CA1036484A - Rotor thin-film evaporator - Google Patents

Abstract

Abstract of the Disclosure An evaporator comprises a device for uniform distribu-tion of liquid over the inner surface of upper drum crimp bulges, made as a plate rigidly secured on a rotor shaft and designed to cover the drum inner space and let steam pass through an annular clearance between the outer surface of the drum and a heat-exchanging surface of the casing, and a centrifugal separation device made up of sections, each being positioned between adjacent drums and having vertically disposed. wipers intended to discharge the separated liquid to the device for uniform distribution of liquid over the inner surface of crimp bulges of a lower drum.
The invention may have extensive applications in chemical petrochemical, food and pharmaceutical industries in apparatus intended for evaporation, distillation and concentration of thermally unstable materials.
The present invention can be most effectively employed as an evaporator of a vacuum rectifying tower.
The proposed rotor thin-film evaporator features better heat transfer and separation and a simpler design as compared to the prior art evaporators of the same type.

Description

1~36484 q'his invention relates to heat exchangers a-rld, ~n parti-cular, to rotor thin-film evaporators.
The inven-tion may have extensive ~pplications i~
chemical, petrochemical, food and pharmaceu-tical inau~trie3 in app~ratus intended ~or evaporation, distillativn and corl-centration of -thermally unstabl0 materi~ls.
q'he present inverltion can be most ef~ectively em-ploged as an evaporator of a vacuum recti~ying -tower.
~ he demand ~or thin-filrn rotor evaporators is explairled by that they ensure ~'mild" conditions ~or proces~es o~
distillation, eva~oration, conce~tra~ion and vaporization making it possible to avoid decomposition and polymerization o~ treated materials, especially thermally unstable ones.
Such aPparatus are characterized by modest h~draulic friction and lit-tle or no hydrostatic head o~ -the mercury column which permits vacuum treatment o~ materials (under a low pressure, at Presid o~ up to 1 mm Hg, i.e. lowering the temperature in the apparatus).
Besides, the residence time o~ materials in these ~ -apparatus is relatively short ~o~ the order o~ 5 to 40 sec.) as compared to other types o~ evaporators~ ~Jhich allows to cut the degree o~ thermal treatment to a mini-mum.
~ hin-~ilm rotor evaporators are peculiar in tha-t they combine high-inte~sity heat excha~ge and short time o~
residence o~ -treated materials.
~~

1(~364~

To this erld, several rotor -thin-filrQ evapocatiors h~v~
been designed, wherein the liquid Eilm on th.e heat-exchange surEace of an apparatus is produced by rotor wi~oers rigidly secured on a pO~Ner shaft and a 1-2 ~l wide cle~r~Qce i~
provided between the casing ancl wlpers.
~ he abo~e-describecl apParatus is cha:racterize~ a lirnited surface of heat exch ~l~e 'because o~ its com~licated desigrl, production process, assembly and operatiorl caused by the Eine clearance 'betwe~n the casing ~alls and rotor wipers and b~ the necessi~ty Eor d~namic balarlcirlg o~ the rotor to make allowance for the thermal strain of the rotor and the apparatus casing. ~'he apparatus is sensitive to heat and li~uid loads; the evaporator is most efficient wi-th big liquid loads, that is separa-tion o~ liquid drops :Erom the s~team flow becomes unreliable and insu~ficient wi-th 25 to 50 per cent of the ini-tial amount of the starting ma-terial being discharged froin the ~pP~ara~US~
~ he ploblem of increasing the heat-e~change surface has been partially solved by another type of rotor thin-film evaporator whereirl the liquid film on the appara~tus heat-excha~ge surface is produced by rotor wipers pivotally moun-Ged on the power shaft and sweeping UpOll the surface of the apparatus casing. ~he design of the apparatus permits building of larger evaporators.

