US2676651A - Evaporating apparatus - Google Patents

Description

pril 27, 1954 J. LOUMIET ET LAVIGNE 2,676,651

EVAPORATING APPARATUS Filed May 16, 1945 e Shee ts-Sheet 1 grime/WM JEAN ZUUM/ET ET LflV/G/VE April 27, 1954 J. LOUMIET ET LAVIGNE 2,676,651

EVAPORATING APPARATUS Filed May 16, 1945 6 Sheets-Sheet 2 J wue/wbo v JEAN -LOUM/ET 'ET LAM/6N5 April 27, 1954 Filed May 16, 1945 J. LOUMIET ET LAVlGNE EVAPORATING APPARATUS 6 Sheets-Sheet 3 April 7, 1954 .1. LOUMIET ET LAVIGNE 2,676,651

EVAPORATING APPARATUS Filed May 16, 1945 6 Sheets-Sheet 4 jwumvbm JEAN LOUM/ET ET LAV/GNE Api'i 7, 1954 J. LOUMIET ET 'LAVIG-NE 7 EVAPORATING APPARATUS 6 Sheets-Sheet 5 Filed May 16, 1945 JEAN LOUM/ET ET [AV/GIVE M an -2 Sum/M4 0 April 27, 1954 J. LOUMIET ET LAVIGNE 2,676,651

EVAPORATING APPARATUS 6 Sheets-Sheet 6 Filed May 16, 1945 JEAN LOUM/ET' 7 LAW/6N5 Patented Apr. 27, 1954 UNITED STATES PATENT OFFICE EVAPORATING APPARATUS Jean Loumiet et Lavigne, Itabo, Cuba Application May 16, 1945, Serial No. 594,031

Claims priority, application Cuba May 25, 1944 4 Claims.

'This invention relates to evaporating apparatus and more particularly to apparatus of multiple effects used for concentrating solutions by the evaporation of their solvents, as is done with sugar solutions in the manufacture of sugar. It is known that those apparatus comprise various units operating at pressures progressively lower and successively run over by the operated liquid from the unit of highest pressure to the unit of lowest pressure, wherein the product vapors of any unit except the unit of lowest pressure are applied as heating agent in the immediate unit of lower pressure.

It is an object of the invention to provide a unit comprising a lower evaporating calandria constituting an emulsifier of the operated liquid and mounted on the top of that emulsifier a main calandria in which the operated liquid penetrates at its outlet from the lower calandria emulsified with a great amount of steam, whereby the evaporating capacity of said main calandria is considerably increased.

It is a second object of the invention to provide means for emulsifying the operated liquid at the inlet of every one of the tubes of the lower calandria by virtue of a steam injection from an outside source.

It is another object of the invention to provide a unit of the type described in the preceding paragraph, comprising complementarily a heater surrounding the emulsifier and arranged within to cause the liquid being passed therethrough to take a circuitous path whereby the liquid will be brought to a temperature near to the normal operating temperature of the emulsifier before the liquid is passed to the emulsifier proper.

It is still another object of the invention to provide appropriate diaphragms both in the calandrias of the evaporating units and in the complementary heaters in order to transform those calandrias into a circuit run over by the heating fluid, wherein the cross section of that fluid clecreases progressively in order to maintain a sumcient fluid speed.

It is a well known fact that the efiiciency of heat transfer from the steam in a calandria jacket to the liquid contained in the calandria tubes is greatly increased by the presence in the liquid of a substantial quantity of steam. The steam within the tubes tends to form a central core which forces the liquid in a thinned out manner against the tube walls. This is known in the art as climbing film effect.

' In prior evaporators, however, no provision has been made to assure the realization of the climbiii) ing film effect from end to end of the tubes of a calandria. There is generally some reduction of pressure of the liquid as it enters or approaches the tubes, which causes the liquid to reach the tubes in a super-heated condition. It might be supposed that this would immediately result in the spontaneous generation and release of an ample quantity of steam within the tubes but, in point of fact, the release of steam is uncertain and inadequate under actual operating conditions, so that the climbing film effect is likely not to be effectively realized until after the liquid has progressed a considerable distance upward along the tubes. This results in a loss of heating efficiency.

In order to overcome this deficiency there is provided, in accordance with the present invention, in connection with the evaporating calandria of each eifect or unit, a comparatively small auxiliary or emulsifying calandria through which the liquid en route to the main calandria is first passed in order that the liquid arriving at the tubes of the main calandria shall be thoroughly emulsified with steam generated within the tubes of the emulsifying calandria.

