US2774415A - Evaporator - Google Patents

Description

Dec. 18, 1956 H. H. BELCHER EVAPORATOR 4 Sheets-Sheet 1 Filed Oct. 25, 1951 INVENTOR HAROLD H. BELCHER jaw/5 9% ATI'O EYS Dec. 18, 1956 H. H. BELCHER EVAPORATOR 4 Sheets-Sheet 2 Filed Oct. 25 1951 m a K m w M Y 11i 4 Q a fill. k 1 V mi L 6 0 8 6 K lil Z ll 1 i a ll Lw 7 2 9 wk L i w INVENTOR H. BE LCHER HAROLD ATTORNEYS Dec. 18, 1956 H. H. BELCHER 2,774,415

EVAPORATOR Filed 001;. 25, 1951 4 Sheets-Sheet 4 I 5 20 l I 76 iii 64 I v; //0

INVENTOR 59 HAROLD H. BELCHER 2,774,415 7 EVAPGRATOR 'Harold 'H. Belcher, Orange, Mass, assignor't0i'Rodney Hunt Machine Company, Orange, Mass a corpora- "tion of Massachusetts Application October 25, 1951, Serial No.'253,126 15 Claims. (c1. 1596) The present invention relates to apparatus. for concentrating or evaporating liquids and separating entrapped liquid from the resulting vapor.

-My invention is illustrated in connection with an evaporator or concentrator of the type shown in Patent No.

2,596,086 and application Serial No. 216,217, filed March 17, 1951, by Hans C. Bechtlerfor Evaporator.

In the concentrating or evaporating of liquids, especially sensitive liquids such as milk, fruitjuices orthe like, it is important that the liquid be prot'ected from overheating which may injure the flavor, vitamin content, enzyme activity or the like. It has been found that such ov'er heating is most likely to occur at the'bottorn of the evaporator-concentrator where the liquid'i's most concentrated. The relatively thick viscous concentrate should be kept agitated and should be expelled fromthe apparatus quickly after evaporation.

Another problem in the construction of anevaporiatorconcentrator of this type is in providing ajsuitableloweir bearing for the rotor since this lower bearing should fulfill a number of exacting conditions. The bearing -should 'be' such that the rotor maybe easily removed and replaced for cleaning and'sterilizing. Properflubricationfis important because'the rotor rotates'at fairlyi'high speed and the lower bearing is subjected to fairly high temperatures. Where the bearing is lubricated by concentrate, lubrication may be inadequate. 'It'is also essential that this lower hearing be lubricated 'insu'ch a way that the lubricant does not contaminate the liquid being concentrated. I

One of the objects of the present invention isto vide'a thin film concentrator-evaporator in which overheating of the concentrate is substantially'preverited Another object is to provide a thin 'filmconcentratorevaporator in which the concentrate is quicklyremovaa after concentration; I

Another object is to provide a thin 'film concentratore'va'porator having an improved lowerbe'aririg. v

7 Another object isto provide a thin concentratorevaporator in which the rotor may be readily inserted and removed.

Another object is to provide a thin filin evaporat'oifconce'ntrator in which the lower bearing may be readily removed and replaced.

Another object is to provide a thin film-evaporatorconcentrator which may be effectively lubricate-d smiss:

contaminating the liquid being concentrated or evaporated.

These and other objects and advantages reside in certain novel features of construction arrangement and cornb'ination of parts as will hereinafter be more rally-set forth and pointed out in the appended claims.

Referring to the drawing:

Figure 1 is a vertical section of the upper part of'a thin film evaporator concentrator embodying my invention;'

Figure 2 .is a vertical section of the lower part'th'ereof;

Figure 3 :is an enlarged verticalsection 'of the lower bearing and vane structure of a thin film evaporator enibodying my invention;

, Figure 4 is a fragmentary horizontal section taken' 'on line 44 of 'Figure'3; V

, Figure 5jis a fragmentary vertical section taken an line;5+-5 of Figure 3;

Figure 6 is an enlarged fragmentary vertical section 2,774,415 Patented Dec. '18, 1956 ice 2 ofa'modifi'ed form of the lower bearing andoutlet section of the apparatus;

Figure 7 is'a'plan view of the bottom-' plate of the apparatus of Figure 6 shown removed from the-assembly;

Figure 8 is an enlarged fragmentary vertical section of a'further modification of the discharge section of the apparatus;

Figures is a fragmentary section taken along 'line'9' '9 of FigilfeiS; and

Figures .10 and ll-ar e "fragmentary views of a man- 'fied 'Tdischarge pipe installation which may be incorporated in the apparatus 'm'Figure 8. p

The general construction of an "eflicient film -'evaporatonconcentrator is described and-claimed in the aforesaid .Patent 2,596Q086 and application Serial No.

