US2300852A - Liquid vapor separating device - Google Patents

Description

NoY. 3, 1942. o, woo 2,300,852

LIQUID VAPOR SEPARATING DEVICES I i I Filed Oct. 31, 1939 2 Sheets-Sheet 1 Invento r: Orla .L,. Wood,

His A tof n' eg.

Nov. 3, 1942. 0. L. WOOD r 2,300,852

LIQUID VAPOR SEPARATING DEVICES Filed Oct. 31, 1959 2 Sheets-Sheet 2 Inventor:

Orla 1... Wood,

Hi5 Attorn eg.

Patented Nov. 3, 1942 UNlTE sures menu) VAPOR sEPAitA'riNo DEVICE Orla L. Wood, Schenectady, N. Y., assignor to General Electric Company, a. corporation of New York Application October 31, 1939, Serial No. 302,179

2 Claim. (Cl. 122491) The present invention relates to liquid vapor separating devices, such as are used in mercury boilers for removing liquid particles from the mercury vapor before such vapor is conducted to turbines or other consumers. Removal of liquid particles is important to avoid damage to turbine buckets and other parts, due to impinging of liquid particles at high velocity onto such parts. It should be noted that all solid matter, such as the various oxides and dirt or dust, light enough to be carried in the vapor stream, is not to be separated with the liquid particles or prevented a free exit from the drum as this is the only means of removing such matter and preventing its accumulation.

The object of my invention is to provide an improved construction and arrangement of liquid vapor separating drums, whereby such separation may be effectively carried out.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accom-..

panying drawings.

In the drawings Fig. 1 illustrates a perspective view of a mercury liquid vapor separating device or drum in accordance with my invention; Fig. 2 is a section on line 2-2 of Fig. 3; Fig. 3 is a sectional view of Fig. 1; and Fig. 4 shows a modification embodying my invention.

The arrangement comprises a cylindrical shell or drum ii) to which are secured a plurality of up-tubes H by means of welds 12. The tubes H project through openings in the side of the shell i0 over an area of approximately 90 angular degrees. The lowest row of tubes i3 projects further inward than the upper rows to bring it above the maximum liquid level in the drum in order to prevent reverse circulation of fluid during operation. The tubes may be arranged to line the wall of a combustion chamber. not shown, in which heat is radiated to the tubes. Mercury liquid is conducted to the lowerends (not shown) of the tubes l I by means of a downtube i5, which has an upper end secured to an The upper end of thedown- During "operation mercury liquid is continu ously fed through the down-tube M to a plurality of up-tubes' I l and heated in the latter.

The mixture of liquid and vapor thus formedin theup-tubes H is discharged from the latter .into the drumlllto beseparated therein. The

liquid is recirculated through the down-tube l4 a sleeve concentrically'spaced from the conduitiS and having one end fastened tothe shell byan annular weld 2 andanother end contacting the conduit is and sealedthereto by a weld 22. This arrangement of sealing the conduit l9to the drum it permits relative expansion between them without setting upexcessive stresses during operation, and also prevents'localized cooling of a section of the heavy wall drum which also wouldv result in excessive stresses since the conduit 19 is much cooler than the drum.

. The modification of Fig. 4 shows an arrangement in which a liquidsupply conduit 23 projecting-into a shell 24 is sealed thereto by means of a sleeve 25"concentrically spaced from the conduit 23 and having one end secured to the shell by a weld 26, and another end engaging the conduit 23 and fastened thereto by a Weld 21. In contrast to the arrangement of Fig. 1 the sleeve 25 of Fig. 4 is located external to the drum. .The other elements of Fig. 4 are identical with those of Figs. 1 to 3 and Will be described hereinafter in connection with them. The liquidsupply conduits ill have ends connected to and discharging into a supply trough.

28 running along the drum and located centrally above the normal liquid level in the drum. A plate or trough 29 with perforations Bil-and a right-hand upward-bent end portion 31 is located slightly below the supply'conduits i9 andserves to reduce stirring up of the liquidl'pool in the bottom of the drum by changing the direction and reducing the velocity of liquid entering the top of the plate 29 on the inside of bent portion 3|. The-upward-bent end portion Slis connected to the adjacent drum wall by a perforated strip 32. The perforations in the strip 32 and the plate 29 admit liquid to the bottom portion of the drum but prevent the admission of large pieces of solid matter. In a preferred embodiment the perforated plate 29 and the perforated strip 32 are covered by screens of wire mesh 32a, spot-welded to the plate 29 and the strip 32 respectively. These screens act as filters to prevent solid particles above a certain size from entering the down-tube [4. The screened plate or trough 29, 3| also acts as a chamber for mixing cold liquid received from the trough 28 and hot liquid received from up-tubes II. In this manner cold liquid discharged from the supply trough 28 is prevented from coming into direct contact with the hot walls of the drum [0. The plate 29 is supported by a plurality of posts 33 and 34. Each post has a base 35 secured to the shell by a weld 3S and acting as a support for the post proper, which is secured to the base by a weld 31. The purpose of these bases is to avoid changes of the drum material which is heattreated in the factory. The bases are attached to the drum prior to the heat treatment, whereas the posts proper are secured to the plates in the field, that is, subsequent to the heat treatment. The edges of the perforated strip 32 are fused to the trough 29 and the drum I9 respectively.