10364~14 - 3-lloviever, aLmost all other dis~lvarltag~es of the kno~m evaporator are presen-t in this desi~rl. Besides, direct c~nt;act o~ ro-tor wipers wi-th the heat-excharlge sur~ace O:e the ~p-~aratu~
results in contamina-tiorl of the materlal, apart ~rom u~lde~ira-ble wearout o~ wipers and the casing.
r~`he inner surEac~ o~ the casing being rubbed OXl b~ 1t/iIJerS
is to be thoroughly treated -to make a polished sur~ace. 'L'he rotor wipers are -to be made of abrasion-resistarl-t materials exhibiting good anti~riction properties.
~ he reguired uni~orm ~it o~ each wiper to the casing heat-exchange sur~ace demands care~ul fabrication and assembly o~
the rotor.
~ he optimum thickness o~ -the film produced by this method upon the heat-exchange sur~ace is determined by a co~plex combination of factors: physical properties o~ the liquid on -the one hand and -the rotational velocity of the rotor, weight of wipers, their contact with the he~t-exchange sur~ace and design ~eatures o~ -the rotor~ on the other hand.
~he best operating conditions are consequently achie~ed withi~ a relatively narrow range of pressure upon the liquid by the wipers. I~ the opti-mum pressure is e~ceeded, the wipers may bare the heat transfer sur~ace (scratch off the ~ilm)9 whereas with lower pressure the liquid may fall through downwards.
~ 'he problem of increasing the heat-exchange surface Q3~;4~

( 1~0-200~o) ~ sirnpli~icatiorl O~' -t~le ~Pparatu3 design, it~
fabrica-tion and operation has been solved to a con~lderable degree by another desi~rl o~ a rotor thin-film evaporator wherein the liquid ~ilm upon the hea-t-exchange sur~ace is produced without anY mixin~ means. 'l'he liqui~ in this apparatus is dis-tributed by centri~u~al force b~ way o~ crim-ped drums mounted on the rotor ~la~t and perforated to disch~r-ge the liquid upon the hea-t-exchange surface o~ the apparatus casingO
rL'he designs of the prior art apparatus do not exploit all ways to intellsify heat exchange, namely: heat exchange intensi~ication by making use o~ all surface of the apparatus casing at the height of the ro-tor; heat exchange intensification by increasing the friction o~ steam and liquid (downflowing film). t~he lat-ter shortcoming is accounted for by the fact tha-t-the steam formed upon the heat exchanging surface is immediately evacuated through the perforation in the bulges of drum crimps into their inner space.
~ 'he design of the device for uniform distribution of liquid over the inner s-urface of bulges o~ ~rum crimps is too complicated and bulky. It co~prises a cylinder with a cogged base rigidly secured in the casing and disposed over the upper drum, a ~eeding device made as a sleeve secured on -the rotor and mounted in the cylinder, i-ts lower portio~ ~eaturing .

~3~4~ - 5 ~

radial pipes and a ril~ned ring placed under the ba~e of the fixed cylinder and secured in the upper part of the drum.
Such desi~n of a distribu-tor involves two irrelevant sta~es o~ liquid redis-tribution, namely: in-ter~edlate distributior o~ the liquid over the inner sur~ace of the ~ixed cylirlder and distribution of the liquid on the d~rum ring. It ~hould be taken in-to consideration that durirlg these stag~s o~
distribution the liquid may be carried away by a ~low o~
steam (secondary capture) co~ing into contac-t with splashes and drops ~ormed when the li~uid is discharged ~rom the ~eeder radial pipes and splashed from the sur~ace o~ the fi~ed cylinder and the dis-tributing ring of the d~um.
A device ~or separation liquid drops ~rom a steam-liquid ~low positioned inside the apparatus casing over the upper drum, to be more exact in the annular clearance between the casing and the feeder sleeve, comprises a centrifugal separating device. '~is device is made as inclined wipers with bent upper edges secured to the rotor and a number of vertical plates secured rigidly and radially to the casing, a concentric ring being mounted over these plates. This device does not secure complete separation o~ liquid drops. ~'he separation is single-staged and the steam ~low Passes through the centri~ugal separator. ~he separated liquid drops are thrown from side edges o~ the separator wipers to the ..

~36484 apparatu~ wall and the ~lying liqu~d drops come into contact with the steam ~low entering the separator, tha~ i~ se¢ondary capture o~ the li~id become~ po~ibl~. It ~hould be ~orne in mind that a~y lncrea~e o~ the separabor heighk, the ~um~er of wipex~ a~d their lead involves seriou~ co~plication~ due to i~admi~ble added drag of the apparatus ~o~ally opera-tin3; at a pressure of 1-5 mm Hg.
~ he apparatu~ is co~plicated a~d expensive to m~ke because of a plurality of per~orations (thousa~d~ or ken~
of thousa~ds) to be punctured in dep~e~sions of the drum crimp~
~or passing steam from the an~ular space between a drum a~d the casing i~to the inner æpace of ~ um. Besides, perforation is responsible ~or a eertain amouELl; of drops o~ liquid being carried away by the steam flow passing to the drum i~ner space, It i~ one o~ the principal objects of this invention to provide a rotor thin-film evaporator with inte~siIied heat oxcha~ge .
A ~urther object o~ thi~ i~ve~tion is to provide a rotor thin-film ev~porator ~ith a higher separation efficienc~
a~ compared to the prior art rotor thin-film evaporators of this t~.pe~