:is' of tubular construction andis normallyjoper'ate din verticalzpos'ition. The lower portion, indicated generally at 10, .-is' the evaporator'portion iof theapparatus 'and the upper portion, indicated generallyat 12, is the-separator portion; The liquid --to be concentrated is introduced :'through aj'pipe or fitting 14 Whi'cll'is generally located between thefevaporator 10 and' separ'ator 12 and flows down through the evaporatorf10 byrgravity. The con- .centrated liquid is withdrawn through a pipe or fitting 1:6 at the bottom of the evaporator =10 and vapor is discharged through a' pipe or conduit :18 above theseparator 12. V

The evaporator portion has a wall 20 which is normally cylindrical throughout substantiallytheentirelength 'of-the evaporating chamber. Thiswall 20 may betap'ered toform'a frusto-conical rather than-a'cylindrical'chamber and, while a cylindrical chamber is ordinarily vpreferred, it is to be understood that the term cylindrical when applied to the evaporator includes also a chamber of tapered or conical form.

The separating chamber 12 may be a'continuation of the evaporating chamber or may be larger-or' smaller than the evaporating chamber 10 but in the :preferred form", the separating chamber 12 formed by a wall 22. is'of larger diameter than the evaporating cha'mberzand the walls 20 and 22 are connected bya conical wall '24. A 'flange 26 is secured around the upper end of the "wall 22, above the pipe or conduit 18, and :is reinforced by braces. 28 van'd30 secured to pipe 18 and -a second pipe 32 respectively. These braces 28 311(1 may be welded to the ring 26 and to thepipes 18 and 32.

The top of the apparatus is closed by acap 34 re-- movahly secured on the top of wall 22 and' ring.26by screws or bolts 36 and a suitable :gasket 38 insures a pressure-tight seal. 7

An extension 40 on top of the cap 34 carries a bearing housing 42 at its upper end for receiving suitable bearings indicated generally at 44. The specific construction of these bearings forms no part of the pr'esentinverition but they are preferably of the anti-friction, self-aligning type. A shaft 46 is rotatably mountedv in the bearings 44 and the housing 42 is provided with oil seals 48 atits upper and lower ends to prevent leakage of oil along, the shaft. The shaft 46 inayalso be provided with an oil-flingercup 50 between the bearing housing and the cap 34 to 'aflord further protection against the leakage of oil or lubricant along the shaft.

A suitable pressure seal such as the water seal indicated generally at 52 is usually provided between the shaft 46 and cap 34 and various satisfactory 'forms of pressure seal are "known. A conical wall 54 extends between "joint of wall 22 and ea 'sa and the lowerend ofthe pressure seal 52 and serves to reinforce the pressure seal and protect it from the hot vapors.

The shaft 46 isarelatively short and is' detachably secured at its lower end to the rotor 56 as indicated generally at 58.

This connection is preferably protected from the hot vapors by a cap 60. This cap also simplifies the cleaning and sterilizing of the rotor assembly. a The rotor 56 of the apparatus is coaxial with the shaft 46 and could be a solid shaft but is preferably of tubular construction to save weight and cost.

The connection 58 between shaft 46 and rotor 56 is accessible through the large pipe or handhole 32 which is usually opposite the pipe or conduit 18 and isnormally closed by a door 62. The pipe or handhole 32 is sufiicientlylarge to permit a workman to reach into the chamber 12 for various operations such as adjustingor examining the seals 54,-disconn'ectingthe shaft 46 from the rotor 56'so that the cap, 34. and.shaft.46 may be removed as a, unit for cleaning .or repairing the apparatus or the'like.; Suitable means such as a gasket is provided to form a pressure seal between .the door 62 and handhole 32.

