US2349657A - Tubular film evaporating apparatus - Google Patents

Description

May 239 1944. c. M. A. HERMELIN TUBULAR FILM EVAPORTING APPARATUS Filed Oct. 25, 1940 INVENToR.

c v B Patented May 23, 1944 t 2,349,657 l TUBULAR. FILM EVAPORATING APPARATUS Carl Maximilian Axel Hermelin, Ulvsunda, Stuckholm, Sweden, assgnor to Aktiebolaget Rosenblads Patents, Stockholm, Sweden Application October 25, 1940, Serial No. 362,761

In Sweden c tober 26, 1939 4 Claims.` (Cl. 159-13) The invention refers to tubular film evaporating apparatus and more particularly to such apparatus of the type which comprises a plurality of vertical heating tubes arranged within a com mon evaporating chamber so as to receive the liquid to be evaporated in the form of a film on their outer surfaces, while being heated by any suitable heating medium which is introduced into the tubes.

It is an object of the invention to so arrange the heating tubes in apparatus of the character described that they are freely expandable at their upper ends in the axial direction, in order to eliminate undue stresses on-account of varying temperature conditions.

Another object of the invention is to provide means for radially guiding the heating tubes at the upper tube ends so that they are kept in the correct vertical position without axial expansion being prevented.

Still another object of the invention is to provide liquid distributing means for feeding the liquid to bel evaporated onto the outer surfaces of the heating tubes at the upper ends of the latter so as to cause the liquid to flow down over the tubes in a proper film formation, and constructing the liquid distributing means so that they may also serve as guiding means for the upper ends of the tubes.

A further object of the invention is to prevent the upper end portions of the heating tubes, which rst receive the liquid, from being heated by the heating medium in order to prevent scale formation which would interfere with the formation of the liquid film.

Various further objects of the invention will be apparent from the following description describing more in de'tail an embodiment of the invention and some modiiications of certain features thereof, as shown in the accompanying drawing of which;

Fig. 1 is a vertical section through an evaporating apparatus according to the invention;

Fig. 2 is a vertical section through certain portions of such apparatus, illustrating'on an enlarged scale the upper end of a heating tube with combined liquid distributing and guiding means for the same, all of a similar design as in Fig. 1;

Fig. 3 is a Vertical section through the corresponding parts of another embodiment thereof; i,

Fig.` 4 is top A`View. of the embodiment shown in Fig. 3; and

Figs. 5 and 6 are vertical and cross sectional views, respectively, the latter taken on line 6--6 in the former,v of astill further modiiication. A

Referring now to Fig. 1` of the drawing, the evaporating apparatus as here shown includes a substantially cylindrical vertically disposed casing, consisting of three joined parts of which the central one, designated by reference character l forms an evaporating chamber. The evaporating chamber is separated by horizontal plates 2 and 3, respectively, from an upper and a lower chamber formed by the parts Iaand lo of the casing and their end covers. The liquid which is to be evaporated is supplied to the upper chamber through the inlet 4 and removed from the evaporating chamber through the outlet 5, While the vapours generated therein escape through the outlet 6. To the lower chamber there is supplied a heating medium, preferably steam, through the inlet 1 and the condensate is discharged therefrom, through the outlet 8.

In the evaporating chamber there are inserted a plurality of heating tubes I0 which at their lower ends are iixed to the lower plate 3 and communicate therethrough with the lower chamber so that the heating medium has access to the interior of the heating tubes. The upper ends of the heating tubes l0 terminate somewhat below the upper plate 2 and are closed by means ci end pieces Il whereby there is defined a separate top space within the end portion of each tube, said top space being partitioned from the tube channel proper, while being open upwards. Further, the upper plate 2 is designed to serve as liquid distributing means and for that purpose it is provided with small supply pipes i2 or the like, each of which is arranged to project downwards in coaxial relationship with a corresponding heating tube and into the top space of the same so as to feed liquid into that top space.

A similar arrangement of liquid distributing means is more clearly shown in Fig. 2, wherein 2a indicates the upper plate of the evaporating chamber and 12a one supply pipe of said plate i'or the heating tube I0 which has a somewhat modified end piece Ila in the form of a cylinder with one end closed, being fitted into the heating tube with the closed end forming an inside partition and welded to the former at the juxtaposed free terminal edges of both. The supply pipe Ita, which projects into the separate top space of the heating tube, as formed by the end piece I la, has disposed Within the latter radially outwards extending wing-like guiding means I3a., the outer vertical edges of which approximately coincide with the vertical inner surface of said top space so that the heating tube is kept in the correct vertical position without preventing axial eXpansion of the otherwise entirely free upper end.

Since the top space of the heating tubes I ll will be filled with liquid and any evaporation therein should be avoided, as this might result in scale formation which would be apt to obstruct the supply of liquid, it is most advisable to provide means for preventing heat transmission to said space from the heating medium in the heating tube. For this purpose either the walls of the top space referred to may be insulated by a layer of some suitable non-heat-conducting material, at least at the bottom, as indicated at III in Fig. l, or as shown in Fig. 2, there may be inserted an additional partition wall I4 in vthe heating tube a short distance beneath the upper end piece IIa so as to form an insulating space under the same.

