US2320343A - Vapor generator - Google Patents

Description

June 1, 1943;

Filed May 13, 1939 5 Sheets-Sheet 1 n6 i j! 3 3 v l i I22 IO\ 46 3? v v 34 I34 35 '32 :121

BY Era m G'fijzzley ATTORNEY.

June 1, 1943. E. G. BAILEY VAPOR GENERATOR Filed Kay 13, 1939 5 Sheets-Sheet 2 llll] llllilllllllll-IHII E. G. BAILEY June 1, 1943.

vAPon GENERATOR Filed May 13, 1939 5 Sheets-Sheet 3 (I) I C D INVENTOR.

Erwin GBaile BY ATTORNEY.

June 1, 1943. E. e. BAILEY 2,320,343

' VAPOR GENERATOR Filed May 13, 19:59 v5 Sheets-Sheet 4 I HM, MM. Mmltl' I low nfit er Level I i l P131 1 1- INVENT OR.

Jun 1, 1943.

E. G. BAILEY VAPOR GENERATOR Filed May 13, 1939 5 Sheets-Sheet 5 H 19h Mderlevel HEBQ Q QW Lazy Waterlevel m Drum;

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lilll BY Egin GBai/e buzz.

INVENTOR.

y W. W ATTORNEY.

Patented June 1, i943 UNITED STATES PATENT OFFICE VAPOR GENERATOR Ervin G. Bailey, Easton, Pa., assignor to The Bahcock & Wilcox Company, Newark, N. 1., a corporation of New Jersey Application May 13, 1939, Serial No. 273,398 Claims. (0]. 183-85) This invention relates to improvements in vapor generators and the invention may be considered as exemplified in water tube steam boiler improvements whereby the safe steaming capacities and the water storage capacities of such boilers, for a given drum capacity, are increased.

Among the objects of the invention are the eilective separation of steam and water with a minimum of steam and water separation space; ,the elimination of priming and decrease of water content in the steam leaving the steam and water drum to a minimum; the decrease of the amount of steam in the water in the steam and water drum to a minimum so that maximum density of water is procured; the increase of the safe steaming capacities of natural circulation steam boilers by minimizing the amount of steam in the downtake elements; the increase in boiler circulation rates; and improvements which will enable a given water tube steam boiler to operate. at maximum capacities under conditions of higher and more widely varying water levels.

To accomplish these objects the invention involves the combination of novel steam and water separators in a single steam and water drum and in certain definite relationships to the steam and water spaces of the drum, and the circulators discharging steam and water into the drum. It is to be understood, however, that the invention is not limited to all of the details of this combination.

With reference to the separators, it is an object of the invention to provide for the optimum of steam and water separation with a minimum of flow resistance and minimum of re-entrainment of steam in the water, and water in the steam after the initial separation.

The invention will be described with reference to the embodiments illustrated, in the accompanying drawings, and other objects of the invention will appear as the description proceeds.

In the drawings:

Fig. 1 is a vertical section of a steam generating installation which includes an embodiment of the invention,

Fig. 2 is a transverse vertical section of a steam and water drum with the illustrative separator therein;

Fig. 3 is a plan section of a steam and water drum showing the arrangement of a number of the illustrative separators;

Fig. 4 is a vertical longitudinalscction of the, Fig. 3 drum;

Fig. 5 is a vertical section on the line- 5--5 of Fig. 6, illustrating an embodiment in which the separator casing i rifled;

Fig. 6 is a horizontal section on the line 6-6 oi'.Fig. 5;

' Fig. 7 is a vertical section (on the line 1- of Fig.8). of an embodiment in which the separator casing is formed with parallel lands or within the drum by the side grooves within the steam and water inlet and is partially rifled throughout the remainder of the separator casing;

Fig. 8 is a horizontal section on the line ll of Fig. 7;

Fig. 9 is a vertical section (taken on the line 9-4 of Fig. 10) of a separator embodiment in which a single groove extends from the steam and water inlet to the outlet for separated wa ter; and

Fig. 10 is a horizontal section on the line Ill-i0 of Fig. 9.