As a further means for preventing spattering of the liquid pool by the incoming vapor, I provide a plate 38 slightly above the supply conduits l9 and running along the entire drum. The plate 38 is secured to the drum through the intermediary of a base 39 in the form of a narrow strip welded to the shell prior to its heat treatlets of the up-tubes H and the inlet of the discharge conduit ll whereby the mixture of liquid and vapor on its flow along this path is separated into liquid and vapor. More specifically the arrangement comprises a baffle 49 with a major portion slightly inclined away from the vertical center line and a minor portion at a right angle to such major portion and slightly spaced from the right-hand edge of the trough 28. A narrow gap 49a is thus formed between the adjacent edges of the supply trough 28 and i the deflecting baffle 49. The function of this gap 40a is two-fold. During starting, the gap forms a passage to conduct liquid discharged towards the baffle 49 into the trough 23 and thus keeps the trough 28 filled or, from another viewpoint, prevents the high pressure then existing in the drum H) from forcing liquid from the trough 28 through the supply pipes l9. It is to be noted here that in the ordinary installations little or no liquid is supplied through the conduit l9 during the starting operation. The other purpose of the gap 48a is during normal operation to prevent excessive supply of hot liquid from the deflecting bafile 40 into the supply trough 28 because such excessive supply would interfere with the free supply of cold mercury through the conduit [9 and the uniform mixing of cold and hot liquid on top of the plate 29. The baffle 40 runs the length of the drum and faces the entrance side of the up-tubes H. The baffle 49 is supported by a plurality of webs 4i welded to the baffle 49 and the aforementioned elements 28 and 38. The right-hand side or face of the bafile 49 receives the impinging jets of vapor and liquid discharged from the tubes II to dissipate their kinetic enerky. A plurality of auxiliary baffles 42, 43, and 45 are secured to the inner surface of the drum If) for properly directing the jets from some of the tubes ll towards the main baffle 49. Each of the auxiliary bafiles 42 and 43 has a plurality of separate axially spaced portions or sections secured to a base 44, which latter is welded to the shell. In order to prevent the flow of fluid through the the spaces formed by the separate portions of the baffles, these spaces and the adjacent edges of these portions are covered on both sides by strips 46 and 41 loosely secured to 1 the baffle portions by means including pins 48 and Washers 49 (Fig. 1). During starting, the baflles 42 and 43, being relatively light, heat up much more rapidly than the adjacent wall portions of the shell. Excessive heat stresses are avoided by the separation of these baffles into several sections.

Substantially all of the entering liquid impinges onto the face of the baffle 49, which guides it downward into the trough 29. The upward bent portion 3| of the latter serves to catch all of the liquid directed towards it by the baffle 49. As pointed out above, the baffle 40 is located in the middle of the drum. The large space thus formed between the battle and the outlets of the up-tubes permits access of the interior of the drum for inspection without necessitating removal of any of the auxiliary bafflles. The long path of the liquid from the face of the baflle 40 down into and across the trough 29 and through the screened perforations in the latter permit vapor still entrapped in the liquid to free itself together with any dust or dirt present, and also to reduce the liquid velocity and thus to aid in releasingof the vapor before the liquid enters the down-tubes M. A restriction to flow of mercury by the screened, perforated plate 29 normally causes the formation of a boiling pool of mercury on top of the plate 29. Dust particles contained in the mercury are thereby readily re leased therefrom together with vapor and carried out through the discharge conduit I1. The removal of dust particles with the vapor is desirable in mercury boilers in View of the absence of any blow-down devices. The removal of dust particles with the vapor is facilitated by the provision of a free passage formed on the left-hand side of the drum, that is, from another viewpoint, by the absence of any obstacles in the path of the vapor from the left-hand portion of the plate 29 to the discharge conduit H. At high liquid level, the level may be somewhat above the perforations 30 in the trough 29, but the arrangement is such that normally the liquid level will not reach the level of the entrance to the lowest row of tubes l3.

