US1265863A - Evaporator. - Google Patents

Description

W. G. ABBOTT, JR.

[VAPOR/Hoa. APPLICATION FIALED 1AN.13, |915.

1,265.863. Patented May14,1918.

j 2 SHEETS--SHEET I. j@ f i (A4 f o Y) l W. G. ABBOTT, JR.

EVAPORATOR, APPucATIoN FILED 1AN.13,19|5.

1,265,863. Patented May/14,1918.

2 SHEETS-SHEET 2.

WILLIAM G. ABBOTT, JR., OF WILTON, NEW HAMPSHIRE.

EvAPoRAToR.

Specification of Letters Patent.

Patented May 14, 1918.

Application mea January 1s, 1915. serial No. 1996.

To all whom it may concern.'

Be it known that I, WILLIAM G. -ABBo'rn Jr., a citizen of the United States, and resident of Wilt-on, in the county of Hillsborough and State of New Hampshire, have invented new and useful Improvements in Evaporators, of which the following is a specification.

This invention relates to an apparatus for evaporating liquids, and consists in improvements by which evaporation is more etliciently carried on than in apparatus heretofore known to me, and in which a tube or wall, slightly spaced from a heater element, forms a narrow space therebetween, which is open at top and bottom, and connes a thin body or layer of the liquid in contact with the heating element. The thin body of liquid so formed is raised rapidly in temperature to a condition of ebullition, and by reason of its lesser density than that of the surrounding liquid in the evaporating vessel, is forced rapidly upward through the confined space by the superior hydraulic head of the exterior liquor, the vapor passing out through the open top of the confined heating space while fresh liquor enters through the open bottom of said heating space, thus maintaining an active circulation upward through the confined space in contact with the heating element. Said body or layer of liquor is preferably as thin and film-like as is consistent with free and rapid circulation.

Steam is preferably employed for heating the heater element; and the steam also is kept in circulation, and preferably in a direction opposite to that of the liquor being evaporated.

With my apparatus a large capacity per square foot of heating surface is secured, and also a low average boiling tempera ture due to a low hydraulic head.

In its preferred form the invention comprises a steam circulating duct within the liquid space of the evaporator, and a tube or wall, surrounding the steam duct and spaced therefrom but slightly, so that between the steam duct and the surrounding tube there is formed a thin layer or body of the liquor, the space between the steam duct and the tube being open at both top and bottom to permit free circulation.

In the accompanying drawings which 'the top of pipe B.

illustrate certain embodiments of the invention,-v

Figure l shows in vertical section, partly in elevation, an evaporator containing the elements of the invention;

Fig. 2 is a vertical section on an enlarged scale, partly broken away, of one of the vaporizing elements;

Fig. 3 is a side view of the cap illustrated in Fig. 2; y

Fig. 4 is a bottom plan view of said cap;

Fig. 5 is a top' plan view of the sleeve fixture at the bottom of said vaporizing elements;

Fig. 6 is a perspective view, enlarged, of one of the supports for the circulation tube; Fig. 7 is a vertical section, broken away, illustrating a modified construction of the lower part of said apparatus; and

Figs. 8, 8, 9 and 10 are diagrammatic views of other modifications hereinafter described.

Referring to the `form of the invention illustrated in Figs. 1 to 6: A represents a vessel to contain the liquid to be evaporated.` A is an inlet duct through which the liquid is introduced into the vessel, and A2 is an outlet duct through which the residue of the liquid after evaporation may be drawn oft'. These ducts may be provided with suitable means for closure (not shown). The vapors and gases of evaporation are conducted away through an opening A3 at the top of the vessel, and if desired, a vacuum apparatus may be provided to reduce the pressure within vessel A.

The elements of the evaporating device consist in a steam circulating loop which comprises steam pipe B, and a steam pipe B', the latter surrounding the former, and the delivery end of the pipe B opening near Considered separately the pipe B is a dead end pipe, the top being closed by a plug b. The pipe B is set into the header plate A4 at the lower part of the vessel, and extends through plate A4 so as to communicate with the steam supply passage C. The lower end of steam tube B is set into a sleeve or thimble D, made of soft metal, and having a hexagonal head to receive a wrench and a tapered, screw-threaded portion, which screws into a tapered, threaded hole in plate A5. When screwed into the hole by means of a socket vopen at top and bottoni.

