US2556186A - Varying diameter vertical tube evaporator - Google Patents

Description

June 12, 195 F. HEGENBARTH VARYING DIAMETER VERTICAL TUBE EVAPORATOR 2 Sheets-Sheet 1 Filed Nov. 24, 1947 wmmmm June 12, 1951 HEGENBARTH 2,556,185

VARYING DIAMETER VERTICAL TUBE EVAPORATOR Filed Nov. 24, 1947 2 Sheets-Sheet 2 INVENTOR ATTORNEYS Patented June 12, 1 951 VARYING DIAMETER VERTICAL TUBE EVAPQRATOR Francis Hegenbarth, Wilkes-Barre, Pa.

Application November 24, 1947, Serial No. 787,668

3 Claims. (01. 15927) The present invention relates to improvements in varying diameter vertical tube evaporator and is applicable generally to sugar vacuum pans,

evaporators, calandrias, or other heat-exchange units for the concentration of solutions, for instance sugar or any other chemical solution.

An object of the invention is to provide an improved heat-exchange unit for use in such apparatus which will promote a more thorough and efiicient circulation of the sugar or other solution throughout the pan or other container to the end of promoting a more efiective and more expeditious evaporation.

The invention has for its further purpose to provide a heat-exchange unit for accomplishing the above described purposes which is simple in construction, involves no mechanical parts for the promulgation of circulation but uses in a general way the thermal eliect produced by the special arrangement of the vertical tubes.

With the foregoing and other objects in view, the invention will be more fully described hereinafter and more particularly pointed out in the appended claims.

In the drawings, in which like parts are denoted by the same reference characters throughout the several views,

Figure 1 is a vertical section taken through a form of vacuum pan and steam belt or calandria as constructed in accordance with the present invention;

Figure 2 is a top plan view with parts broken away and showing a part of the heating belt or calandria;

Figure 3 is an enlarged detailed vertical view taken through a portion of the steam belt or calandria;

Figure 4 is a vertical section taken through a form of calandria in which the bottom tube sheet is inclined and the tubes are of progressively shorter lengths toward the downtake; and

Figure 5 is a similar view showing both upper and lower tube sheets inclined in a convergent manner toward the .downtake with larger diameter tubes at the center of shorter length and progressing outwardly in length but in diminishing diameter toward the wrapper sheet.

I-Ieretofore in accordance with present practice a steam belt or calandria consists of top and bottom tube sheets I 0 and l B, respectively, a large central well 12, and a wrapper sheet l3 of the general diameter of the pan. One or more steam' inlets I4 is provided in the wrapper sheet is to admit steam or vapor to the interior of the calandria of this description, The top and bot-" cated at E5.

tom tube sheets l0 and II are provided with circular holes into which tubes 15 are expanded extending to the entire height of the calandria. The steam entering this calandria surrounds completely all the tubes contained in the calan: dria unit.

The vacuum pan usually consists of a spherical- 1y or conically shaped bottom it upon which rests the calandria, and upon the calandria is placed a cylindrical hollow part called the liquor belt or vapor belt IT.

A dome shaped top part I8 is provided having a separator l 9 to retain any carried over globules of the solution which will be drained back into the pan to avoid loss from entrainment.

Heretofore the vertical tubes I5 used in the calandria were usually made of equal diameter. It is a fact that the diameter of the tubes is in the inverse ratio to the velocity with which the solution flows through the inside of the tubes, which inside constitutes the surface transferring heat from the heating steam in the calandria to the solution boiled in the vacuum pan. There-. fore a smaller tube will induce the solution to flow at a higher speed through the tube than a tube of larger diameter will .do. As a consequence, the solution will be ejected from the tube at the level of the upper tube sheet with much greater force than through larger tubes. I use an arrangement of such heating tubes in the calandria in several concentric zones around the center downtake in which the outermost concentric zone contains the tubes of smallest diameter, gradually augmented in diameter as they approach the center downtake. The smallest tubes 15* are shown in an outer zone. For illustration and ex-j ample purposes, a second zone of progressively. larger diameter tubes is shown at [5 and a third inner zone of still larger diameter tubes is indi-.

While for the purpose of demonstration we have here selectedthree zones, it will be depending mostly upon the diameter of the vacuum pan how many zones shall beactually employed for the best results. A greater or lesser number of zones or tube diameters may be employed. An arrangement as just described will result in an induced circulation of the boiling liquid in the pan in the sense that the most rapid circulation will be through the smaller tubes l5=* nearest the periphery of the pan, while the circu'-.. lation velocity will be gradually reduced toward; the center of the pan as tubes of larger diameter are used in zones approaching the center down-,1 take. It will be seen that by this means a definitepredetermined circulation of the boiling liquid will have to take place from the periphery of the pan towards the center downtake, which constitutes the coolest part of the calandria. The solution will descend through the center downtake into the bottom from where it will re-ascend in the vertical tubes of the calandria. By the means indicated the use of mechanical apparatus for inducing such circulation will be entirely omitted.

Heretofore. in the-art, vertical or, inclined tubes in a calandria'were employed, of equal diameter and length, and expanded at their ends into horizontal or inclined tube sheets. The scope of my invention permits the use of either such horizontal parallel tube sheets or tubesheetsarrangQd with their planes at an angle to the horizontal plane of the calandria, as shown in alternate ,arrangements on Figure 4 and Figure 5. Such arrangements permit the useof the smallestdiameter tubes to be of the relatively greatest length and the progressively relatively larger tubes ,of progressively lesser length, -the largest diameter tubes adjoining the center downtake, beingof the relatively shortest length. .Thisarrangement assures the ,most violent upon circulation in the longest tubes of relativelysmallest .diameter with the velocity of circulation diniinishing in the tubesplaced. in zones approaching the centerdowntake in proportion to the relative diameters and lengths of the tubes in.the.various zones andsothat the minimum of circulation will occur in the zone nearest the downtake. It is .evidentthat the arrangement shown on Figure 4 can also bemade with only, the lower tube. sheet atithe incline shown, with the upper. tube sheet in a horizontal position. Inthe art the bottom parts l6, are usually carried out in a streamline shape as'indicated to avoidany large volumeof the boiling mass in aninert-or stagnant condition withinthe bottom.

