US1501646A - Evaporator coil - Google Patents

Description

July 15, 1924. 7 1,501,646

s. BROWN EVAPORATOR COIL Filed Feb. 1, 1922 o o o o o o o l; ll 5 I 4 I N VEN TOR.

A TTORNEVS provided in the upper Patented duly 15, 1924.

urrso STATES P AT E STANLEY BROWN, 0F GARDEN CITY, NEW 'YGBK, ASSIGNOB T0? THE GRISCQM-RUSSELL COMPANY, OF NEW YORK, N. Y., A GORPOBATIGN 0F DELAWARE.

EVAPORATOR COIL.

Application filed February To aZZ whom it may concern.

Be it known that I, STANLEY BROWN, a citizen of the United States, residing at Garden City, in the county of Nassau, State of New York, have invented certain new and useful improvements in Evaporator Coils; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to evaporator construction, and has to do particularly with the construction of a heating element for evaporators employed in the distillation of salt water or other water having scale-forming properties which render it unfit for use in steam generating boilers.

Evaporators of this general type extensively used at the present time commonly consist of a chamber for the liquid to be evaporated with transverse upper and lower manifolds for the heating steam, and banks of heatin coils extending between the manifolds an furnishing the necessary heat transferring surface required for vaporizing the liquid. In the operation of the apparatus impure water is admitted to the container and steam is supplied to the heating coils. It has been found that the heating coils must be closely wound and that the various coils must be arranged to occupy the spacewithin the container as completely as possible in order that a satisfactory output for the apparatus may be obtained. The close positionin of the coils and the proximity of the a jacent convolutions of each coil increase the tendency of scale deposits to form a bridge between convolutions and, as a result, the coils must be cleaned at frequent intervals.

Evaporators of this type are now commonly operated with the heating coils completely submerged, a battle element being ortion of the container for diminishing t e agitation of the liquid surface resulting from violent boiling and preventing articles of the liquid be coming entrained in the evolved vapor as it passes out of the apparatus. In this arrangement the entire surface of the heating coils is available as effective heat transferrin surface for vaporizing the liquid, but

it as been found that the coils must be heating element in which any sca illustrating in section modi 1,' 1922. Serial no. ceases.

wound so closely that scale will nevertheless accumulate over the surface of the coil tubing and that scale formations bridging adjacent turns of the coils are likely to form after the apparatus has been in use for a short time. I

It is a principal object of the present invention to class a heatmg element which will accumu late a minimum of scale or impurities when used for evaporating water having scale forming properties, and in which the tendency for bridging over of the scale between adjacent coil turns may be avoided without It is also an object to provide a heating coil which presents an increased heat transferring surface fora given length of coil without increasing the sectional area of the fluid passage.

It is a still further object to provide an evaporator of the above type comprising a e or de posit accumulated upon the heat transferring surfaces may be thoroughly removed in a quick and convenient manner.

I have illustrated a preferred embodiment of my invention in the accompanying drawings; in which Figure 1 is a vertical sectional view of an evaporator embodying my provide in an apparatus of this invention; Fig. 2 is an elevational view showing a heating coilfor an evaporator having a fluid passage of circular cross section; Figs. 3 and 4 are, respectively, views similar to Fig. 2 illustrating eating coils according to my invention; Fig.

ed forms of fluid passage; and Fig. 6 shows a modified type of coil embodying my invention.

Referring to Fig. 1 of t e drawings, 1 indicates the shell of the evaporator effect which serves as a container for the liquid to be evaporated. The heating element consists essentially of upper and lower manifolds 2 extending transversely of the a paratus and interconnected by means of the eating coils 5 is a view outer end may be provided with a roller su port 6 so that the heating element may e conveniently rolled out of the evaporator she'll onto the. floor in front of the appara tus, and may thus be conveniently inspected or repaired. Steam is admitted to the upper manifold through the inlet 7 from whence it traverses the various coils of the heating element. The condensate accumulates iii-the lower manifold 2 and is discharged through the outlet 8. Continuous operation. of the,

evaporator is efiected by supplying steam to the heating element in 'sufhcient quantity to maintain the contained liquid in a state of constant ebullition, a bafie 9 being prefer ably provided to surround the upper ends of the coils and. minimize the agitation at the upper surface of the liquid.