~.~364~34 _ 7 _ A s-till Purther object of the invention is to ~rovide a rotor thin-~ilm evaporator of a si~plier design as co~pared -to the ~nown evaporators o:~ this type.
'l'hese and other objects ~re achieved by that ~ rotor thir ~ilm evaporator casing wi-th a heat-exchange ~ur~ace, com~ri~es a ro-tor sha~t c~rrying crimped drums, each being ~ecured to bosses rigidlg ~astened to the sha~-t and per~orated to dis-charge the liquid on the heat-e~change sur~ace of the casing, a device ~or uniform distribution of liquid over an inner sur~ace o~ crimp bulges o~ each drum and a centri~ugal separa--ting device, wherein, in accordance with the invention, -the device for uni~orm distribution o~ liquid over the inner .
sur~ace of crimp bulges of the upper drum is made as a plate rigidl~ secured on the rotor sha~-t and designed to cover -the inner drum space and let steam pass through an annular clearan-ce betwèen -the ou-ter surface of the drum and -the heat-exchange sur~ace of the casing and the centri~u~ separating device is made o~ sections each being positioned between adjacent drums and having verticall~ disposed wipers i~tended ~or the discharge of the separated liquid to the device ~or uni~orm distribu-tion o~ liquid over the inner surface o~ crimp bulges o~ the lower drum.
A higher quality o~ separation is achieved with the help of the described apparatus design. Drops of liquid in the proposed aPparatus are separated from the steam-liquid ~low in --~0364~34 three s-ta~es: in the clearance between the rotor drum and the casing wall ~prelir~inary separation); at the entrance to the centri~ugal se-para-tin~ device when the ~low -turns -through 90; ~nd finall~, in each ~ection o- the centri~ugal separation device positioned between adjoinin~ drums. ~ch section o e the centri~ugal separating device Pas~e~ only a part of the ~team generated in the above section o~ the apparatus and the steam veloci-ty is t~lUS reduced in the separator making it~ opera-tion condition~ ~Quch easier.
The centrifugal separating device is made up o~ sections and each section is positioned between adjoining drums, having ver-tically and radially mounted wipers intended for the discharge of the separa-ted liquid to -the device ~or uni~orm distribution li~uid over the inner sur~ace of crimp bulges of the lower drum.
The apparatus needs no additional height to acco-mmodate the sections o~ the centrifugal separating device (non-opera-ting portion o~ the apparatus) since the available gaps between drums (cons-tructional) are more than suf~icient ~or the purpose.
The rotor length and overall dimentions of the appara-tus working part being the same, the heat-exchange surface o~ the proposed evaporator is larger by 20-25 per cent. '~he intensi~icatio~ is due -to the design wherein use is made o~
the upper part of the apparatus previously housing the centri-~03648~ _ 9 _ ~ugal separating device, the ~ipe connection to di chs~gesecondary stealrl ancl the device for uniform di~tribution of -the li~uid over the inner ~ur~ace o;~ crimp bulge~ v~ the u~per drusn. In this case this device is locate~ in th~ Upp9X
~art of the drurn and ma~e as a plate, wherea~ the ce~tri~ugal separ~ting device i5 rnade o~ sections and positio~ed between adaoining drums.
I~ is e~pedien-t, in accordance with the irLvention, that a plate be provided with a depression made as a c~lindrical cavity, its edge being a concentric rin~ with an in-ternal diameter being smaller than the minor diameter of the cylindri-cal cavity and bordering by its outer circumference on the inner sur~ace of the drum crimps.
rr'he proposed evaporator has a ~irnplier design of the device for uni~orm distribution of liquid over the inner sur~ace of crimp bulges of the upper drum since it comprises but one element, namely a plate rigidl~ secured on the rotor shaft and having a depression made as a cylindrical cavity its ed~e being a concentric ring with an internal diameter smaller than the rninor diameter of the cylin~rical cavity and bordering by its outer circumference on the inner sur~ace of the drum crimps~ 'L'he circular bead over the cylindrical cavi-ty forms the liquid into a vertical concentric layer equal to the bead width, thus securing even flowing of the liquid ~036~
over the inner ed~e of the concen-tric ring ~long its ~eriphery and i-ts further distribu-tion over the rin~ sur~ace a~ a~ even ~ilm. Be~ides, the ~late covers the space of the upper drum preve~-ti.ng s-team pene-tration ~rom above and let-tin~ it p~
-through -the annular clearance between the oute:r drum sur~ace and the casin~ heat-exchange surface~
r~he wipers, in accordiance with -the invention, ~e secured by -their butt ends in the bosses of' ad.joinin~ drums their cross-sec-tion is curvilinear and ou-ter edges are 'bent inside.
The separated liquid is, therefore, not thrown into the entering stea~n flow from -the surface of wipers, their cross-sections being curvilinear for reliahle separatior~ and ou-ter edges being 'bent inside. 'l'he separated liquid collects in the folds of ver-tical ou-ter wiper edges and flows as un-interrupted s-treams to the device for u~liform distribution of liquid over the iImer surface of the lower drum. Such con-struction of ~the centrifugal sep~rating device rules out the possibility of secondar-y capture of the liquid by the steam current.
It proved to be more e~ective technologically to make drum crimps continuous.
~ he drum str~lc-ture and the production process became much simpler. Besides, a labour consuming operation o~
perforating intricately shaped drum walls was eliminated.