In my preferred form of apparatus, an annular flange V 64 is welded around the lower end of the wall 20 and a .flat plate 66 is, detachably secured to theflange 64 by bolts '68. ,A gasket 70 formsa pressure sealbe twe'en the .flange 64 and'plate 66. l I

.A sleeve 72 is. welded to the plate 66 and extends into the chamber substantially concentric with the wall 20.1, A bearing 74 which I preferto be of the waterlubricated type, is secured within the sleeve 72.. -Many suit- 'able bearingrnaterials are known and various rubbergraphite compositions are entirely satisfactory The sleeve .72 and bearing 74 are reinforced by 'a'frustoconical wall 76 which is welded to the sleeve 72 and plate The rotor 56 extends through the entire length of the separating cha'mber'12 and evaporating chamber 10 and a plug'or' ring 78 is threaded, welded or otherwise rigidly secured in the rotor. A stub shaft 80 in axial alinement with the shaft .46 is threaded, welded or otherwise firmly secured in the plug or ring 78' and'projects downwardl therefrom into the bearing-74. a

As shown in Figures 2 and 4, the rotor 56 extends downward beyond the plug or ring 78 outside the sleeve .72 into. close proximity 'with the conical wall 76; The sleeve 72'.extends upward beyond the bearing 74 into close proximity with the plug or ring 78 and protects -pheral notch respectively of the bearing 74 so that the lubricant, preferably water, may be, introduced through the. opening 86 and withdrawn through the. opening'88 by suitable means, not shown. The openings 86 and 88 are maintained under vacuum,-substantially the same asthe vacuum' on outlet 16 as hereafter described. In i order. to keep the lubricant from flowing over the sleeve 72'where it might contaminate the concentrate,

the stub shaft 80 is provided with a flinger ring 90' and the upper end of the sleeve 72 is recessed as indicated 'at 92, oppositethe flinger ring 90 so that the lubricant is returned to the top of the bearing 74 and withdrawn through grooves 82, notch .84 and'opening 88. e

The evaporating chamber 10 is preferably heated by a steam jacket formed by the Wall 94. and steam is introduced through a pipe 96 at the upper end of the jacket and is exhausted through a pipe 98 at the lower end of the jacket. 7 provided to exhaust the air from the steam jacketwhen operation is started and the wall 20 is preferably provided with ;means such as rings 102 at intervals toremove condensation from the surface of wall 20 allowing maximum contact of the steam. 1 a

If desired, an exhaust pipe may be The rotor 56 is imperforatethroughout its length and is sealed at'both ends. The rotor 56 is smaller than the evaporating chamber 10 formed by the wall 20, and within the chamber 10, and is provided with a plurality of blades or vanes 104 which extend outward from the; rotor into close proximity with the wall 20. In the em bodiment shown in Figures 1' and 2, there are four equally spaced vanes or blades 104 which project radially outward toward the wall 20. Ordinarily the vanes 01'' blades 104 are fiat strips of metal or the like and may be rigidly secured along one entire edge to the rotor 56' by. welding or the like, or the inner edges of the vanes.

may be recessed as indicated at 106 and the vanes welded to the rotor at spaced points as indicated at 108. This latter construction is less costly than the first form' but the first form may be easier 'to clean or sterilize. It is not essential that the vanes104 be flat radially nor that they extend longitudinally along the rotor but the fiat longitudinal vanes are simpler to make and attach to. the V rotor and are also lighter in weight.

The vanes 104 are continuous longitudinally and from the rotor 56 to close proximitywith the wall 20 so that every part of the space between the rotor 56 and wall 20 is acted upon by the vanes 104 when the rotor is rotated. Holes, notches or perforations in the vanes 104 will not prevent satisfactory operation so l'ong as 20 is kept as small as possible within reasonable mechanical limitations. Any number of vanes 104 maybe used but, because of the small clearances, it is important that the rotor 56 be balanced and the vanes are therefore preferably symmetrically disposed about the rotor.

As shown in Figure 2, the rotor 56 and vanes104 extend a substantial distance below' the bottom of the steamjacket into close proximity to the plate 66. The liquidat the lower part of the evaporator 10 is usually quite thick and susceptible to, burning, especially if any- 7 foam or liquid is allowed to collect in this lower portion.