The number of tubes in the emulsifying calandria may be comparatively small as compared with the main calandria, because the volume of the combined liquid and steam is greatly increased in the passage through the lower calandria tubes, and is again greatly increased in the passage through the upper calandria tubes. By providing fewer tubes in the lower calandria the velocity of the liquid and steam through the lower calandria is held within limits of the same order of magnitude as the velocity of the liquid and steam through the upper or main calandria tubes. I

It is desirable that emulsifying steam be injected from an' outside source at the entering ends of the emulsifying calandria tubes, in order that the climbing film effect may also be realized from beginning to end of the emulsifying calandria tubes. This may be achieved at a small expense of injected steam because of the comparatively small number of tubes in the emulsifying calandria.

The mixed liquid and steam which emerge from the lower calandria tubes enter a,closed, solid-walled steam-tight chamber, which extends from the discharge ends of the tubes of the lower calandria to the entering ends of the tubes of the upper calandria and which communicates exclusively with the upper and lower calandria tubes. The chamber is sealed off completely from communication with the steam jacket of the upper or main calandria, and is unrestrictedly open from end to end to provide direct and free communication between the tubes of the lower calandria and the tubes of the upper calandria, whereby the chamber inescapably confines all the liquid and the steam emerging from the tubes of the lower calandria and causes them in their entirety to be delivered together at substantially undirninished pressure and temperatures to the tubes of the upper calandria where they achieve a climbing film effect from end to end of the numerous upper calandria tubes. Means are provided for supplying both the upper and the lower calandria jackets with heating steam of pressure and temperature substantially higher than the pressure and temperature existing within the lower calandria tubes, in order to produce eflicient heat exchange through the tube walls of both calandrias.

For other objects and for a better understanding of the invention, reference may be had to' the following detailed description taken in connection with the accompanying drawing in which Fig. 1 is an elevational view of a unit embodying features of the present invention and comprising an annular heater.

Fig. 2 is a vertical sectional view of theunit illustrated in Fig. 1.

Figs. 3, 4 and 5 are respectively horizontal cross-sectional views of the emsulsifier and heater of the same unit and taken at stations 3-3, 4--4l, and 55, of Fig. 1.

Fig. 6 shows a development of the annular heater about the emulsifier of said unit, illustrating the directional flow of the heating vapor therethrough.

Fig. '7 is a vertical cross-sectional view of a unit which does not comprise an annular heater.

Figs. 8, 9 and 10 are horizontal cross-sectional views taken through the emulsifier at'stations 8-8, 99 and l|ll0 of Fig. '7.

Referring now particularly to Figs. 1 to 5, the unit represented includes an emulsifier (3E1 having an annular heater U and a central calandria CI having vertically-extending tubes Q and a main calandria M1 mounted on the emulsifier. The function of the annular heater U is to pro vide the initial heat to the solution while the function of the central calandria is to bring about the emulsion of the solution. The annular heater U is made inthe customary form, in groups of three tubes Q operating in parallel and the solution under treatment and on each pass up and down the heater-is'distributed among these three tubes. It is understood,- of course, that any number of these tubes can be used. A group of three tubes is contained in each of spaces Qs, Fig. 4, withinthe annular heater U. The heating vapor is passed through all'these spaces Qs successively in a manner hereinafter disclosed.

The solution being'treated circulates successively through all these groups of three tubes Q of the heater, alternately in one vertical direction through one group and then in the other vertical direction through another group. This effect is attainedby connecting two successive groups with end channels C in the lower and upper heads Di, Us. All of the channels C of each head are isolated from one another.

The solution being treated is thus circulated through all groups of tubes and all the channels of the lower and upper heads, entering through pipe GD, Fig. 5, and leaving through a space 6 to 4 enter into the bottom ends of the tubes Q, of the central calandria CI, Fig. 2, from a circular space I0 thereunder.

Closing the bottom of the circular space In is a nozzle Y with numerous spouts 1, respectively aligned with open bottom ends of tubes Q. The medium or vapor for treating the liquid enters the nozzle Y through the tube 3. and leaves the nozzle Y through the severalvertical spouts I and then upwardly in space In to the tubes Q.