/ -64~

The crimQed arurn ~ea-turine co~*ir:luous crirn-p recesses ~uncti.ons, aPart ~rom its 'basic prupose o~' distri~utirl~ th~
li~u.id. over -the heat-exch~n~e su:r~ace, a~ a prelir~ia~x~ r~epa-rator ~ld provides conditions for lettiag s-tear~l pass through the clearance be-tween the ~rums a~d. the a~I~aratus casing wall~
r~he ~rocess of heat-excha~e is intensi~ied a-t the expen.se o~ increased ~riction o~ s-tearn again~t liquid (~il.rQ) du~ to the axial s-team ~overlent in -the armular clearance be-tween the druras and the wall o~ the appara-tus casing.
~ his can be achieved'because the u~per dr-um space is covered from above by the plate and crimp recesses of drums are uninterrupted.
~ 'he i~ventio~ will now be described in gre~ter detail with re~erence to a speci~ic e~bodimen-t thereo.~, -taken in conjunction with the accompanying drawing~, wherein:
~ ig.1 is a longitudinal view o~ a thin-film eva-porator in accordance with -the invention;
Fig.2 is a sec-tional view taken along line II~lI o~
Fig.1.
'l`he rotor thin-~ilm evaporator illustra-ted in Fig.1 comprises a verticall~ installed, e~ternally heated casing 1 , with jackets 2 and pipe connections 3,4t5 for respectively feeding -the starting ma*erial, discharge of' the tower residue (or concentra-ted solution), outlet o~ secondar~ stearrl. Inside 1~6484 ~ 12 --the CaSing 1~ there is mounted a ~haf-t 6 o~ a rotor 7, carry~
ing crimped dru~s 8 and 8a with per~orations 9 (Fi~.2~ ~or dischar~ing -the liquid on-to a heat-exchan~e sur~ace 1~
of -the casing 1. 'llhe drums 8 and 8a are secured in their OIl bosses 11 arld 12 ri~idly fastened on the shaft 6.
'~hey are secured to rin~s 13 and 14 o~ the upper antl lower respec-tive bosses 11 and 12 wi-th the help of 'bands 15 (~i~.2) and screws 16. ~he walls o~ -the drums 8 and 8a ~ e longitu-dinally crimped -to divide -the liquid supplied to -their i~ner surface into separate s-treams freely flowin~ under gxavity along the inner surface of crimp bulges 17 wherein -the perforations ~ are made to eject the liquid onto -the heat-exchange sur~ace 10 of the casin~ 1. The shaft 6 of the ro-tor 7 carries devices 18 and 1g for uniform distribution of liquid over -the inner surface o~ crimp bulges 17 of each of the drums 8 a~d 8a and a centrifugal separating device.
~ 'he de~ice 18 for uniform distribution of liquid over the inner s~r~ace of -the crimp bulges 17 of the upper drum 8 is, in accordance with the invention, a plate 20 ri~idly secured on the shaft 6 of the rotor 7, positioned in the upper par-t of the drum 8 and fastened -thereto with the help o~ the band 15 a~d the screws 16 and fitted -to cover -the drum space from a'bove so that steam is let through arl annular cleara~ce 21 (Fi~.2) between the outer s-urface of -the drums 8 and 8a and ~03 ~ ~ - 13 -the heat-exchange surface 10 of the casing 1. '~'he plat~ 20 has a depression made as a cylindrical cavity 22 (Fig.1), it~
edge being a concentric ring 23 with an internal d.iameter (Fi~.2) smaller than a minor diameter ~2 ~ the cylindrical cavity 22 and bordering by its outer circurn~erence on the inner surface of crimp recesses 24 o~ the drurn ~ ~ue -to the prese-nce of a c-Lrcular bead over the cylindrical cavity 2~, the vertical concentric layer of the liquid formed thereurlder ~nd equal to the bead width secures uniform flow of the liquid over the inner edge of the concentric ring 23 along its periphery and its further distribution over the surface of the ring 23 as an even film discharged to the inner surface of cri~p bulges 17 of the drum 8.
Besides, -the plate 20 covers completely the space of the upper drum 8 preventin~ steam ~enetration into the drum space from above and providi~g conditions for steam passing through the annular clearance 21 between the outer surface of -the drums 8 a~d 8a and the heat-exchan~e surface 10 o~ the casing 1.
~ he device 19 for uniform distribution of liquid over the inner surface of the crimp bulges 17 of the lower drum 8a comprises the ring 13 of the upper boss 11 bordering along its periphery on the recesses 2L~, whereas the i~er edge of the ring 13 is provided wit~ a bead 25 preventing ~the liquid from being poured into -the space of the drum 8a.