,The vane portions below the steam jacket keep the foam and liquid agitated and by stopping the steam jacket short of the bottom, the foam and liquid are protected from excessive heat. My improved construction further protects the concentrate from over-heating by forcing the concentrate out of the apparatus.

The outletopening 16'is located adjacent the wall 20 and the frusto-conical wall 76 extends downward and .outward from the sleeve 72'into close proximity to the inner edge of the outlet'opening '16. This frusto-conical wall thus acts with the centrifugal force on the concen- 1 hate due to the action of-the rotor 56, to forcetheconcentrate downward; and outward, toward the outlet opening. I 7

Further, the lower ends of the vanes 104 are bent rearwardly of the direction of rotation asindicated at 110 in Figure 5 and these curved lower ends serve-'to force, the concentrate downward toward the plate 66' and outlet opening 16.

In each of the embodiments illustrated, thevanes 104 continue; along the rotor up into the separating chamber ,12 and a grid, consisting of a plurality of vertical,1radia1ly I vertical bafiles 112 and 114 are preferably welded together so that the entire grid may be inserted or removed from. the separating chamber as a unit. There is preferably a clearance between the lower horizontal bame ama- 1s 'Z1 14andthe wall-'22 so that'liquid can run downfthe wall 22-without interference and the top horizontal baflle 114 Eispreferably-higherthan the upper 'endsof vanes 104 "as s'hown'in -Fig'ure 1. The baflies 112 and 114 extend inward into close proximity to the vanes 104 so that the vap'or'cannot pass through the separating chamber without being acted upon by the vanes.

iAs' p'ointed out above, the evaporator-concentrator is operated '-in a vertical position and mounting brackets 116 r'n'ay besecured 'to the apparatus for securing the apparatus to suitable supports.

1' Theiapparatus is usually'operated under a vacuum and :a'condenser and pump,'notsho'wn, which may be of any suitable construction, are connected to the vapor outlet c'ohduitlS. The concentrate is discharged through the -pipe 16 and asuitable'trap, or pump, notshown, which maintains --the vacuum.

#In operationQthe shaft 46 maybe provided with a pulley, not-shown, above the bearing housing 42 and be driven by a suitable source of power suchas an electric motor, not shown. The rotor is rotated rapidly but the exact speed of rotation is not critical. The operation 'is successful when the shaft 46 and rotor 56 carrying the vanes 104 are rotated at a speed such that the circumferential speed of the vanes 104 is in thelg eneral rangeof ten to fifteen meters per second.

.The liquid to be concentrated is introduced through the pipe 14 which is ordinarily above the steam jacket to avoid burning of the incoming liquid and is preferably between the evaporating chamber 10 and separating chamber 12 although it may be located in the separating chamber 12. If desired,'a plurality of inlet pipes 14 .may' be symmetrically disposed around the wall 20 to equalize the cooling effect of the liquid and notches 118 may be provided in the vanes 104 opposite the inlet 14 to facilitate introduction of the liquid to be concentrated. .The wall 20 is heated by introducing steam at the desired temperature and pressure and the vanes 104 force Tthe liquidout against the heated wall'20 in a thin film. The liquid flows down the wall 20 by gravity to the bottom of "the evaporator housing and is withdrawn through the pipe 16. As the liquid fiows down the wall 20, vapor is driven off and this vapor passes upward between the rotor 56, wall 20 and the vanes 104 The moving vanes 104 drive entrapped droplets of foam or liquidoutward against the wall 20.

The rotor 56 is usually of fairly large diameter relative to the diameter of the evaporating chamber 10 and the vanes 104 are relatively narrow since narrow vanes are stronger and more rigid than wide vanes. However, it is desirable that there be sufiicient space between the rotor 56 and the wall 20 so as not to impede or unduly restrict the passage of the vapor upward through the evaporating'chamber 10.