In this manner, the solution which arrives at the upper part of said circular space In enters the tubes Q at the same time as the injected vapor used to emulsify it. Having heated the calandria in a manner to be later described, the injected vapor is augmented by the vapor produced by partial evaporation of the liquid being treated insidethe tubes Q themselves. In this manner, by the time the treated liquid reaches the bottom F of the main calandria, it has becomehighlyemulsified and conditioned to absorb thegreatest amount of heat.

With steam issuing from said spouts and into the bottom, open ends of the tubes Q, the steam will occupy the center of the tubes and the liquid being so treated is forced in a thinned out manner against the tube wall, whereby the liquid is more'readily heated by the heating fluid passing externally about the tubes. Accordingly, the amount of heat transmitted to the liquid is increased, and a more effective evaporating unit is provided.

Calandria and annular heater U are supplied with heating medium through pipes St and T1. The heating medium from T1 before going through annular heater U, Fig. 2, first passes through the central calandria CI by way of passageway a'which fans out'vertically as it approaches the central calandria space CI so as to distribute the vapor throughout the entire height of the calandria. Inclined walls V and V constitute the upper and lower sides of the passageway a. The vapor which comes through the passageway a is thus distributed throughout the entire height of the calandria, goes through the central calandria CI diametrically and leaves through passageway 17 at the opposite side thereof, Figs. 2, 4, 6.

The tubes Q inside the central calandria CI are distributed somewhat irregularly, Fig. 5, but arranged so that resistance to the passage of the heating medium or vapor through the calandria from its entrance up to its outlet, may be fairly much the same and so that whatever path that the vapor may take among the tubes, there is assurance that the movement of the vapor is fairly equally distributed throughout the entire calandria, thereby avoiding any dead area therein.

Upon arriving at b, the heating medium or vapor is divided into two currents, Fig. 6. One of these currents goes through the spaces Qs on the right, entering from b and passing to a space adjacent passageway a, and the other current goes through the spaces Qs on the left, from b and passing to a space adjacent the-passageway a.

Upon arrival in the last spaces on opposite sides of passageway a, the currents are united by entry through the openings 7 and g into spaces K0, Lu, above and below the inletpassageway a and walls V and V. The high openings f pass the noncondensable gases'and uncondensed vapor to the space K0 while the low openings 9 pass the condensed vaporor water. The non-condensable gases combined with the uncondensed vapor are removed from the space K0 through the tube K and the condensed water is removed from the lower space Lo through the tube L.

The small openings or apertures d1, d2, d3, d4, d5, d6, etc. and (1'1, da, (1'3, (1'4, (1'5, (1'6, etc. Fig. 6 are provided in the walls or partitions Pl between the respective several spaces Qs for the purpose of passing the fluid from one space to the other. The total area of the openings is greater for a wall at the points of movement where the amount of vapor being passed is greater and small at the points of movement as in the last spaces where the amount of vapor is less. In other words, movement of the vapor or heating medium from b to a, whether through the right spaces or the leftspaces, the vapor goes from one space to the next through limitedapertures whoes total section is decreased each time in proportion to the progress of the'condensation and in such a manner that its velocity is not excessive at the beginning of the passage nor too low at the end thereof.

Referring now particularly to Fig. 6, where the heater is represented in development, with the passageway b in the center. tubes Q of one space is represented by a single vertical tube Q contained between two vertical walls Pl, which separate the space from the adjacent spaces. Ds, D2, are angularly adjusted with respect to each other in an amount equal to half a channel or return passage C so as to connect two adjacent groups of tubes together. The channels C are rounded as shown and contain a meta1 cylinder J which directs the stream of the treated liquid in this passage from one group of tubes of one space to the group of tubes of the next space, so that the. movement of that stream is more or less circular within the channel and thus the possibility of pressure loss caused by change in direction of'flow of the liquid is inhibited. The various tubes Q, Q, are supported in and extend through upper and lower closure plates Ps and Pi at their respective opposite ends thereof. The plates are held in place by heads Ds and D2.

The vapor which goes from b to the spaces im-- mediately adjacent thereto, enters the first space through five apertures dn, dn in the first wall P2,. which separates b from that space. The next walls which separate the first spaces from A group of three I The upper and lower heads the second have five apertures did, d'io, arranged 1 in staggered relation to the five apertures in the first wall. Confining the description to the left side, the following two walls on that side have respectively four and three apertures d9, d8, staggered to one another. spectively, four openings d7, three openings dc; two openings 115, two openings d4, three openingsd3, two openings dz, one opening 11 and the final" wall, the openings f, g, as above described. A corresponding arrangement of apertures is provided in the walls at the opposite side of the heater.