The velocity ofthe flow of solution through the tubesrdepends on the diameter of .the tube and thelength of same. .The smaller in diameter and lqngersuchheating,tube is the more-violent the rifiingefiect of the discharge and thegreaterthe height to which. the liquid is proiectedorelevated abovethetop tube sheet. It is. evident therefore thatthense of small diameter tubes at the periphery and gradually larger sized diameter tubes towardsthe centerdowntake .orwell, all beingof thesame length, will produce exactly;the effeet required for .theideal circulation promoting the highesteificiencyof heat trarsferand evaporation resulting therefrom.

1 It is customary intheart to provide meansfor the removal of incondensible gases from the steam space and for this purpose the-customary provisionswill-be made. The same. applies to the removaloi condensate-resulting from ,thebondensationpf steam, during the process ofheating, which will haveto be evacuated rapidly in order not to cover and insulate effective rheating surfaces.

On'the drawings wehave indicated diagrammatically by the use ofarrows '20, Hand 22 the comparative height to which the-solution is.projected from the tubes I 5*, i5 and 15 respectively. 'It will be seen that the arrowsiilascend to the highest elevation while the arrows 2! of the intermediate zone tubes l'fi ascend to a lesser elevationand the arrows .22 of the largest diam eter tubes I 5 in the central zone ascend-to a still lower elevation. Consequently the solution .as projected from the innermost tubes 5 willnot interfere with the loop of the circulatorysystem of the intermediate tubes as indicated by the err-- scentof'those currents through the downtake of rows 2| nor with the circulatory system of the outermost tubes [5 as indicated by the arrows 20. In other words the loops or cycles of the thermal currents of the several zones will take place independently and the larger circulatory loops respectively from the outer zone to the inner zone and the horizontal transfer of the material from the topmost projected movement toward the center of the calandria prior to descent toward the :central well or downtake wil1 take place smoothly without mutually interfering.

*While there are independent currents issuing from the various respective zones, any difference indensity or temperature is made impossible from the intimate mixture occurring during the dethe pan thus resulting in a fully homogeneous nature of the boiling mass.

-Whi-le the above represents one mode of construction of such a vacuum pan with the improved calandria, it -merely represents the type mostcommonly used in the art but anysimilar or equivalent construction or design will be covered by..the invention.

Wh'i1e.I-have disclosed herein the best form of the invention known to me at the present time, I desirelit to be understood that I reserve the right to. makechanges and modifications in the herein described embodiment of the invention provided such changes fall within the scope of the following. claims.

"'What I claim is:

1. In a vacuum pan, a steam belt or calandria Comprising an outer wrapper sheet having a steam inlet, top and bottom tubesheets, a central downtake, and tubes ofvarying diameters having theirendsexpanded into said top and'bottom tube sheets, said tubes arranged in substantially concentric zones between the downtake and the wrapper sheet with the larger diameter tubes in the central zones immediately adjoining the downtake and the smaller diametertubes in the outermost zone adjoining the wrapper sheet and with intermediate sized diameter tubes in zones between said innerand outer zones.

2. :In a vacuum pan, asteam belt or.:calandria comprising an outer wrapper sheet rhav'ing a steam .in1et,'topand bottom tube sheets, acentral downtake, and tubes of varying diameters and lengths, having their ends expanded into said top and bottom tube sheets, said tubes arranged in substantially: concentric zones between thedowntake and thewrapper sheet, with the relatively larger diameter and shorter tubes in thecentral zone immediately adjoining the downtake .and the relativelysmallest diameter andI]ongest tubes in the outermost zones adjoining the :wrapper sheet and-with intermediate size tubes in zones between'the said innermost and outermost zones.

3. Ina vacuum pan, a steam belt or calandria comprising an outer wrapper sheet having steam inlets,top and'bottom tube sheetaa central downtake, and tubes of varying diameters having their ends extended through said tube sheets, said tube sheets, being apart from one another by the length of said tubes, said central downtake extending partially beyond the bottom tube sheet. said tubes arranged in substantially concentric zones'between said downtake andsaid wrapper sheet with the larger diameter tubes bordering the'periphery of said downtake :and the smaller diameter tubes in the outermost zone adjacent said wrappersheet and intermediate sized diarreter tubes inconcentric zones between said larger andsrnaller diametertubes, said tubes beingar- 5 ranged with their diameter increasing from the Number wrapper sheet inwardly to the central downtake. 1,558,957 FRANCIS HEGENBARTH. 1,853,739 2,065,147 REFERENCES CITED 5 The following references are of record in the N b file of this patent: 5 UNITED STATES PATENTS 58:037 Number Name Date 10 73,305 1,168,758 Stade Jan. 18, 1916 26,336 1,385,499 Schwarz July 26, 1921 204,845

Name Date White Oct. 2'7, 1925 Montgomery Apr. 12, 1932 Munson Dec. 22, 1936 FOREIGN PATENTS Country Date Germany Oct. 4, 1880 Germany Aug. 7, 1891 Germany Jan. 7, 1894 Great Britain 1902 Germany Dec. 7, 1908

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