Because the rotor 56 is imperforate and the vanes 104 are substantially continuous longitudinally and radially, the entire contents of the evaporating chamber 10 is at all times subject to centrifugal force resulting from rotation of the rotor and vanes. This tends to suppress the formation of foam and to force any foam which may be formed outward against the heated wall 20. Likewise, the rising vapor must pass between the vanes which tend to drive entrapped liquid or foam particles outward against the heated'wall 20. There is no place within the steam jacket portion of the evaporator portion 10 where liquid or foam can collect free from the action of the rotating vanes 10 All of the vapor from the evaporating chamber 10 passes upward through the separating chamber 12 which ,-is'norm'ally unheated except by the vapor. Ordinarily .the temperature in the separating chamber 12 is insufficient to cause substantial further evaporation of the liquid. The purpose of this separating chamber is to remove any unevaporated foam or liquid carried :by the vapor so that operating losses may be kept as low as 6,6 7 r l f l ille tf tfm yl egin'ec s'sia jy- 1 lblelto supply som outside jhjeat rogthejwallgzz =to pr vent" condensation in gthe. separating chamber-Which "m yqpc r'l I i to ensure' e' raction ofliq'uids-vvhicharegiiot'feasily,separated from their 'vap'ors. Such 'heat fshou'ld, however, he kept at a minimumjto avoid burning the separated 'liquidfflowing down the wall 22. a Inthepreferred fd m 'ofseparator'jshown, the length and Ispeed'of rotation 'of the rotor 56 and 'van'esf104 in the separating eonejl'is suchfthatithe vanes will move thrgugh at llea s'tjthe ,angular' distance between adjacent yanswliile vaporjis moving the length of the 'vanesvin "t e weat n 19, t a e ry pa t-b v pbr ri s' 15 ing through the separating zone "is acted 'upon byfa-"v'ane 104 moving through theyapor and. any -en'trapped roam or liquid will bejdrivenoutwardjbyjcentrifugalforce toward the wall 22. The'yertical bafiies -112prevent roa o o tha'ss a 'a m-a d liqu within m nt ratingphamberand thejhorizont'al baffles 114 preventthe separated foam and liquid from being carried upward by the vapor. The jtop' horizontal bathe-is located [above the ends of fthe, vanes 104 to prevent the vapor from 'carrying entrappedgfoam or liquid over the top of the grid. Any foamjand'liquidfinthevapor injthefsep'ar'atins hamb i z Pl'0i m w against the wa l by the vanes;104 andflowsdown the,,walls.22 and 24 b sk nt jthe vaporatin c m e as. pointed out in application Serial No. 2l6, 2l7., of Hans C. B e'cht ler referred to above, it is important that .the apparatus be easy to take apart for cleaning. and te li i V 1 m zapaal'al .th cpm ct n '5 m y b ched through handhole 32ja'nd Shaft?! disconnectedfro'm the 35 rotor 56. The cap 34carrying the shaft'46 may then be removedand the rotor 56- left in place with the pluglor ring 78 resting on the "sleeve 72. The interior of the apparatus may then be cleaned with a brush or by flushing. If more c omplete cleaning or sterilizih'g 'isfdesired-the 40 cap 34, shaft 46 and rotor 56 maybe removed as a unit and cleaned and sterilized outside the apparatus. The separator grid may be removed after removal of the cap 34 with or without removing .the rotor 56. i

If it is necessary or desirable to remove; the lower bearing for cleaning or sterilizing o-rforreplacement or repair, the plate 66 and entirebea'ring unit can be removed without disturbing the rest of the apparatusby removing the screws or bolts 68.

The apparatus described above has been foundfto be particularly effective in the production of concentrates haying relatively low viscosity.

However, to facilitate .efiicient removal ofthe more viscous concentrates 'such as eggs 'and gelatin, particular- 1y when suchsubstances are concentrated to 50% .solids or greater the modifications of the discharge-.section of the apparatus shown. in Figures, o through ll of the drawings may be preferred.

Referring'now more particularly to Figure 6,it -will.be seen that the bottom plate 66 has been replaced flw'ithra bottom plate 120, to which the'bearing; sleeve '72 and cone 76 are secured in the same manner as described in connection withFigure 3. The plate 12 0.is clampedhetween the flange 64 and a ringl22 by means of a plurality of bolts, not shown, which extend through the 65 ring 122, plate 120 and flange 64. Cored passages 124 and 126 are formed'in plate 120 for the purpose of supplying and withdrawing lubricant respectively in the-mam ner previously described. The outer ends of the passages 124 and 126 may be connected to a suitable lubricant circuit, not shown. Four arcuate slots 128 are provided in the plate 120, directly beneath the rounded tips of the rotor vanes, through which the concentrate may be discharged into a conical receiving section 130, which .is preferably welded at its upper end to the ring 122. At its lower end the conical section 130 carries a threaded fitting for attachment to a suitable container or pipe.

and. sterilizing.