The invention is well adapted to attain a high degree of steam and water separation in high pressure and high capacity steam generators such as that indicated in Fig. 1 0! the drawings.

In this installation it is to be noted that the steam and water separation is accomplished within a single steam and water drum, thus illustrating the ability of the invention to provide effective steam and water separation with a minimum of steam and water drum volume or capacity.

In the Fig. 1 installation the steam and water mixtures are discharged by the circulators II- at high velocity into the drum l2. These circulators are shown as having their inlet ends connected to a header i4 which-receives the and water from a plurality of risers. Some or these risers define the walls and other boundaries of the furnace l6 and are subject to the high temperatures thereof. Other risers, such as Iii-40, define the walls of gas'passes 22 and 2A and are subject to'high gas temperatures at those positions.

Steam and water is separated within the drum It, the steam proceeding through the tubes I}! to the superheater I 34 while the separated water proceeds through the downcomers 30 to lower headers 32-45, the latter being otherwise appropriately connected into the boiler circulation as indicated. The steam and water discharged into the drum I2 through the circ'ulators ll enters a separator inlet chamber "which is formed plate M, the upper and lower plates 44 and 46, and complementary end plates indicated at 48 and 50 in Figs. 3 and 4 of the drawings. This inlet chamber extends throughout the major portion of the length of the drum and has connected thereto a plurality of rifled, steam and water separators ii, the air rangement of these separators being indicated in Figs. 3 and 4 of the drawings and their specific construction being indicated in Fig. '2 and Figs.

. 5-9, inclusive, of the drawings.

In 'the illustrative separators a plurality of forces are eifective during the operation of the vapor generator. Vapor and liquid mixtures enter the whirl chambers from the inlet chamber Ml with a considerable velocity head. Their flow is Substantially tangential. to the whirl chambers and it may also be considered as substantially horizontal. These circumstances result in a swirling film of liquid flowing along the wall of the whirl chamber and the centrifugal for.e thus produced is effective in separating the vapor and liquid.

As the mixture of liquid and vapor enters the whirl chamber horizontally at a high velocity the tendency is for it to continue its motion in the same horizontal zone, so that the film of liquid tends to flow back upon itself creating a layer of liquid of greater depth. While this tendency is naturally modified by the force of gravity, which imposes a vertically downward component, on the horizontal velocity component of the incom-i ing stream, ;.thus resulting in a'generally downward direction of the fllm of liquid on the whirl chamber wall in the form of a spiral, the centrifugal force being greater than gravity is such thatin acting upon the layer of liquid, the liquid displaced in the thinning down of the layer fiows both upwardly and downwardly of the wall of the: whirl chamber from the horizontal zone into .which the incoming stream is projected. It is desirable, ,however, toavoid these conditions. As for example, .the liquid displaced upwardly of the whirl chamber wall may impactiwith the top of the whirl chamber resulting inthe splashing .of such liquid into the steam space in the center of the chamber, where it might be picked up by steam and carried'tothe multiple plate sepailator. or, if the distance above the horizontal z'one,"to which reference has been made, to the top of the chamber'is adequate to prevent this happening, when the centrifugal force in this liquid is dissipated the action of gravity will be to gene the liquid to flow down-the whirl chamber trial and on contact with the high velocity incoming stream will tend to splash with the same pbs'sibility of resultantjpickup by the steam, which is; of course, undesirable. In order that the forces involved might be utilized most efliciently, and the best results as to steam-free watg'r andwater-free steam be obtained, it is necgsary that these conditions be avoided, and the m of liquid removed from the incoming zone, and... all of it discharged downwardly from the bottom of the whirl'chamber just as quickly as ble. The rifled or spirally grooved interior 'all of the whirl chamber provided by this invention performs this function, as it utilizes the entirely of the incoming stream to augment the eneet of the force or gravity, and not only defifi teiy initiate but maintain the downwardly flow 6f the liquid'filmtowai-d the restrictedoutlets atthe lower end of the whirl chamber. Such restrictd outletsjare 'shownas limited to narrow annular zones defined externally by the rifled wall oftlie' whirl chamber and the base, or pan, 88;"; They maybe separated by short helical vanes such as thoseindicated at 58 and ill in Fig. "The latter arepreferably co-ordinated with tlie rifllng, and when secured to the whirl chant br they serve as supports for the pan, or base, 58". The forces involved in the flow of separated whterdownwardly through these outlets prevents the"establishment of liquid levels in the whirl chamber corresponding to the drum liquid levels and enables the vapor generating installation to effectively operate at drum liquid levels ranging essentially from the top to the bottom of the cylindrical whirl chamber. "Such as is indicated by the lines'AB and CD of Fig. 5. v

