US2493220A - Rotary drum evaporator with concentric evaporating chambers - Google Patents

Description

Jan. 3, 1950 J. E. BIBBY ROTARY DRUM EVAPORATOR WITH CONCENTRIC EVAPORATING CHAMBERS 4 Sheets-Sheet 1 Filed Aug. 15, 1946 m I. n e U n I A ltorney Jan. 3, 1950 J. E. BIBBY 2,493,220

ROTARY DRUM EVAPORATOR WITH CONCENTRIC EVAPORATING CHAMBERS Filed Aug. 15, 1946 4 Sheets-Sheet 2 F/GZ. l4 /7 Inuenlor Z Z By Attorney Jan. 3, 1950 J. E. BIBBY 2,493,220

ROTARY DRUM EVAPORATOR WITH CONCENTRIC EVAPORATING CHAMBERS Filed Aug. 15, 1946 4 Sheets-Sheet 3 A ltorney Jan. 3, 1950 J. E. BIBBY ROTARY DRUM EVAPORATOR WITH CONCENTRIC EVAPORAT ING CHAMBER 4 Sheets-Sheet 4 Filed Aug. 15, 1946 F/GS Invenlor Bz6&y y

\ A llorney Patented Jan. 3, 1950 UNITED STATES, PATENT OFFICE ROTARY DRUM EVAPOBATOB GON- CENTBIC EVAPOBATING CHAMBERS James Edward Bibby, Birkenhead, England, '18- signor to J. Bibby & Sons Limited, Liverpoo England, a British company Application August 15, 1946, Serial No. 890,784 In Great Britain September 6,1945

'1 claim. (Cl. 202-236) liquids having a tendency to foam or froth during evaporation, or liquids containing small quantities of finely divide'd solids.

A highly successful application of the invention is to a machine for the treatment of .oil which has been extracted by means of solvents, the machine being used after the extraction process has been completed to separate and recover" the solvents from the oil. A further application of. the invention is to a machine for the deodorization and like treatment of oils, e. g. palm oil, cotton seed oil, soya bean oil and the like.

According to the present invention there is provided an evaporator comprising a casing having a heating jacket, a drum or like member in said casing and having its. peripheral surface spaced from the interior of the casing to form an evaporation chamber, either or both the easing and the drum being relatively rotatable, inlet means for introducing liquid to be treated (e. g. 011 and solvent) into'said evaporation chamber and an outlet for the evaporate (e. g. solvent).

In the preferred embodiment of the invention the casing is stationary and the drum is rotated.

'Due to the rotation of the drum, onto the surface of which the mixture of oil and solvent is fed, centrifugal force acts to maintain a skin or film of the liquid on the interior face of the casing or heating jacket so that said film is rapidly heated and the solvent evaporated. Preferably there are blades in the evaporation chamber which serve continuously to change the surface of the liquid in contact with the heating surface. Thisresults in a rapid and highly ellicient transfer of heat from the heating Jacket to the liquid. The film of liquid may be traversed along the length of the casing, in contact with the heating jacket, by a series of angularly disposed plates or blades which work in the evaporation chamber. Conveniently some, at least, of the blades are arranged to scrape the interior face of the casing.

To provide a second-stage" evaporator, the interior of the rotatable drum-like member may be divided by radially spaced circumferential partitions into a plurality of annular chambers.

The innermost chamber has an inlet for steam or other gaseous media (hereinafter referred to as steam) and an outlet for residual liquid and theoutermost chamber has an inlet for the liquid to be treated further (say, oil and solvent) and an outlet for the steam, or vice transfers it to the next chamber.

versa. Transfer means are provided in the partitions for the transfer of oil and solvent'from one chamber to the next, said transfer means including a scoop-like member which receives. or gathers, the oil and solvent, from the body of cascading oil and solvent built up at one side of each chamber due to the rotation thereof, and This process of transfer continues from annular chamber to annular chamber'until the oil and solvent have. passed from the outermost chamber to the inner most chamber (or vice versa) via a very long path and in contact with and, at least in part, counter-current to the steam. Due to this long path of flow in the form of a rapidly moving cascade the steam evaporates and carries of! with it the solvent in an eflicient and eflective manner and leaves the oil substantially, if not completely, free of solvent. Preferably the trans-'- fer of oil and solvent from one annular chamber to another takesplace alternately at opposite ends of the chambers so as further to increase the distance the oil and solvent have to flow counter-current to the steam.