wrench placed over the lube. the soft metal sleeve li compresses about the tube il and forms a tight joint. Between plat-es it and )Q is a drip cl'izjenibcr lil. to receive the condcnsed steam from tube l, and provided with a drip opening c. The plate if coustitutes the bottom of the liquid y sel, and is filetachubly secured to the walls of Vessel il; and the lower memlier comprising the plate fr* and the steam supply passage C is detarhably secured "on `the bottom of plaie il Surrounding and but slightly spaced from the pipe li. which constitutes the hea-ting element, is a cylindrical wall or tube l?. rlhe space between the pipe lli and the tube F has but little depth horizontally measured7 so that the liquid in the yessel which iiows into this space in the forni of a thin layer and therefore susceptible to yery rapid and ell'ectiye heating. rlhe tube F is supported at its lower end by radially disposed lins or brackets d, which are set into slots in the sleeye l). Each bracket (il has a shoulder d', by which theA lower end of tube F is sup ported and spaced from the sleeye D, and a spacing finger Z2 by which the tube li is spaced from the 'tube ld.

On the top of tube B is a cap G provided with a number of downwardly extending, radially disposed spacing fuis g. which project between tubes l? and'B, thereby holding them properly spaced apart at their upper ends. The cap G covers onlyT the top of tube B so as to leaye the top of tube lf open for the free circulation of the liquor and the outlet of the vapor.. 4 The margin of the cap Gf on its under side made to flare upwardly, as shown at y. so as to deiioctthe stream of boiling liquid baul; into the return spaces between the tubes F. rlhe level of the liquid to be eyaporated is shown at L.

iitcani is admitted to passage C', and thence to the steam pipes B, and baci: upon itself through the heating pipe B. rlhe thin layer of liquid between pipe B and tube F is heated rapidly to its ebullition point. and therefore becomes specifically lighter than the body of the liquor outside of walls F. rThis diderence in specific gravity together with the ebullition in the space between T3 and B causes the boiling liquor to be ejected freely and forcibly from the open top of tube lf, fresh liquor ente-ring at the bottom. The vapor passes off through outlet Eig. while the boiling' or foaming liquor is deflected by the cap G and turned back into the liquid space of vessel rlhe ste-ain which enters through pipe B to the top of the heater tube or pipe B circulates downward through pipe i3, and is coinlensed on 1@ipe lll and drains down on to plate Af', whence the water drains off through the drip port f1. The plate A slopes downward, as shown. from the steam inlet end to drip outlet end, thereby accomplishingl the double purpose of insuring rapid drainage of the water of condensation, and providing a steam inlet passage C of greater capacity near its intake end than atits other end. thus insuring a more even distribution of steam to the several steam pipes B rising from said passage C.

The arrangement shown in the drawings in which the entering steam from pipe B first comes in contact with the upper part of the heater tube B, is of distinct advantage, since as the steam delivers its heat and falls in temperature, it is proceeding toward the lower and cooler portion of the surrounding layer or iilm of liquid. Thus the transfer of heat per square inch of heating surface is rendered approximately uniform throughout the whole length of the heating surface. The influx of steam to the passage C may be so regulated that nothing except condensed water emerges at the port e thereby insuring the utilization of the entire latent heat, and also producing a pronounced drop in pressure between the supply header C and the induct steam pipes B. The maintenance of such a pressure drop guards against the chance of any one or more of the induct pipes being rendered inactiye by any slight local elfectr opposing the circulation. rlctiye' steam circulation in the deyice also tends to wash out any air that might tend to become poclreted in the heated tubes.

lt is also possible with this apparatus to maintain a low liquid level, resulting in a low hydraulic head and a consequent low average boiling point. IThe whole mass of liquor may be kept in such active circulation that the temperature is nearly uniform. Delicate liquors can therefore be evaporated safely, because of the small temperature difference found on this account, and on account Of the small temperature difference necessary to malte the circulation eectiyc. The actiyity of the circulation requires the liquor to be in Contact with the heat-ing tubes the minimuml time, and keeps the tubes well scoured from sediment.

Thus both the heating fluid and the heated uid are made to circulate continuously, and in the preferred form ofL apparatus the streams of heating and heatediiuid flow in mutually opposite directions, insuring a uniformity in the rate with which kheat is transferred from one fluid to the other.

rlhe above described apparatus'also posf scsses many structural advantages. The steam chest or header at the bottom of the l. containing' the steam passage C, is Y in one piece,A and is readily` separable from the vessel. The plate A5 is made in another' piece separable from the vessel. The top or cover of the vessel may also `be made removable or may be provided with a manhole. rI`hus any one or more of the tubes F or B, which are the most likely to be affected by corrosion, may be readily removed and replaced through the top of the apparatus; or if desired all the tubes, as well as the steam pipes B, may be removed together from the bottom by detaching and removing the plates A4 and A5 to which they are fixed. As the heating tubes B are secured only at the bottom ends and are free at their top ends, they may easily be cleaned by removing the circulating tubes F, and using an annular scraping tool, without removing the tubes B from the header.