Beneath the multiple plate separator I2 for each whirl chamber the steam outletmember 62, formed in the shape of a hollow frustum of a cone, is secured at its upper circumferential edge to the top of the whirl chamber by brazing or welding as indicated at 64; This member not 'only prevents the liquid swirling in an annular layer at the upper portion of the whirl chamber from being whipped upward so as to be caught by the plates of the separator 52 but also causes liquid falling from the separator 52 to be deflected toward the center of each whirl chamber.

The modification of the separator indicated in Figs. 7 and 8 of the drawings is similar to that above described in many respects, the main difference residing in the extent of the rifllng. In the Fig. 7 modification the whirl chamber is not. completely rifled, the rifllng being limited to asubstantiaily helical band beginning in the inlet. structure Ill and continuing through the outlet for the separated water. This leaves a plain sur-f faceportion of the interior surface of the whirl chamber between successive groups of the rifiing elements. Such a plain surface portion is indi-. cated at I2, disposed between the elements oi the. rifling H and I6 of an upper group and elements 18 and 80 of a lower group. J

The embodiment indicated in Fig. '1 of the drawings has a whirl chamber with rifllng so,

arranged that at the time the liquid in the grooves. makes one circuit of the whirl chamber, it is below theentrance port, and there is therefore no building up of a return liquid upon the enter-; ing stream. The rifiing is thus of benefit in eifecting more definite downward fiow of the liquid swirling along the wall. I

In the embodiment indicated in Figs. 9 and 1-0 of the drawings the interior of the casing 8! is formed with a single helical groove beginning at the position indicated at 82 which is disposed approximately at the junction of the inlet struc-'- ture 84 and the casing 8L. From that point the; groove 86 extends helically to and through the water outlet which is formed by the base 90 and the surface of the casing 8! adjacent the base. i

As indicated in Fig. 2 of the drawings the whirl chamber casings are secured to the plate 42 by sleeves H0 fixed to the plate and provided. with flanges H2 adapted to fit against compiementary flanges ill secured to the inlet strue-E tures 8 which are rigid with the casings II."

The whirl chamber casings ii are further fixed in position by supports lid-I22, the latter of which may be welded to the drum with the mem her I 2!! detachably secured thereto.

' Operating pressure, pounds Ratio This ratio is a measure of the gravity force. which separates the steam and water. Steam will be entrapped in the body of water beneath iating water are discharged into the body of water in the drumbelow'the .water level or if the steam and the circulating water impingexdownwardly on the water surface. It is evident that theseparating force of gravity alone decreases greatly with increased operating pressures so that it becomes increasingly difilcult to remove any steam entrappedin the body of water as the operating pressure increases. .Any steam so en-' trapped is carried with the circulating water into 9 the. downcomersand, due to the smaller specific weight of the steam, the circulating head is re-' duced and hence the circulating system balances out at a lower circulating flow. The present in- -"vention causes all of the steam and circulating water to be received within separate whirl chambers within the boiler drum, and, by utilizing centrifugal force which is several hundred per centgreater than the force of gravity, the steam and water are completely separated. The steam is discharged vertically upward from the whirl vchambers at low velocity and away from and above the surface of the water. The separated water is discharged downwardly from the whirl chambers into the body of water within the drum.