Except for the modifications justdescribed, the evaporator-concentrator apparatus of Figure 6, is identical to that illustrated in Figures 1 and 2. The concentrate is forcedvthrough the slots 128' by the action of the vanes and the vane tips 110,'as in the case of discharge pipe 16,

the principal difierence being in 'the enlargement of crosssection of the discharge passages.

In the modification of Figure 8, the bottom plate 66 has been replaced with a detachable discharge section comprising a bottomplate 140, welded to a tubular secinstallation of the tubular section'142; A'seal 150 is provided at the juncture of tubular sections 20 and 142, to

'efiect a fluid-tight connection atfthis point. Lubricant ' passages 152 and 154 in plate '140 function' in the same 'manner' as passages 86 and .88 "previously' described. It

will be noted thatthe conicalreinforcing wall 156 which replaces the wall 76, has been extended almost to the tubular section 142. The contour of the bottom of the vanes 104 has been modified accordingly. The rounded construction of the lower tip ofthe vanes'may' be retained. However, the vanes will function properly if the 'vane tips are straight and coplanar with the vane body. The dischargepipe 158 is welded to the tubular section 142, and extends tangentially therefrom as seen in Figure 1 9,"exte'nding' downwardly at an angle preferably in the neighborhood of 45 or less, with respect to the plane o'f the bottom plate 140. By virtue of this construction, full advantage is taken of the centrifugal throw of the rotor blades, 'and the concentrate is taken "off the 1211142 7 tangentially of the direction of flow oftlie concentrate thus insuring a satisfactory discharge evenwhere highly viscous concentrates which tend to cling to tubular wall 142 are produced.

The discharge pipe 162, illustrated in.Figures l and 11 which is installed at the intersection of the bottom plate and the vertical tubular section is arranged to take full advantage of both the centrifugal and vertical flow components imposed on the concentrate by the rotor blades 104 which revolve in the directionindicated by the arrow. This installation of the discharge pipe would be most effectively utilized in a'disch'arge' section of. the type illustrated in Figure 8, modified so as to bring the slope of the reinforcing cone into agreement with that shown in Figure 3.

7 It is believed that the tangential discharge pipe installations shown in Figures 8' through: 11- will have particular utility in handling certain highly viscous concen- 'trates which are apt to'cling to the vertical wall of the apparatus, although the lighter and less viscous concentrates, which fall readily to the bottom plate, rnay be handled efliciently by the apparatus illustrated in Figures l7.

It will be understood that the apparatusof Figures 6 through 11 may be partially or wholly disassembled for cleaning,'inspection or repairs in the same manner as the apparatus of Figures 1-5. e

It is also to be noted that, where operating conditions require, additionaldischarge pipes or openings may be incorporated in all forms of the apparatus.

From the foregoing it will be apparent that I am able to'attain the objects of my invention' and provide a new and improved apparatus for concentrating liquids in which operational losses are minimized. The apparatus is simple in construction and the parts are so made that "the. apparatus maybe readily disassembled for cleaning 7 The invention maybe embodied in other specific forms without departing from the spirit or essentiahcharacterstrictive, the scope of the invention being indicated by 'the lower surface of the flange 148, to permit theflush Z outlets.

the appended claims rather than by the foregoing description, and all changes which come within'themeaning and range of equivalency of the claims aretherefore in tended to be embraced therein. p y

What is-claimed and desired to be secured by United States Letters Patent is: a .1. In an evaporator, including a, chamber having a substantially vertical cylindrical wall, a rotor rotatably mounted in said chamber substantially coaxial with said wall, a plurality of vanes radially spaced around said rotor and extending outward therefrom into close proxim ity with said wall, means for rotating said rotor, means atthe upper end of said chamber for introducingliquid to be evaporated, and heating means on said wall below said inlet; a substantially flat platedetachably secured to said chamber and closing the lower end thereof; and'said plate having a plurality of circumferentially spaced outlets for unevaporated concentrate, a downwardly and outwardly flared member secured atits base to said plate within said chamber substantially centrally of saidchamher, the outer edge ofsaid member being adjacent said outletsi to deflect the concentrate outward: toward said 7 outlets and bearing structure for said rotor rigidly secured to said plate, said plate having a first passage for.

supplying lubricant to the center of said bearing structure and an additional passage for removing lubricant from thereof 7 2 An evaporator as defined in claim; l in which the vanes extend downward into close proximity with said plate and said conical member.