As the mixture impinges on the main bafiie 40, the vapor rises toward the discharge conduit ll'. This vapor contains entrained liquid particles and to remove or separate these particles from the vapor, I provide two curved baflles 5G and 5!. The bafile 5| comprises a plurality of portions or sections 52, 53 and 54, the rear edge of each being secured to the aforementioned bafile 45 by a weld 55. In order to prevent direct discharge of fluid through the slots formed between the adjacent sections 52 and 53 of the baffle 51 and also through slots of corresponding sections of the bafiie 45, I provide sealing strips 56 to cover the slots formed between adjacent sections of the baflies and 55. Each sealing strip has a portion engaging adjacent sections 52 and 53 with an edge secured to the section 53 by a weld 51 (Fig. 2). This portion of the sealing strip 56 engages smoothly the lower surfaces of the sections 53 and 52 and envelops the edges of the sections of the baflle 55. In addition, each sealing strip 56 has a hairpin shaped portion with an edge secured to the section 52 by a weld 58. In this manner the various sections 52, 53, and 54 may expand freely relative to the drum. The sections 52, 53, and 54 are supported on the drum by posts 59 secured to bases or connecting members 60, which latter are welded to the drum. The connecting members 60 are provided prior and the posts 59 subsequent to heat treatment of the drum. As shown in Fig. 2, each post '59 has a reduced end portion 6| projecting freely through an opening 62 in the bafile section 53. A washer 63 is welded to the end of the reduced post por- 4 tion 6| securely to hold the section 53 on the post 59 and to permit slight movement of the section 53 relative to the post 59 during operation. The washer 63 is enclosed by a cap 64 welded to the section 53 and preventing the flow of fluid through the clearance between the post 59 and the opening 62.

The bafile 56 likewise includes a plurality of sections 65, 66, etc. welded to vertical partitions or ribs 67, which later are secured to the bafiie 5|. The sections 65 and 66 are sealed by strips 68 and 69 on opposite sides of the baflie, covering the slot formed between the sections and held in position by means of pins with washers H and 12 secured to opposite ends of the pins. Metal strips 13 and 14 are fused to the lower edge of the b-aflle 50 to form troughs on opposite sides thereof for receiving mercury liquid flowing along opposite surfaces of the baffle 50. The liquid thus collected in the trough is conducted to the trough 29 by means of a plurality of pipes A similar trough is formed by a strip 16 at the lower edge of the baflie 5| for receiving mercury liquid removed from the vapor as it impinges on lower side of the bafile 5|. The liquid thus collected is discharged through pipes 11 into the trough formed. by the strip 13 and the bafile 5|].

During operation, as pointed out before, a certain amount of liquid in the form of a spray is carried against gravity with the major portion of the vapor over the top of the main baffle 40. The curved bafiies and 5| guide and direct this flow downward on the rear side of the main baffle 40. The vapor flow turns around the outlet ends of the bafiles 50 and 5| towards the discharge conduit H. The curvature of the shell, which is about the same as that of the left-hand portion of the bafile 5| guides the vapor flow above the bafile 5| to the vapor outlet H.

The larger portion of the spray coming over the top of the baflie 40 is guided by the baifie 50, either by the inside or the outside surface thereof. The liquid is collected in thetrough at the lower end of the b-afiie 50 and drained through the pipes 15. The inside surface of the baffle 5| picks up some of the remaining moisture carried by the vapor fluid and collects such moisture in the trough formed by the strip 16 on the outlet end of the baflie 5|. Also as the vapor discharges into the large opening in back of the plate 40 from the curved bafiies 50 and 5|, the reduction of velocity of the vapor and its change of direction aids any remaining liquid particlesto separate downward from it assisted by the force of gravity.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination of a drum, up-tubes for supplying a mixture of liquid and vapor to the drum, other tubes for separately discharging liquid and vapor from the drum, and means including a plurality of bailies for separating the liquid'and the vapor in the drum, each baflie having a plurality of spaced sections secured to the drum and means including sealing strips loosely supported on adjacent spaced sections.

2. In a mercury boiler, a drum, a conduit for supplying a mixture of liquid and vapor to the drum, a vapor discharge conduit connected to the drum, and liquid vapor separating means disposed within the drum and comprising a baffie having a plurality of slightly spaced separate sections welded to the drum and flexible sealing strips connecting adjacent bafiles.

ORLA L. WOOD.

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