Preferably each of the aforementioned partltions comprises at least two and preferably more arcuate elements or plates spaced apart or staggered radially to form apertures or passages in said partitions for the transfer of steam and evaporated solvent from one chamber to the next via a sinuous path and counter-current, at least in part, to the oil and solvent. The combination of aprimary evaporator having a steam jacket and rotating drum-like mem-'- ber, forming an evaporating chamber, and a sec-.-

ondary evaporator comprising a series of annular chambers as just described, provides a particu'- larly compact and efllcient machine.

One specific embodiment ,of the invention as applied to an evaporator for the evaporation and recovery of solvent from oil will now be described by way of example with reference to the accompanying drawings, the figures of which are semi-diagrammatic in character- ,On the drawings: L Figures 1 and 2 are complementary'views showing the machine in sectional elevation, the section being taken vertically through the axis of the machine: I Figure 3 is a cross-section on the line 1II1I|I of Figure 2;

Figure 4 is a fragmentary detail perspective view of a part of the scraper construction for the primary evaporator part of the machine, and Figure 5 is a fragmentary detail sectional view of the scoop construction which forms a part of the secondary evaporator part of the machine.-.- A

The machine comprises a cylindrical casing Ill closed at its ends by end plates Ii having can-.- trally-located bearings ii for supporting a roaaaaaao 3 tatable shaft It. A drum 2. is located within the casing it and is spaced from the interior thereof to form an annular evaporation chamber it.

steam or other heating jacket i'l (hereinafter called a steam packet) surrounds the casing, this steam jacket being provided with an inlet it for steam and with the necessary drainage means it and the like. The steam jacket is lagged, as indicated at 20, to prevent loss of heat. An inlet ii for the mixture of oil and solvent is provided at one end of the casing II and enters the aforementioned evaporation chamber it tangentially with respect to the drum-like member it, IS. Rows of radially Pr jecting blades 2: are punched up out of the arcuate sections of the bladed structure II of the drum. There are also blades 24 or like members resiliently mounted on the armate sections II and pressed into contact with the interior surface of the casing ll so as to scrape said surface. The blades 22 and It ensure changing of the liquid film on said interior surface continuously and this promotes rapid evaporation. The blades 24 are inclined'with respect to the plane of rotation of the drum so that as the drum rotates the liqud is traversed along the evaporation chamber it towards the end 23 thereof 'remote from the inlet II for oil and solvent. It will be noted that the arcuate sections overhang their supporting brackets 2| as indicated at Ila to provide the required resilient support for the blades 24. The end of the evaporation chamber it, remote from the inlet II, is open as indicated at 28 and the oil and any remaining solvent therein pass from the primary or first-stage part of the machine via this opening into an annular cavity 20, between the end plates II and II, from which it iiows to the secondary evaporator part of the machine hereinafter described, by way of a transverse collecting tray "a, a spout 20b, and an opening lie in the right-hand end plate ll. Solvent evaporated oil from the mixture of solvent and oil in the evaporation chamber it finds its way to, and passes from, the machine via an outlet duct it at the end thereof remote from that at which the oil is discharged.

The secondary evaporating part of the machine is housed within the drum 2. and comprises a series of radially spaced circmnferential partitions ll secured at their ends in the end plates i4 and located concentrically one within the other so as to divide the interior of the drum into a plurality of annular chambers I2.

Each of the annular partitions 3i comprises several arcuate-plate sections, the ends or which overlap, the sections being displaced or staggered radially with respect to one another so that where they overlap a passage-way a is formed for the flow of steam'and evaporated liquid (e. g. solvent) from one chamber to the next. The axially extending edges 34 of the plates in the neighbourhood of said passages are turned inwardly whilst bailles ll are located just ahead of the exit ends of said passages so that steam flowing from the passages issues in a radial direction. The arcuate sections of each partition 3| are maintained in their radially spaced relationship by spacing pieces 38. Each partition ll carries several radial projecting scoop-like members 31 which open into the passage-ways it for the 4 transfer of oil and solvent from one annular chamber 32 to the next. These scoop-like members are located alternately at opposite ends of the chambers.

