiatthe bottom located within said inner heatingtiibes; vertical annular passages between said 'outerandsaid inner heating tubes for the liquor to" be treated; the cross sectional area of the inner heating tube decreasing in the upward direction, I

and the cross sectional areaot the passages for the liquor increasing in the upward direction, the periphery of the inner tube changing from a circular shape at'the bottom of the tube toan' undulating shape in such a manner that the constant along the whole length of the inner fixed:in said partition walls and having a lowerlength of the periphery remains substantially end flange; a plurality or inner heating tubes 10- cated within said outer heating tubes, said tubes being closed at the topand open at the lower ends and fixed to a perforated plate adaptedto be fixed to the end flange of said container; a casing,

an upper end flange {or connection tosaid plate and said end flange, said casing being subdivided into two compartmentsby a perforated partition wall} a plurality of discharge tubes open at the top and at the bottom and fixed-in said partition wall and located within said inner heating tubes; means for admitting liquor to be treat-' ed to annular conduits formed between said outer and inner heating tubes; means for admitting live heating medium to the upper compartmentoi' said lower ca singand to the interior of said inner heating tubes; a conduitconnecting the lower compartment'oi said casing with said vertical container and means for disgharging said heat- -ing medium fromv the lower ends of said discharge tubes into the lower compartment of's'aid casing. 4. In acvertical evaporator, more particularly for. concentrating-sugar,- the sub-combination of:

heating tube closed at the top: andopen at the bottom; a tube located in said inner heating tube and open at both ends for discharging the heating medium from said inner heating tube; said inner heating tube having longitudinal undulations increasing in depth in the upward direction, whereby passages are formed between the outer and inner heating tubes the cross section of which increases in the upward direction, the heat exchange cross section of the inner tube remaining substantially constant for the whole length oi! the tube. Y

5. In a vertical evaporator, more particularly for concentrating sugar, the combination of:

outer heating tubes open at both ends; inner heating tubes within said outer tubes closed at the top and open at the bottom; internal discharge tubes in said inner heating tubes, open at both ends; means for introducing liquor into the annular spaces formed between said outer and inner heating tubes irom the bottom and discharging the liquor at the top; means for introducing live heating medium such as steam into the inner heating tube from the bottom to cause said heating medium to flow upwardly in said inner heating tubes around the outside of said discharge tubes and then downwardly through the interior of said discharge tubes; means for discharging said heating medium from the lower ends of said inner discharge tubes; and means for passing said discharged heating medium into a chamber containing said outer tubes to heat-said outer tubes.

KAREL Loan. mm xsm.

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