US1793174A - Evaporator - Google Patents

Description

Feb. 17, 1931.

F. HOFMEISTER ET AL EVAPORATOR Filed Dec. 3, 1928 3 Sheets-Sheet l Feb. 17, 1931.

F. HoFMr-:lsTER ETAL i 1,793,174

EVAPORATOR Filed Dec; 3, 1928 3 sheets-sheen si Patented Feb. 17, 1931 `UNI'I'IID` STATES PATENT OFFICE i' FRANZ HOFMEISTER, 0F SCHLESISCH-OSTBAU, CZECHSLOVAKIA, AND HANS HEL- HARDT, F VIENNA, AUSTRIA, 'ASSIGNORS T0 CHEMISCHE FABRIKEN J. BELLAK,'

OF. VIENNA, AUSTRIA, A FIRM 0F AUSTRIA avaromroa Application med December 3, 1928; Serial No. 323,420, and in Austria January lo, 1927.

This invention relates to evaporators, par- -y ticularly such as are employed for evaporating and concentrating liquids and of the type comprising steam heated tubes, on which the liquid to be concentrated is caused to drizzle down. y

In the known apparatus of this kind evaporating tubes of equal diameters are uniformly distributed all over the space of the evaporating chamber through which the liquid has to pass and the liquid drips on them from a distributing device placed at the top of the said chamber. The evaporating surface of the single tubes is constant, while on the other hand the amount of liquid drizzling down on them is'varying, as the liquid on the way down is progressively concentrated. If for instance the liquid ought to be concentrated in the evaporator. to a quarter of its initial quantity or' volume, only a quarter of the quantity of liquid delivered to the highest horizontal layer of tubes will arrive.

at the lowest row. Under these circumstances the evaporating capacity of the tubes is not completely utilized for the reason, that the lowest tubes receive considerably less liquid than they should becapable of vaporizing, while, on the other hand, the liquid coming in contact with the tubes of the highest horizontal row exceeds the eective range of the latter. l

An object of our' present invention is to do away with this drawback and to provide an arrangement, by which the vaporizing capacity of all the tubes is uniformly utilized to its full extent which arrangement can of course only consist in that the heating surface successively reached by a determined initial and successively decreasing amount of liquid decreases from top to bottom. Such decrease can of course be effected in any manner preferred by the expert constructor, for instance in such manner, that the number of tubes of one single horizontal tube row decreases from the highest row downward.

A feature ofthe known arrangements of the evaporating tubes consists in this, that the tubes of one'horizontal layer are in staggered relation withrespect to the pipes of adjacent layers, that is to say of the one above and the one underneath it. The intended eiect of this known arrangement is to obtain, that the liquid spattering off from one pipe 1s caught up by the staggered pipes of the following layer, but in fact this result is realized only in the upper layers of tubes, where the amount of liquid attaining each tube is relatively large. At the lower layers much less liquid arrives, the quantity being so little, that the entire liquid arriving there is held on the surface of the tube by adhesion in form "of a thin film and no drizzling takes place any more. Consequently of the lowest layer every second tube recelves nearly no liquid atallj.

Also this vinconvenience is in the apparatus according to our invention avoided by a special arrangement of the pipes.

Furthery objects and advantages of our apparatus will be set forth with reference to the drawings, in which, by wayof example an embodiment of our invention is illustrated.l

Fig'. 1 shows a front elevation of an evaporator `comprising several evaporating chambers or elements, the front wall of the middle elementnbeing taken oil",

Fig. 2 a side view of an element, partly sectional,

Fig. 3 a plan view of the-entire apparatus,

Fig. 4 a sectional view of the feeding devlce and of an evaporating tube at an en-l larged scale, v

Fig. 5 a section through the feeding device by the line V-V of Fig. 4,` i Y Fig. 6 a sectionalview according to line 6-6 of Fig. 4,

Fig. 7 a sectional view of a collecting vessel (receiver) and A Fig. 8 a modified formof the latter.

In the case as shown, the entire apparatus comprises three evaporating elements 1, 2,3 constructed all alike. 4 indicates theevaporating chamber properly spoken, which forl manufacturing conveniences is made of several arts or sections. Inv theevaporatin cham er the heating tubes 5 are 'place which extend through the front wall Gand the rear wall 7 o f the element. In each hori-l zontal row of tubes of the up ersection there are four tubes, in eachA r'ow o the middle secg tical row of tubes beneath it.

tion two tubes and in the lower section there is only one vertical row of tubes. The heating tubes are arranged vertically above each other and are in both walls mounted so as to be easily interchangeable.

To the front end of each tube a socket 8 is secured by welding and at the rear end a cap 9 is put on under tightening pressure. Between a flange 10 of the socket 8 and a tapered edge of the opening 11 provided in the front wall 6 an annular gasket 12 is interposed, the tightening of which is obtained by pressing the socket 8 against the wall 6 by means of arms 13 engaging with a second flange of the socket. The arms 13 turn on screw-bolts 14 and can be pressed against the outer flange of the socket by the screw nuts 15.

The front end of the socket contains a four armed cross 16 into the boss of which afbolt 17 is screwed carrying a valve 18, by which the ingress openingl of the socket can be throttled to any convenient extent by adjust-- ing the position of the bolt 17 accordingly.