and below theupper surface of. that body of water. In this way the body of water below the surface is practically free from steam, and the steam space above the water surface is practically free from moisture regardless of operating pressure or capacity. Therefore, the water in the downcomer supply being practically free from steam insures that the maximum circulating head is produced and the optimum circulating flow is attained, and at the same time the steam being practically free from moisture insures the supply of clean steam to the superheater and subsequent turbine, and the elimination of the troubles previously encountered in such appa- -ratus due to moisture and solids carryover in the I factor resulting from such increased water shortage. These characteristics of the invention also permit noteworthy decreases in the costs of original installations byinsuring satisfactory circulating characteristics and good quality steam production with minimum of drum capacity.

While the invention has been described with reference to certain particular embodiments thereof it is not limited to all of their details. On the contrary, it is to be considered as of a scope commensurate with the scope of the subjolned claims.

What is claimed is;

1. 'In a separator for fluids of diflerent densities, means constituting a whirl chamber, an 'inlet means so disposed as to promote the whirling movement of fluids within the chamber, the

inlet means having its longitudinal axis ofl'set with respect to the longitudinal axis of the whirl chamber and transversely related thereto, the

whirl chamber being rifled internally with the with a lead which is at least as great a the A which is .at least approximately equal to the width'of the inlet: axially of the whirl chamber.

2. In a fluid separator, a whirl chamber casing of circular cross-section defining a separating zone, means forming a tangential inlet to said zone, means wherebya fluid stream is discharged through the inlet-at high velocity, and difierent outlets for separated, fluids of different densities, the casing beingrifledfrom the inlet toward the outlet for the separated fluid 0! higher density, the rifling being such that the lead of any element thereof is at least as great as the width of the inlet axially-oi the whirlchamber.

3. In a fluid fseparator, a whirl chamber of circular cross section, means forming a tangential inlet to said chamber, spaced outlets for separated fluids of diflerentdensities, means in the zone ofthe perimeter of the chamber for promoting movement of thefluid at higher density toward the outlet fo'r that fluid, said means consisting of a helical groove extending from the elevation of the inlet to a position below the inlet width of the inlet axially oi the whirl chamber.

4. In apparatus for separating fluids of diflerent densities, a whirl chamber of circular crosssection, means forming an inlet tangentially arranged relative to'said chamber so that a stream of fluids entering the chamber at high velocity will tend to set up a'high velocity circular movement of fluid withintthe chamber, spaced outlets for separated fluids of diflferent densities, and means limited to the peripheralzone of the chamber and disposed adjacent the inlet for initiatin movement oi the incominsffluid stream toward the outletfor the separated fluid at higherdensity, said means consisting of a group of spaced helical grooves inthe circumferential wall of said whirl chamber "extending from the elevation of the inlet to a position'below the inletandbeing such that the lead ofany groove is at least as great as the width of the inlet axially of the whirl chamber.-

5. In a fluid separator including a shell providing a whirl chamber of circular cross-section and extending belowa'liquid level, inlet means, whereby the whirl chamber tangentially receives unseparated mixtures of gas and liquid at high velocities, means forming, a gas outlet at one end of the whirl. chamber, aliquid outlet disposed toward the opposite ends of the whirl chamber and limited to a zone adjacent the perimeter of the chamber, and helical ribs projecting into the whirl chamber from the shell and extending from a position adjacent the inlet to initiate a helical motion of theliquidtoward its outlet and to prevent the second whirl of the liquid from the inlet from remixing impact upon the first whirl, the

j pitch of the said ribsbeing at least as great as

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