3. Anevaporator as defined in claim 2 including means on the lower ends of the vanes for urging the unevaporated concentrate downward and outward toward said said bearing structure at a point adjacent the periphery 4. An evaporator comprising a wall forming a vertically elongated chamber, a rotor having a'coaxial open cylindrical-portion forming an open lower end thereof, said rotor being mounted for rotation in-said chamber substantially coaxially with said wall, a plurality of vanes radially spaced around said rotor, and 'extendingoutwardly therefrom into close proximity with said wall,

I means for rotating said rotor, means at the upper end of .said chamber for introducing a fluid to be evaporated,

a substantially flat plate detachablysecured to saidchan her and closing the bottom thereof, means forming an outlet for unevaporated concentrate in the lower end of said chamber, a stub shaft secured within said open cylindrical portion or said rotor and coaxial therewith, a bearing assembly secured to .said plate .Withinsaid chamber coaxial with said wall for rotatably and slidably receiving said stub shaft comprising an outer cylindrical sleeve, an inner cylindrical sleeve of anti-friction material,

saidinner sleeve being concentric with and shorter. than.

said outer sleeve and the upper part of each of said sleeves extending into said open cylindrical portion of i said rotor, means, for introducing lubricantwithin said isticsthe'reof. The present embodiment istherefore to r inner sleeve, means for preventing lubricant from passing over said outer sleeve, means for withdrawing lubricant from between said sleeves, a frusto-conical member en circling said bearing and secured at. its upper end tozsaid bearing and at its lower end-to said plate, said member being secured to the plate at substantially the same distance from the center of the plate as the inner edge of said outlet, the vanes on said rotor extending into 1 close proximity to said member and said plate, and means for.

said inlet to a point spaced above said plate.

heating the wall of said chamberfrom a point beneath 5. An evaporator as defined in claim 4 including '7 .means for releasably securing said plate and bearing'to said wall in fluid pressure tight relation thereto.

6. An evaporator as defined in claim 4 in;which the heatingmeans comprises a heating jacket surrounding said wall from beneath said inlet to a point adjacent the top of said bearing.

7. In an evaporator including a chamber having a substantially vertical cylindrical wall, a rotor comprising a hollow tube rotatably mounted in said chamber substantially coaxial with said wall, a plurality of vanes radially spaced around said rotor and extending outward therefrom into close proximity with said wall, means for rotating said rotor and means at the upper end of said chamber for introducing liquid to be evaporated; a plate closing the bottom of said chamber, means forming an outlet for unevaporated concentrate in said plate adjacent said wall, a stub shaft secured within said tube adjacent the lower end thereof and coaxial therewith, a hearing secured to said plate within said chamber coaxial with said wall for rotatably and slidably receiving said stub shaft, and a frusto-conical member encircling said bearing and secured at its upper end to said bearing and extending downwardly and outwardly into engagement with said plate adjacent the inner edge of the outlet to direct unevaporated concentrate toward said outlet.

8. An evaporator as defined in claim 7 in which the hollow tube of said rotor extends downwardly over the upper part of said bearing into close proximity with the top of said frusto-conical member, and the vanes on said rotor extend downward from said tube into close prox imity with said frusto-conical member and said plate.

9. In an evaporator, including a chamber having a substantially vertical cylindrical wall, a rotor rotatably mounted in said chamber substantially coaxial with said wall, a plurality of vanes radially spaced around said rotor and extending outwardly therefrom into close proximity with said wall, means for rotating said rotor and means at the upper end of said chamber for introducing a liquid to be evaporated; a substantially flat plate closing the lower end of said chamber, said plate having a plurality of circumferentially spaced openings to provide outlets for unevaporated concentrate, and a downwardly and outwardly flared member secured at its base to said plate within said chamber, the outer edge of said member being adjacent the inner edge of said 'circumferentially spaced openings to deflect concentrate toward said outlets.