in Fi 2 l have illustrated a heating coil in whio the fluid passage is of circular section throughout. The coil is wound in helical fashion, the successive turns of the coil being equally spaced, and it is understood that suitab e end connections are provided for fastening the coil to the upper and lower manifolds with a fluid ti ,ht connec tion. It is evident that the e eotive heat transferring surface in any coil is dependent upon the number of turns which it comheat transfer eihciency,

prises. It is consequently common practice to w nd the turns of the coil as closely adjacent as is compatlble with the scale forming qualities of the liquid to be eva orated.

Aocurnulations of scale will eventual y form on the coil and bridge over between adja" cent turns with a consequent decrease in and the coils are accordingly wound wit a pitch such that a bridging over of the scale will occur at in tervals sufliciently remote to avoid excessive cleaningof the coils by manual means.

I have illustrated in Fig. 3 a heating coil embodying my invention. The coil is wound in helical-form with a number of turns equal to that of the coil shown in Fig. 2. As shown at 11, however, the section of the coil tubing is distorted from s circular form and is here shown-as an oval figure with its maximum dimension lying in a horizontal direction. The smallest cross sectional dimension or the tubing lies in a direction substantiall arallel with the length of the coil, an t is coil tubing when viewed from the side as shown appears to be appreciably thinner than a tubing of circular cross seci e-e tion of thesame area. The vertical distance between edpacent faces of successive coil turns is thus. appreciably increased, the

amount of this increase being equal to the difierencebetween the diameter of a circular section and the minimum. dimension of an oval section of the same area, the-oval section bein. formed from the same tubin Since the bridging over of scale between a jacent coil turns depends directly upon the proximity of. the adjacent faces of such turns, it is evident that with my improved coil the tendency toward such bridging over of the scale is efiectively diminished. The distanceindicated at B in' Fig. 3 repre sents the distance over which scale must accumulate before a bridging between turns is efiected. It is to-be noted that this distance B is materially greater than the corresponding distence A indicated in Fig. 2

.for a coil of similar construction :but having a circular section.

n Fig. 4 I have illustrated a coil embodying my invention in which, by way of exam- .ple, the distance A between adjacent feces of successive coil turns is shown equal to the similar distance A in Fig. 2. In myimproved construction it is possible to main tain the distance A the same as that employed in a coil of circular section, and. consequently provide a coil of the same scale resistin quality and of. the same length, but having a greater number of turns. Such a coil comprises a fluid passage whose offer tive length is increased with e corresponding increase in available heat transferring surface without increasing the dimensions of' the heating coil. The ends of the coil which are adapted for adjustment to the manifolds of theevaporator may conveniently'be made of circular section, if desired, so that coils embodying my invention may readily be installed in existing apparatus.

In my improved form of coil construction the coil section is distorted from a circular form and consequently a tubin of this type will present :a greater perip .ery than a circular tubing of the same sectional area. Hencein a fluid passage of a'given capacity the eifcctive heat transferring surface along a given length of tubing is increased proportionally to the increased periphery of the section. shown in Fig. 3, which comprises the same number of turns and consequently substantially the some length of tubin as occurs in a coil having a fluid passage 0t circular section, the effective heat transferring surface of the coil is increased due to the distorted section and at the same time the scale resisting qualities of the coil are bettered. In the coil shown in 4.- the scale resisting qualities are substantially the same as that of a coil of circular section, but the heat transferring properties oi. the coil are in- In the coil shown in Fig. 6 are arranged one abo ed on evaporator heating coils of this type by subjecting the coilsto an-abrupt change in temperature. This. may vbe conveniently accomplished byv successively passing cold water and high pressure steam through the coils. When the superheated steam. enters the cold coils the metal of the tubing will suddenly expand and crack the scale deposit on its outer surface, after which the scale will drop oil or hang loosely on the coils in condition to be readily removed. With my improved coil construction the stresses due to sudden expansion of the coil tubing in this fashion tend to render the section of the tubing circular. Hence some portions about the periphery of the tubing will expand to a greater degree than others,

and this inequality in expansion willmaterially facilitate cracking ed or the deposited scale.