The vapor paths are generally decreased in number within the successive spaces in passing from b to the spaces Ko', Lo. As a result of successive condensations the steam vapor is reduced to its non-condensable gases which are removed from said container through the tube K. It is to be remembered that the dimensions of the succ'essive apertures are not all equal, since it is preferable that they be adapted to the volume'of the vapor passing through them. The number of The next walls have, re.

apertures is determined by the necessity to avoid excess velocity of the vapor in the first spaces to prevent substantial pressure loss in that vapor, and also by the necessity to maintain suflicient velocity in that vapor at the end to get a transmission of heat to the heated tubes Q and removal of the non-condensable gases.

On the top head Ds is disposed the main calandria M1, Fig. 2. This is effected by means of a neck-shaped casting A carried on the top thereof and supporting the calandria bottom F. The neck casting A is secured to the top head Ds by a packing nut P.

The main calandria M1 includes a heater section Z, Fig. 2, containing a plurality of vertically extending pipes z in communication with basin F and the top of the main calandria, and through which the liquid being treated is passed. Neither the entrance of the heating vapor, nor the circulation of that vapor in the calandria, nor the outlet of its condensates and of the uncondensed residue are shown in the figure because the description of the two types of lower calandria and of the heater annexed to the first are sufficient for relating all the features of the invention.

heated by vapor other than that supplied by preceding main calandrias. For example, they may be heated by the vapor that heats the first unit.

In every unit or effect the lower, emulsifying calandria is made to contain only a few tubes so compared with the associated upper, main calandria of the same unit. This causes a greater evaporating space to be provided in the upper calandria, making it possible to transmit all the steam from the lower calandria tubes, along with the liquid, into the upper calandria tubes, without producing a detrimentally high velocity of the liquid and steam in the upper tubes as the steam content of the upper tubes goes on increasing. The really important amount of evaporation takes place in the numerous tubes of the upper calandria. The function of the emulsifying calandria is to produce enough steam for assuring that the liquid will reach the main calandria sufiiciently emulsified with steam to assure maximum eificiency of operation of the main calandria. For this purpose a comparatively small emulsifying calandria is adequate. A larger emulsifyin calandria would add to the cost of the apparatus and would produce no corresponding gain of efliciency.

The emulsified liquid passing up through the heater Z isdrained ofi through a central pipe B with a reducing fitting E therein and delivered treatment through a pipe G01.

In Figs. 7, 8, 9 and 10, the lower part 01 a unit having no annular heater is shown. That arrangement is adopted generally in the units of an evaporating apparatus other than the first, because the concentrated liquor of the preceding unit which feeds the succeeding unit is easily maintained in a superheated state and does not require the above described annular heater U of emulsifier CE, as the first unit of an evaporating apparatus of multiple eifect.

In order to bring about proper heating in these units, the vertical calandria is divided into four spaces by radial walls P'Z1, P'Zz, P'Za, P'k, having respectively, window openings d'l, d'z, etc. therein. .The horizontal sectional area of these spaces diminishes :in proportionyto the decrease in volume of the vaportwhich goes through them,

Fig. 9, so as tomaintain the velocity'of the vapor:

inside the calandria fairly constant.

Recovered vapor is brought from the main calandria of the precedingunit and is delivered to the emulsifier'inlet T. Within theemulsifier E, itpasses from the larger spaces, Fig.9, .to the'smaller space; Outlet pipes, not shown, corresponding to pipes K and L of the unit of Fig. 2, may be connected to the smaller space for taking off respectively the non-condensed gases or vapors and the water condensate.

The c'onnectionsof the emulsifier E to' its main calandria is only slightly diiferent in Fig. '7 than in Fig. 2. The neck casting A is supported upon flanged upper end of the emulsifier casting, and packing. nut P is used for connecting the supporting basin F thereto. Drain pipe B; extends down from the main calandria through the emulsifier E for deliveryto a pipe I have described what I believe to be the best embodiments of my invention. I do not wish, however, to be confined to the specific embodimentsshown, but what I desire to cover by Letters Patent'is set forth in the appended claims.