10. An evaporator as defined in claim 9, together with a conical receiving member for the concentrate and means detachably securing said member to the lower side of said plate.

11. 'In an evaporator including a chamber having a substantially vertical cylindrical wall, a rotor rotatably mounted in said chamber substantially coaxial with said wall, a plurality of vanes radially spaced around said rotor and extending outward therefrom into close proximity with said wall, means for rotating said rotor, and means at the upper end of said chamber for introducing a liquid to be evaporated; a discharge section adapted to be detachably secured to the lower end of said evaporator, comprising a tubular member forming a continuation of said vertical cylindrical wall, a substantially flat plate rigidly secured to the lower end of said tubular member to close said chamber, an outlet for unevaporated concentrate in said tubular member adjacent said plate and a downwardly and outwardly tapered member secured at its base to said plate within said chamber, the outer edge of said member being adjacent said outlet to deflect the concentrate toward said outlet.

cumferentially spaced openings to provide outlets for unevaporated concentrate, a bearing structure on said plate for rotatably and slidably supporting said rotor substantially centrally thereof, said plate having inlet and outlet passages for lubricant for said bearing formed in the portions of said plate intermediate said openings, and a downwardly and outwardly flared member secured at its base to said plate within said chamber, the outer edge of said member being adjacent the inner edge of said openings to deflect concentrate toward said outlets.

13. An evaporator as defined in claim 12 together with a conical receiving member for the concentrate, and means detachably securing said member to the lower side of said plate.

14. An evaporator comprising means forming a vertically elongated chamber of circular section, a rotor rotatably mounted in said chamber substantially coaxially thereof, said rotor having a stub shaft adjacent its lower end, means for rotating said rotor, means at the upper end of said chamber for introducing a liquid to be evaporated, a plate detachably secured to said chamber and closing the bottom thereof, said plate having a plurality of circumferentially spaced openings forming outlets for unevaporated concentrate, a bearing assembly mounted on said plate within said chamber coaxial with said wall for rotatably and slidably'receiving said stub shaft, said bearing assembly comprising an outer cylindrical sleeve, an inner cylindrical sleeve of anti-friction material, said inner sleeve being concentric with and shorter than said outer sleeve, means forming radially extending inlet and outlet lubricant passages in said plate, said inlet passage communicating with the interior of said inner sleeve and said outlet passage communicating with the interior of said outer sleeve, a frusto-conical member encircling said bearing and secured at its upper end to said bearing and at its lower end to said plate at substantially the same distance from the center of the plate at the inner edge of the outlet, and means for preventing lubricant from passing over the said outer sleeve into the interior of said chamber.

15. An evaporator comprising means forming a vertically elongated chamber of circular section, a rotor rotatably mounted in said chamber substantially coaxially thereof, said rotor having a stub shaft adjacent its lower end, means for rotating said rotor, means at the upper end of said chamber for introducing a liquid to be evaporated, a plate detachably secured to said chamber and closing the bottom thereof, said plate having a plurality of circumferentially spaced openings forming outlets for unevaporated concentrate, a bearing assembly mounted on said plate within said chamber coaxial with said wall for rotatably and slidably receiving said stub shaft, said bearing assembly comprising an outer cylindrical sleeve, an inner cylindrical sleeve of antifriction material, said inner sleeve being'concentric with and shorter than said outer sleeve, means forming radially extending inlet and outlet lubricant passages in said plate, said inlet, passage 12. In an evaporator including a wall forming a ver- I communicating with the interior of said inner sleeve and said outlet passage'communicatin'g with the interior of said outer sleeve, a conical receiving member for the concentrate and means for detachably securing said mem- I her to the lower side of said plate, and means for preventing lubricant from passing over said outer sleeve into the interior of said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,403,804 Merrell Ian. 17, 1922 1,466,579 Collver 'Aug. 28, 1923 2,066,281 Traylor etal Dec. 29, 1936 2,596,086 Muller May 6, 1952 FOREIGN PATENTS 12,096 Great Britain June 13, 1901 330,805 Great Britain June 19, 1930

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