- 14 ~
~036~34 ~ he evapora-tor casing 1 houses annular collec-tors 26 with grooves 27 placed between the adjoining d~'UMS ~ a to le-~the ~low of liquid over from each up~er s0ction to t~e rin~ 13 of the device 19 ~or uni~orrn dis-tri'bution o~ liquid over the inner sur~ace o~ crirnp 'bl~lges 17 o~ e~ch lower ~rum 8a.
'~he centri~ugal sepaXatin~ ~evice is, in accor~arlce with the invention, rrlade o~ sectionr~ 28, each O:e the~n being ~ositi-oned between the drums 8 and 8a and the adjoining lower drum~
8a and 8a. 'l`he device ~eatures ver-tically and radially rnounted wipers 29 (Fig.2) intended -to dir~ch~ge the separa-ted liquid -to the device 19 ~or uni~orrn dis-tribution of liquid over the inner sur~ace o~ crimp bulges 17 o~ the lower drum'8a~ ~he wipers 29 ~re spo-t welded'b~ their bu-tt ends to the bosses 13 and 1~ o~ each of the fur-ther adjoining drurns 8~ 8a and 8a and are curvilinear in their cross-sections. ~he wipers 29 have their outer edges 30 ben-t inside. ~he ring 14 o~ the lower 'boss 12 covers ~rom the b~tt the space o~ each drum 8 and 8a ~rom below and the ring 13 of the upper boss 11 covers ~rom the butt the space o~ each drum 8a ~rom above so that the steam ~low can en~er the space OL the d,rums 8 and 8a only between the wipers 29 o~ the cen-trif-ugal separating device o~
each section 28.
Reliable separation is thus achieved and the separated liquid is not -thrown ~rom the sur~ace o~ the wipers 29 by the centri~ugal force into -the incoming s-team ~low3 but collects ~0~64~34 - 15 -in the folds o~ the vertical outer edges 3~ o~ the wi~ers 29 and ~lows as vninterrupted strearns to the device 19 ~or uni-~orm distribution o~ liquid over the ir~er surface o~ crirnp bulges 17 of -the lower drum 8a, '~'he space o~ the lower drum 8a is separated frorn the circular sp~ce be-tween the drum~
and 8a and -the casin~ 1 by a lock. q'he lock is ~or[ned by a ferrule 31 secured to the casing 1, its upper part carrying a ring 32 with a ri~ alon~ i-ts inner ~eripher-y coupled with a lower ring 33 o~ the lower drum 8a, having a rim alon~ the outer diameter o~ the ring 33~
Pipe connec-tions ~ serve to feed the heat carrier (steam) into the jackets 2 o~ the evaporator and pipe connec-tions 35 are intended -to drain the condensa-te.
~ he evaporator operates as follows.
'rhe starting material is ~ed through the pipe connection 3 (Fig9 1) in-to the cylindrical cavity 22. ~,~en the rotor 7 revolves, the liquid rises on its walls by the centrifugal ~orce ~orming a vertical layer equal to the bead width. 'rhe liquid flows over the inner edge o~ the concentric ring 23 along its periphery and spreads evenl-y over its sur~ace as a ~ilm to be la-ter thrown off its outer edge to the inner sur~ace o~ the crimp bulges 27 o~ the drum 8 ~herein i-t is divided into separate vertical streams ~lowing freely by ~ravit-y to the per~orations 9 disposed at di~ferent elevation on the drum 8. rr~he strear~s of the liquid are thrown through lV3~484 the per~orations 9 to the heat-e~change sur~ace 10 o~ the casing 1, wherein -they ~orm a downward ~ilm permanentl~
turbulized by streams o~ the liquid. A part o~ the liquid evaporates upon the heat-exchan~e sur~ace 10 ~ld thc-, unva-porized liqui~ flows down into the rin~ col~ctor 26 ~ld then by the grooves 27 runs over to the distributirl~ ring 13 o~ -the lower drum 8a. r~`he liquid is ~ur-ther pushe~ by p,ravity from the ring 13 to the inner surface o~ the crlr~p bu~ges ~7 o~ the drum 8a wherein the cycle is repeated. 'I'he concen-tra-ted solution (or -tower residue) is drained through -the con-nection 4 and -the steam generated by ~the liquid evaporation moves downwards in the annular clearance 21 between the ou-ter sur~ace of the drums 8 a~d ~a and the heat-exchange sur~ace 10 o-f -the casir~ 1 o~ the evaporator. Owing to the ~riction o~ steam against liquid the heat-exchange process is in-tensi~ied. ~uring movement steam is partially (prelimina-rily) separated in the annular clearance 21 and at the entrance to each section 28 o~ the centrifugal separating device when turning 90. ~ter tha-t, the partiall~ separated steam passes through the centrifugal separation device wherein it is cleared completely of li~vid drops in each of the ~ections 28 and enters the space of lower drums 8a to be later discharged ~rom the eva~orator through the pipe co~nectiorl 5. r~he separated liquid is pushed ~rom the sur~ace o~ the wipers 2~ by the centri~ugal ~orce to the folds o~ the - 1~36484 ver-tical outer edges 30 o:~ the wiper~; 29, collects there and Ilow~; by gravity as uninterrup-ted streams to the ring '13 o:e the lower d:rum 8a ~nd to the irmer surIace o:~ -the cri~p bulge~ 17.