in the foregoing description I have referred to an evaporator emplo ing coils of the helical type, but it is evi ent that my invention may be embodied in coils of any type designed for use in evaporators or similar apparatus. For instance, in Fi 6 I have illustrated a coil of the kind emp oyed in evaporators known to the trade as the Weir type. in this type of evaporator,

" which is particularly well known in England, a plurality of flat coils of thetype vs the other within the evaporator shell and serve to contain the steam which is supplied as heating medium to theevaporator. Each coil 15 consists of several convolutions in a horizontal plane and is provided with end connections 16 for attachment to the inlet and outlet manifolds. 7

In a coil of this type embodyin my invention the coil tubing is distort circular form and is wound in such manner that the broad faces of successive convolutions lie adjacent each other. It is thus evident that the distance between the adjacent faces of successive convolutions is materially greater than the corresponding distance in a similar coil composed of a like length of tubing of circular cross section.

The increased distance between adjacent coil turns makes bridgi over of scale from turn to turn more di cult, and the intervals at which the coils must be manually cleaned are correspondinglyless frequent. 0n the other hand, the distance between adjacent convolutions may be made the same as in a coil composed of tubing of circular cross section by employing a greater'length of tubing when formin the coil. As a result, a greater amount 0 ac- 'a square or diamond shaped figure having from'a tive heat transferring surfacewill be pre sented in each coil without impairing its scale resisting properties. Furthermore, in a coil of the Weir type embodying my invention, it is, to be noted that the broad faces of adjacent convolutions of tubing extend in a substantially vertical direction,-

and thus are more readily freed from scale 7 when it is cracked ed by subjecting the tub-'.

ing "to an abrupt change in temperature. That is, the exfoliated scale will be'largely removed during the cracking; process by merely falling to the bottom of the evaporator shell.

Vfhilell have described my improved coil construction as comprising a tubing of oval section, it is obvious that any section distorted from a circular form may be era-f ployed; For instance, the flattening out of the tubing may be carried further as indicated at 12 in Fig. '5, so that the cross sec tion presents upper- -and lower surfacm which are substantially fiat and parallel, the side surfaces being rounded. liilrewise,

90. rounded corners such as indicated at 13, or

a shape such as shown at. 14:, may conveniently be employed. Uther coil shapes will suggest themselves to those skillediin the. art and various other changes mayhe made in the specific embodiment of the invention within the full scope of the appended claims.

I claim': I

1. lln an evaporator, the combination with a containing shell of a heating elemerit within said shell, comprising a continuous tubing having a plurality of convolutions, the cross section of said tubin being distorted from acircular form, an the broad faces of successive convolutions being adjacent, whereby a maximum clearance between convolutions .is obtained and". bridging over of scale between sumssive convolutions is restricted. no

2. In an evaporator the combination with a" containing shell oii a heating. coil comprising a continuous tubing having a plurality of convolutions arranged one above the other, the tubing of said coil having its 1-15 greatest cross sectional dimension eatend- 7 ing in a substantially horizontal direction w ereby a maximum clwrance between adjacent convolutions is obtained and bridg its ing over of scale is correspondingly 'retransferring surface Without diminishing the distance between adjacent feces of successive convoiutions.

4.111 an evaporator the oembination with a containing shell of a scale resisting heating element comprising a continuous tubing Wound into convoiute form with adjacent ccnvolutions substantially equi-distent throughout the extent of the heating element, the tubing forming said heating element being of cross-section flattened to such i eeitnee extent that the flattened faces Wiii flex a substantial emennt upon abrupt temperature change and having the said flattened faces of successive convolutions lying adja-- cent .Whei'ehy an ample clearance between convoiutiens is obtained to thereby restrict bridging ever of .seaie between adjacent c0nveiutiens.

In testimony whereof Iefiix my signature.

STANLEY BRQWN.

Images