I claim:

1. In an evaporating unit, an emulsifier having" a vertical calandria with tubes therein through which fluid being treated is passed. an annular. heater surrounding the emulsifier calandria and. havinga plurality of verticallyex-tending" wall partitions to provide spaces for the passage of heating vapors therethrough, tubes extending respectively through the heater spaces, a head member having return passages at the upper and lower ends of the heater and tubes to'direct the how of'liquid being treated from the tube of one space to the tube of another space-thereby to cause a circuitous path for the liquid traversingthe heater, 2. fiuid'connection' between the outlet end of the heater and the calandria for directing the fluid from the heater space, the said wall partition openings varying in number in the respective wall partitions, and the opening of adjacent partitions staggered with respect to each othenthe larger number of openings'bei'ng in the walls nearer to thepart of the heater first receiving the heating vapors from the vertical calandria and the smaller number of openings being in the walls nearer the end of the heating paths, whereby the velocity of the heating medium is retained constant through-- outthe annular heater.

2.' A unit of evaporating apparatus comprising an upper calandria of parallel tubes and a lower calandria of parallel tubes having at one of its extremities a li uidsupply chamber in free and open communication with the inlet ends of the tubes of that calandria; at its other extremity a closedchar'nber located between the calandrias, said-chamberconnectingjthe'outlet ends of the tubes of the lower calandria'directly and freely with the lower en s of the tubes of the upper Gil calandria; the lower ca-landria containing-'a less number of tubes thanrtheupper, an annular heater surroundingthe lower calandria, said heater including a plurality of groups of vertical tubes, each of. these groupsconstituted by an equal number of tubes all of. the same diameter andof the same length, located at the same level and the same radial distance from the center of the lower calandria around that center; a plurality of closed channels in the upperend of the heater and a plurality of closed channelsin the lower end of the heater and in each of which arrive the outlet ends of a group of tubes and the inlet ends .of the following group, except a first channel where instead of outletends of an entering group there is provided the outlet of a pipe which introduces the relatively, cold liquid to be treated, and a lastchannel Where instead of inlet ends of a following group there is provided an opening placing that channel in communication withthe liquid supply chamber of the lower calandria, in order to constitute a long circuit run over by that liquid.

3. In a unit of evaporating apparatus having a calefa-ction chamber that'surrounds tubes for material to be heated, the arrangement that consists in dividing the calefaction chamber in sectors by means of vertical and radial'divisions, the successive divisions having openings so disaligned that the heating vapors are compelled to travel lengthwise of thesectors, except one ivision that occupies at all its height the whole vertical radial section cor -esponding to the chamber and is unprovided with openings; there being locatedin the sectors adjacent to'that division, respectively atzoneside and the'other of the same, the entrance of the heating fluid and the outlet of its residualvapors and gases in order to create a circuit run over by the'heating vapor from its cntrance'to its outlet, the crosssection of the vapcr'path being progressively decreased from sectorto sector in accordance with the diminution of volumeof' the fiuid which results from the condensation of the vapor flowingthrough the paths, by making the angular distance between successive divisions diminish from sector to sector according to the direction of the movement of the heating fluid;

4. A single unit ofievaporating apparatus comprising, in combination; an upper main calandria hich includessubstantially vertical liquid evaporating tubes and a heating steam jacket surrounding the tubes; a lower emulsifying calandria which includes liquid evaporating tubes, a heating steam jacket surrounding the last mentioned tubes, and a liquid supply chamber in communication with the inlet ends of the tubes:

aclosed,rso1idwalled steam-tight chamber e: tending: from the discharge ends of the tubesof 1 at substantially undiminished pressure and tem-' perature to. the tubes of. the uppercalandria:

and means supplying to both the lower and upper calandria jackets heating steam of pressure and temperature substantially higher than the pressure and temperature existing within the lower calandria tubes in order to produce efficient heat exchange through the tube walls of both calandrias; the tubes of the upper, main calandria being several times as numerous, at least, as the tubes of the lower, emulsifying calandria to provide a greater evaporating volume in the upper calandria; thereby achieving a climbingfilm eflect from end to end of the upper calandria tubes.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 1,013,091 Kestner Dec. 26, 1911 Number 15 Number Name Date Rusiecki Mar. 26, 1912 Dunn July 23, 1912 Trump Feb. 13, 1917 Griere Mar. 15, 1921 Lawrence Jan. 27, 1925 Vila July 6, 1926 Dodd. July 7, 1981 Maniscalo Nov. 6, 1934 Theiler June- 2, 1936 Munson et a1. Dec. 22, 1936 Hall Oct. 8, 1940 FOREIGN PATENTS Country Date Germany Feb. 1, 1932

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