The outermost of the annular chambers 32 communicates with the opening :lc by which the partially treated oil is discharged from the primary evaporator part of the machine above described. The innermost of the annular chambers 32 communicates with an opening ll in the right-hand plate II, which opening in turn communicates with a sump ll for receiving the oil after final. treatment. the oil passing from the sump. via a port I, to a pump 42 by which it is discharged from the machine. An inlet It is provided for the injection of steam into the innermost of the chambers 82 via theport 80..

The operation of the machine above described is as follows:

The mixture of oil and solvent from which thesolventistobeextractedandrecoveredisintroduced, via the inlet ii, into the primary evaporation chamber II and, due to the rotation of the drum member ll. II and centrifugal force and the blades 22 and 24, is caused to become a rapidly moving and changing illm on the interior face of the casing ll 01 the steam jacket II. In its passage from one end of the evaporation chamber it to the other the liquid is heated and a part, at least, of the solvent is driven oil! and passesfromthemachinetoacondenserviathe aforementioned vapour outlet 8|. The liquid oil passes from the primary evaporation chainber II to the outermost of the annular chambers 32 of the secondary evaporator and, due to the rotation of the inner drum and partitions ll, builds up as a ment-like body of cascading liquid to one side of the drum. When this body of liquid reaches a predetermined thickness some of it is gathered by, or cascades into, the scoops 31 on the neighbouring partition and is transferred into the next annular chamber 82 where it again builds up into a segment-like body of cascading liquid at one side of the chamber 32.

.1hisliquidinturnisgatheredinthes'coopafl of the neighbouring. partition and transferred to the next chamber II. This procedure is carried on right through the several annular chambersandinasmuchasthescoopsarearranged alternately at opposite ends or the drum the liquid flows sinuously through the several chambers from the outermost to the innermost. The manner in which the liquid builds up at one side of each chamber is indicated diagrammatically atLinFigureS. Whilstthisiiowofoilandsolvent is taking place in the one direction through the chambers 32, steam is flowing in the opposite direction through said chambers and is evaporating and taking up the remaining solvent from an the oil and carrying it away via the aforementioned vapour outlet II. It is appropriate to mention that the open mouths of the scoops I1 and the steam outlets II from the chambers 32 lead with respect to the direction of rotation as of the chambers. the direction of rotation being indicated by the arrow in Figure 3. The segmentshaped body L of liquid at one side or each annular chamber 32 tends, of course, to remain stationary relatively to the rotating structure 10 once it has been built up to a height and thickof the liquid. The stage at which liquid is transferred from one annularchamber 32 to the next depends, of course, on the position of the scoops 31. i. e. the spacing of the scoops from the-neighbouring partition 3| from which they gather the liquid.

It is convenient, in order to facilitate assembly of the several elements forming a partition 3!, to

secure such elements to the end plates of the drum by means of bolt-like devices 44 which are slid into holes in the end plates l4 and are trapped against being removed therefrom, as each succeeding partition element or plate is located in position.

In some cases the secondary evaporation part of the machine may be dispensed with, whereas in other cases the secondary part may comprise a machine separate from (i. e. not within) the primary part. A machine of this character forms the subject-matter of our co-pending application for Patent No. 690,765 filed August 15, 1946 now Patent 2,484,445 granted October 11, 1949.

A condenser and suction apparatus are generally connected to the machine as indicated diagrammatically at 45 and 46 respectively in Figure 1. For certain purposes (e. g. for the deodorization of oils) it is desirable to maintain a high degree of vacuum in the machine.

In some cases the passage-ways 33 may be closed entirely, or be dispensed with, in the neighbourhood of the spacing pieces 36. In such an arrangement the steam flows counter-current to the oil by way of the scoops 31.

I claim:

1. An evaporator, comprising a casing, a cylindrical drum rotatably mounted in said casing with its axis of rotation horizontal and having its peripheral surface spaced from the interior surface of the casing to provide an evaporation chamber between said surfaces, aheating means for said chamber, inlet means for introducing liquid to be treated into said evaporation chamber, an outlet for vapor, discharge means for residual liquid and blades on the drum working on the interior surface of the casing, some at least of the blades extending in a slantwise direction around and along the peripheral surface of the drum, spaced apart apertured circumferential partitions within the drum dividing it into a series of annular cham-' bers, means connecting the evaporation chamber to the outermost annular chamber for the passage of residual liquid thereto, at least one scoop on each partition and in register with an aperture therein for scooping up liquid from a body of liquid thrown by centrifugal force due to the speed of rotation of the drum against the outer peripheral surface of an annular chamber, saidv scoop transferring the liquid inwardly to the next inner chamber as the drum rotates, means for passing steam through the annular chambers, an outlet for vapor and an outlet in the innermost chamber for residual liquid.