.

Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A rotor thin-film evaporator comprising: a casing with a heat-exchange surface; heating jackets mounted outside said casing; a rotor; a shaft of said rotor; crimped drums mounted on said shaft; bosses rigidly secured on said shaft;
each of said crimped drums having a butt end secured to said bosses; perforations made in side surfaces of each of said drums to eject the liquid to the heat-exchange surface of said casing; an annular clearance formed by the outer surface of each of said drums and the heat-exchange surface of said casing;
a device for uniform distribution of liquid over the inner sur-face of crimp bulges of the top of said drums made as a plate;
said plate being secured on said shaft of said rotor and in-tended to cover the space of said drum and let steam pass through said annular clearance; a device for uniform distribu-tion of liquid over the inner surface of crimp bulges of the lower of said drums; a centrifugal separating device made up of sections; each section of said centrifugal separating device being placed between said drums mounted on said shaft; said sections having wipers positioned vertically and radially and intended to discharge the separated liquid to said device for uniform distribution of liquid over the inner surface of crimp bulges of the lower of said drums.

2. A rotor thin-film evaporator as claimed in claim 1, wherein the plate has a depression made as a cylindrical cavity, its edges being shaped as a concentric ring, its inner diameter being smaller than the inner diameter of the cylindrical cavity and bordering by its outer periphery on the inner surface of the drum crimps.

3. A rotor thin-film evaporator as claimed in claim 1, wherein the wipers are secured by their butt ends to the bosses of said drums, their cross-sections being curvilinear and the outer edges bent inside.

4. A rotor thin film evaporator as claimed in claim 1, wherein the crimp recesses are made continuous.