In Fig. 7 certain structural modifications are illustrated by which it is possible to remove any of the tubes individually through the bottom of the vessel, which is desirable when the vessel is situated in a raised position where it is difficult or impossible to gain access to the interior of the vessel through the top. The steam pipes B are secured in a header plate A6 forming the top of the steam inlet passage C. The plate A may be removed through the bottom of the steam chest containing passage C. carrying with it all the pipes B as a unit. The header' plate A7 is similar to plate A5 excepting that threaded holes are tapered in the opposite direction; and the sleeves or bushings D are tapered in the opposite direction from sleeve D and are screwed into the plate A7 Jfrom the bottom. Thus the sleeves D may be removed individually from below, each carrying with it the tubes B and F which it supports. Said tubes may also be removed all together as a unit by removing plate A7, as in the form first described.

Referring new to the modification illustrated diagrammatically in Fig. 8, the steam enters through the header l, thence passes through the steam heating pipes 2, and the outlet and drainage is through header 3. The heating pipes 2 are surrounded by circulation tubes el, open at top and bottom, which confine a thin layer of liquid about and in contact with the heating pipes 2.

The circulation tubes i should be made in lengthwise divided sections, to provide for their easy removal, in some such manner as shown in 8a, in which the margins oit one tube section are sprung over the other. The operation will be clearly understood from the description of the form first explained.

In the modification illustrated in Figs. 9 and 10, the steam inlet pipes 5, are arranged in rows, each row rising 'from a header G, through which steam is supplied. There may be several such rows in the vessel, as shown in Fig. l0, which is a view at right angles to Fig. 9. Surrounding pipes 5 are educt steam heating pipes 7 which rise from headers 8,*surrounding headers 6. Circulation tubesV 9, open at top and bottom surround the steam heating pipes 7, and the circulation of steam and of the liquid takes place in the same manner as explained in connection with the first form of the invention. The inclination of the evaporating elements, as shown in Fig. 10, makes it possible to reduce the hydraulic head under which the evaporators work, since by reason of the inclined angle of the circulation and heating tubes the total vertical distance from the bottom to the top of each evaporating unit is diminished.

The invention is susceptible of embodiment in many other forms, the essential characteristic being that a heating element be situated in the liquid space of the vessel, and that a thin layer or body of the liquid be confined in contact with the heating element by a wall only slightly spaced from the heating element, which space is open at top and bottom to permit free circulation of the liquid upward through said confined space in Contact with the heating element. It is also desirable that the heating element should consist of a steam circulation duct, and that the circulation of the steam should be in the opposite direction to the circulation of the liquid being evaporated.

I claim:

l. In an evaporator, the combination of a vessel for containing liquid, a pair of concentric tubes the ends ot which project upwardly out of the liquid, means to circulate liquid upwardly through the space be tween the tubes and to heat the liquid as it circulates upwardly, and a member having an annular portion arranged to deflect the fluid issuing from said space outwardly into the space above the liquid.

2. In an evaporator, the combination of a vessel Jfor containing liquid, a pair of concentric tubes the ends of which project upwardly out of the liquid, means to circulate liquid upwardly through the space between the tubes and to heat the liquid as it circulates upwardly, and a member having an annular portion arranged to deflect the fluid issuing trom said space outwardly into the space above the liquid, and also radially to space the tubes with respect to each other.

3. In an evaporator, the combination of a pair of concentric tubes, means to circulate fluid along the space between the tubes, and a member fitting over the end of the inner tube, the member having an outwardly flaring surface outwardly to deflect the fluid issuing from said space.

4. In an evaporator, the combination of a pair of concentric tubes, means to circulate fluid along the space between the tubes,

Signed by me ai; W'en, New zunpshre, this 9th day of January, 1915.

VLLIM G. ABBOTT, Jn. wfjfn;esses ROBERT CUSHMAN, CHARLES D. WTOODBERRY.

and :L member ttng over the end of valle inner tube, the membel 4inn/'inegizm outwardly Haring Surface outwardly to deect the Huid issuing from said space, and having spacing nges extending inwardly between the tubes adaly to position the tubes with 1e speci; to each other.

Copies of this paient may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C.

Images