2. An evaporator, comprising a casing, a cylindrical drum rotatably mounted in said casing with its axis of rotation horizontal and having its peripheral surface spaced from the interior surface of the casing to provide an evaporation chamber between said surfaces, heating means for said surface of the casing, some at least of the blades extending in a slant-wise direction around and along the peripheral surfaceof the drum to cause the liquid to move along the evaporation chamber, spaced-apart apertured circumferential par titions within the drum concentrically arranged and dividing the interior of the druminto several annular chambers, means connecting the evaporation chamber to the outermost annular chamber for the passage of residual liquid thereto, means .for discharging the residual liquid from the inner? most annular chamber,- means for passing steam through each of the annular chambers in turn countercurrent to the liquid, an outlet means for vapor from the annular chambers and at least one scoop on each partition and in register with an aperture therein for scooping up liquid from a body of liquid thrown by centrifugal force due to the speed of rotation of the drum and lying against the outer peripheral surface of an annular chamber and transferring the liquid inwardly to-the next inner chamber as the drum rotates.

3. An evaporator, comprising a casing, a cylindrical drum rotatably mounted in said casing with its axis of rotation horizontal and having its peripheral surface spaced from the interior surface of the casing to-provide an evaporation chamber between said surfaces, heating meansthe blades being arranged in several axially extending rows, the blades in One row being staggered with respect to the blades in a neighboring row, and other blades extending in a slant-wise chamber, inlet means for introducing liquid to I direction around and along the peripheral surface of the arcuate plates, spaced-apart apertured partitions within the drum concentrically arranged and dividing the interior of the drum into several annular chambers, means connecting the residual liquid discharge means in the evaporation chamber to the outermost of the annular chambers, means for discharging the residual liquid from the innermost annular chamber, means for passing steam through each of the annular chambers in turn countercurrent to the liquid, an outlet means for the vapor from the annular chambers and at least one scoop-on each partition and in register with an aperture therein for scooping up liquid from a body of liquid thrown by centrifugal force due to the speed of rotation of the drum against the outer peripheral surface of an annular chamber and transferring the liquid inwardly to the next inner chamber as tions spaced apart radially and overlapped at their ends to form the apertures for the flow of vapor from om. annular chamber to the next.

5, An evaporator as claimed in claim 2, wherein the partitions forming the annular chambers each comprises several imperforate arcuate sections spaced apart radially and overlapped at their ends to form the apertures for the flow of vapor from one annular chamber to the next,

baflles being provided where one annular cham- 7. ber communicates with another for the passage of vapor; V

6. An evaporator, comprising a casing, a cylindrical drum rotatabiy mounted in said casing with its axis of rotation horizontal and having its peripheral surface spaced from the interior surface of the casing to provide an evaporation chamber between said surfaces, a heating means for said chamber, inlet means for introducing liquid to be treated into said evaporation chamber, an outlet for vapor, discharge means for residual liquid, blades projecting outwardly from arcuate plates mounted on the drum concentrically therewith, some at least of the. arcuate plates having a resilient part which carries the scraper blades and maintains them operative to scrape the interior surface of the casing, some of the blades being arranged in several axially ex tending rows, the blades in one row being staggered with respect to the blades in a neighboring row, other blades extending in a slant-wise direction around and along the peripheral surface of the arcuate plates to cause the liquid to move along the evaporation chamber from the liquid inlet means to the residual liquid discharge means, the latter being displaced along the chamber with regard to said liquid inlet means, spacedapart partitions comprising several imperforate arcuate sections spaced apart radially and overlapped at their ends, said partitions being concentrically arranged and dividing the interior of the drum into several annular chambers and providing apertures for the flow of vapor from one annular chamber to the next, means connecting surfaceofanannularchamberandtransferring the liquid inwardly to the next inner chamber as the'drum rotates.

7. An evaporator as claimed in claim 6, wherein bailles are provided where one annular chamber communicates with another for the passage of vapor.

JAMIE EDWARD BIBBY.

DOES CITED- The following references are of record in the file of this patent:

the residual liquid discharge means in the evap- 35 UNITED PATENTS Placek Nov. 21, 1933

Images