The cap 9 at the rear end of each tube is tightened by an annular gasket 19 and provided in its highest part with an outlet 20 for the escape of noncondensable gases and vapors and on its lowest part with an outlet 21 for-the water resulting from condensation. The sectional area of the outlet 20 can be varied by means of the adjustable valve 22 and that of the outlet 21 by a turning slide valve 23, the window 24 of which is brought to coincide more or less with the opening 21. The means for keeping the cap 9 in tightening position are not shown. They may be the same as used for keeping the socket 8 in tightening position. A

Between the last tubes of one group or section having the same number of tubes in one horizontal row and the highest tubes of the next group a collecting vessel 25 (Fig. 7) or 26 Fig. 8) is inserted, which collects the liquid drizzling down from two or more vertical tube rows and lets it run down on a ver- These collect-l ing vessels have the form of pans, the bottom of which has a slotlike outlet 27 extending parallel to the tubes 5. The front and rear -walls of these collecting pans are provided with circular holes which permit th\e pansm t0 be simply hung up on the tubes by shifting them thereon. Thus y the pans may, as is shown in the middle section of the middle element of Fig. 1 be placed higher or lower as required. i

Above the highesthorizontal row of tubes the feeding device is placed. It consists of tubes 28 arranged parallel to the evaporating tubes, each of the latter being provided with a longitudinal slot 29, in which a rail or bar 30 of double wedged section is placed. The liquid when flowing out from the slot 29 runs along the tapered sides of the bar 30 f and from the lower edge of the latter falls down in the form of a thin layer or film of liquid. For regulating the quantity of the liqpid to be delivered to the evaporating tu es the position of the wedged bar 30 is adjustable in vertical direction, the adjustment being effected by turninfr a shaft 3l, 0n the excentric part'32 of whiclh an arm 33 is pending. To the bolt 34 of this arm a fork is connected, which carriesthe bar 30 and by means of the shaft 31 and' the tube 28 is guided so as to move in a straight way only. The tubes 28 are closed on one end and on the other branching ofi from transversal tubes 36, which are fed from a manifold or supply pipe common to all elements.

Adjacent to the walls 6 and 7 of the evaporation chamber there are chambers 37 and 38, the tubes 5 communicating at their front ends with the chamber 37 and at their rear end with the chamber 38. .From the chamber 37 steam is supplied'into the tubes 5. The

chamber 37 of t-he first element communii cates by a pipe 39 with the main pipe supplying the live steam, the chamber 37 of the second element by a pipe 40 with the evaporating chamber of the first element, the chamber 37 of the third element by a pipe 41 with the evaporating chamber of the second element. To the cvaporating chamber o'tthe third element a condenser is connected by means of a pipe .42. To the upper part of the chambers 38 of all elements a suction duct is connected for sucking ott' the noncoudensable gases and vapors and to their lower part a pipe, in which the water resulting from condensation is collected. From the bottom of each evaporating element al duct 43leads to a receptacle 44, from which the concentrated liquid is drawn off at intervals.

When the apparatus is operated, the same amount of liquid to be concentrated iows to the tubes 28 of all three elements. In the first element the evaporation is effected by the live steam passing through the tubes 5, in the second element by the vapors coming from the evaporation chamber of the first element and in the third element by the vapors escaping from the evaporating chamber of the second element. As the pressure decreases within the eva-porating chambers of the consecutive elements, the evaporation in the subsequent elements sets in at lower tcmperatures, so that the total amount of heat to jim be imparted to the liquid under treatment is less than in the case ofthe elements being connected in series with respect of the supply of liquid to each element. Under these conditions also the height of the entire appa-v tion of the heating surface of the tubes. Also the fact, thatthe condensate and the vapors are iowing in the same direction, is of importance for obtaining high etliciency.

The sectionalA area of the opening 21,

-through which the condensate escapes, is adas to suit its vaporizing capacity, a perfect utilization of the heat is thus realized.

If in operating the apparatus it should occur, that the evaporation at the place where the collecting pan 25 is put, has not proceeded to such degree as re ulred, and if this cannot be remedied by a justing the valves 18 on the evaporating tubes nor by altering the position of the wedged bars 30 on the supply pipes the collecting pan 25 must be placed deeper for example in the .position 25.

What we claim is:

1. An evaporator with steam heated tubes, on which the liquid to be concentrated is drizzling', in which evaporator the heating surface reached by a determined initial and successively decreasing amount of liquid is decreasing from top to bottom.

2. 'An evaporator with steam heated tubes of equal diameter, onwhich theliquid to be concentrated is drizzling, in which evaporator horizontal rows of tubes containing each equal numbers .thereof are vunited to form groups and the number' of tubes in the horizontal rows of each group is decreasing from the top to the bottom. 3. An evaporator comprising steam heated `tubes drizzled on'by the liquid-to be concentrated and arranged in horizontal rows, the tube number of which rows decreases by groups from the top downward, and collecting rece tacles placed between adjacent groups, w ich receptacles are adapted to take up the liquid drizzling oi from several vertical rows o-.tubes and to lead it through an outlet to a vertical row of tubes.

4. ,An evaporator comprising steam heated tubesdrizzled" on bythe liquidto be concentrated and arranged in horizontal rows,

the tube number of which rows decreases by groups from the to downward, and collecting receptacles p aced between adjacent` groups, which receptacles are adapted to take `up the liquid drizzling oft' from several vertical rows of tubes and to lead it through an outlet provided in their bottom to a vertical row of tubes.

5. In an evaporator the combination of an evaporating chamber traversed by tubes, in the upper part or which chamber means for distributing the liquid to be concentrated are provided, steam admission chambers, witbwhich the evaporatng tubes are communicating at their front ends, and of vacuum chambers communicating with the evaporating tubes at their rear end, each of which rear ends is in its upper part provided with an outlet for the noncondensa le gases and vapors and on its lower part with 'an outlet for the water resulting from condensation.

In testimony whereof we have signed our names to this specification.

' FRANZ 'HOFMEISTER HANS MELHARDT.

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