The evaporating apparatus described works` substantially as follows: The liquid which is'to be evaporated enters through the inlet 4 into the upper chamber` of the .apparatus where it will stand therein toa certain level over the plate 2. From here it is delivered by the pipes I2 into the top space of the corresponding heating tubes Ii]v and then caused .to flow over the upper edges thereof so that it will pass downwards along the outside tube surfaces in the form of a lm. Finally, any position of liquid remaining unevaporated at the lower ends of Athe heating tubes is collected at the bottom of the evaporating chamber above the plate 3 and is withdrawn therefrom through the outlet 5. During the passage of the liquid alone the heating tubes, evaporation takes place due to heat transfer through the tube g .g

walls from the heating medium supplied to the tube channels through the inlet 7 to the lower chamber. from the evaporating chambei` through the outlet 6. I

It is an important advantage of this type -of apparatus that the vapours are readily separated from the liquid, practically at the same rplace and moment as generated and therefore over the greatest possible surface while at a relatively low velocity, so that normally no inadmissible great quantity of liquid will be carried away -by the vapours which would require additional separating means.

According to Fig. 3 the guiding means for the heating tubes I Ican be replaced by a plate 2b with supply openings I2b which are suitably circular in cross section and located directly above the respective heating tubes. In this case the end piece IIb of the heating tubes is made plug-like, as here shown, or possibly cap-like in shape and is removably attached to the upper tube end so as to close the same. The end piece I Ib should preferablyform an outward conical cover for the tube terminal, and is provided withI a centrally disposed rodlike member which projects vertically upwards. This rod-like member, which is coairial with the heating tube, fits into the corresponding supply opening IZb of the plate `2b but has such a cross section, cross-shaped, for instance, that it engages only comparatively small portions of the periphery of the opening. Moreover, the 'arrangement is such that a suicient area of the opening is left unobstructed for the passage of liquid which will thus bev spread over the end piece of the heating tube and caused to flow down over the outside tube surface in film formation. By virtue of this arrangement the heating tube I is free to expand and contract in axial direcliquid distributing and The vapours thus generated escape tion while being kept in the correct vertical position by the rod-like member of the end piece IIb which is guided in the opening I2b.

As shown by Figs. 5 and 6 a further possible modification of the liquid distributing and guiding means for the heating tubes consist in having the heating tubes I0, which in this case have the upper ends closed by an end piece I Ic welded to the terminal edges of the tube, arranged to project through corresponding supply openings IZc in the plate 2c. The diameter of the openings I2c is somewhat greater than that of the heating tube so that an annular slot for the passage of the liquid is formed around the same, and thus the liquid is caused to now down over the outside tube surface in nlm formation, but at some points, however, the periphery of the opening provides guiding surfaces for the heating tube I0 in the form of small radial projections I3c adapted to engage the tube surface so that the tube is kept in the `correct vertical position, while being free to expand and contract vertically.

Naturally a great many other changes fall Within the scope of the invention and it is under.- stood that the invention is not limited otherwise than by the` appended claims.

. Thus, what I claim as new and desire to secure by Letters Patent is:

1. In an evaporating apparatus, a tubular member providing an exterior evaporating surface, means rigidly secured to the lower part of said member for supporting it in a vertical position, means for introducing a heating medium into the lower end of said member, an end wall disposed in said tubular member a short distance below its upper end to thereby provide a space within the upper end open at the top, a rigidly supported liquid supply pipe terminating in said space, the outer diameter of said pipe being less than the inner diameter of said space, and riblike members extending radially from said pipe and slidably engaging the inner sides of said space to maintain said tubular member in a vertical position while permitting vertical expansion and contraction thereof.

2. In an evaporating apparatus, a tubular member providing an exterior evaporating surface, means rigidly secured to the lower part of said member for supporting it in a vertical position, means for introducing a heating medium into the lower end of said member, a liquid distributing plate disposed above said tubular member and having van opening in alignment with the axis of the member; an end piece for closing the upper end of said tubular member, and a rodlike member extending upwardly from said end piece and into said opening, the cross-sectional configurations of said rod-like member and said opening being such that the former slidingly contacts the side of the latter at spaced points to maintain said tubular member in a vertical position while permitting expansion and contraction thereof, and is spaced from the side of said opening at other points to provide for ow of liquid therethrough.v

3. In an evaporating apparatus, a substantially horizon-tal liquid distributing plate member formed with an opening therethrough, a tubular member providing an exterior evaporating surface, means forclosing the upper end of said tubular member, means rigidly secured to the lower part of said tubular member for supporting it in a vertical position with the closed upper end thereof. directly below said opening, means for introducing a vheating medium into the lower end of said tubular member, and an outwardly flanged rigid element associated with the upper end of said tubular member and extending into said opening for guiding liquid flowing through said opening to the exterior of said tubular member, said rigid element being fixed to one of said members and the flanges thereof being in Vertically slidable Contact with the other of said members to thereby maintain the upper end of said tubular member in alignment with the opening in said plate member while permitting Vertical expansion and contraction of said tubular member with respect to said plate member and permitting flow of fluid between the exterior of said element and said other of said members.

4. In an evaporating apparatus, a substantially horizontal liquid distributing plate member formed with an opening therethrough, a tubular member providing an exterior evaporating surface, means rigidly secured to the lower part of said tubular member for supporting it in a Vertical position directly below said opening, means for introducing a heating medium into the lower end of said tubular member, means for closing said tubular member a short distance below its upper end whereby the heating medium is prevented from flowing to the extreme upper end of the tubular member, and an outwardly flanged rigid element associated with the upper end of said tubular member and extending into said opening for guiding liquid flowing through said opening to the exterior of said tubular member, said rigid element being fixed to one of said members and the anges thereof being in vertically slidable' Contact with the other of said members to thereby maintain the upper end of said tubular member in alignment with the opening in said plate member while permitting vertical expansion and contraction of said tubular member with respect to said plate member while permitting ow of fluid between the exterior of said element and said other of said members.

CARL MAXIMILIAN AXEL HERMELIN.

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