US2282777A - Foam inhibitor apparatus for boilers - Google Patents

Description

May 12, 194 L. o. GUNDERSON FOAM INHIBITOR APPARATUS FOR BOILERS Filed March 15, 1940 Patented May 12, 1942 FOAM INHIBITOR APPARATUS FOR. BOILERS Lewis 0. Gunderson, Park Ridge, 111., assignor to Electro-Chemical Engineering Corporation, Chicago, Ill., a, corporation of Delaware Application March 15, 1940, Serial No. 324,149 8' Claims. (o1.'122 459) This invention relates to the elimination of a sustained level of light water or foam in the vicinity of the steam outlet of an operating steam boiler.

More specifically the invention relates to a foaminhibitor plate mounted flatwise in a locomotive boiler to extend from near the fire box of the boiler to a point well beyond the steam dome and at a level above the flues of the locomotive but beneath the normal water level therein. The plate is mounted in spaced relation from the boiler shell so that it defines a localized nonsteam-generating course in full communication around the entire perimeter thereof with the main body of boiler water in the boiler.

While the invention will be hereinafter specifically described in connection with locomotive boilers, it should be understood that this is only an example of one use of the invention and that the foam inhibiting apparatus can be used in any type of steam boiler.

According to this invention a metal plate is horizontally mounted above the rear ends of the fiues in a locomotive. The plate extends forwardly from the locomotive fire box to a point well beyond the steam dome or steam outlet of the boiler. 'The edges of the plate are spaced from the boiler shell so that the top of the plate is in full-communication with the main body'of boiler water. The plate is mounted at a level in the boiler slightly beneath the normal water level and serves to define a somewhat insulated non-steam-generating course along the top of the main body of boiler water.

Since the hottest part of a locomotive boiler is around and over the fire box, water will fiow over the plate in a forward direction under'the steam dome or outlet. Steam bubbles generated under the plate cannot rise into any foam or light water on the top of the boiler water in the vicinity of the steam outlet because the same must travel under the plate to the edges thereof where they will collapse in the non-steam-generating area above the plate.

Likewise, bubbles emerging from the fire box end of the boiler will flow forwardly over the plate and will collapse after traveling a short distance along the non-steam-generating area. As a result, the steam space of the boiler above the plate will be retained substantially free from light water or foam development between the fire box and the steam dome. The plate impedes therising of steam bubbles formed therebeneath and a feature of this invention includes the directing of these bubbles to the side edges of the plate away from the non-steam-generating zone formed above the plate. The bubbles thus must travel along a longer path before they are released at points spaced from the steam outlet. This increased travel depresses foam development and has the same effect as permitting the bubbles to rise an appreciable amount into the steam space before spilling into a trough having an inlet above the water level in the boiler.

Since the plate keeps the steam space clear for passage of steam from the fire box end of the boiler, where most steam is developed, to the steam dome, no high steam velocities are created tending to entrain foam or moisture therein as it passes to the steam outlet.

Another feature of the invention includes the spraying of feed water or make-up water into the boiler at a point above the plate where it can be readily commingled with the water flowing forwardly over the plate.

If desired, according to the invention, the boiler can be blown down automatically whenever foam development on top of the plate reaches a predetermined level.

It is, then, an object of the invention to inhib-it foam in operating steam boilers by mounting a plate fiatwise in a boiler'adjacent the steam space thereof but below the normal water vlevel therein. I Y

Another object of the invention is to provide a foam inhibitor plate in a steam boiler of the locomotive type capable of effectively preventing the rise of steam bubbles into foam formation on the boiler water in the vicinity of the steam outlet from the boiler.

Still another object of the invention is to provide a localized non-'steam-generating course in the vicinity of the steam outlet of a boiler that is in full communication with the main body of boiler water around the entire perimeter thereof.

. A further object of the invention is to inhibit foam and moisture entrainment in steam leaving a locomotive boiler by means of a comparatively fiat plate mounted horizontally in the boiler just below the normal water level therein and extending from the fire box to a point beyond the steam outlet with the edges of the plate spaced from the boiler shell.

Other and further objects of the invention will be apparent from the following detailed description of the annexed sheet of drawings, which discloses a preferred embodiment of the invention in a locomotive boilerr On the drawing: A

' Figure 1 is a'fragmentary side elevational view with parts broken away and shown in vertical cross section, of a locomotive boiler equipped with a foam inhibitor plate, automatic blow-off devices, and feed water spray device according to this invention.

Figure 2 is a fragmentary vertical cross-sectional view, with parts shown in elevation, taken along the line IIII of Figure 1.

Figure 3 is a fragmentary bottom plan view of the foam inhibitor plate, taken along the line IlIIII of Figure 2.

As shown on the drawing: In Figures 1 and 2, the reference numeral I designates generally a locomotive having the usual boiler shell II defining. aboiler course I2.

Plates I3 are mounted inside of the boiler shell II to define a fire box I4 at the rear end of the boiler. Fire tubes I5 extend from the firebox I4 through the boiler course l2 beneath the surface of the boiler water B. W. therein. The nor mal level of the boiler water B. W. is, as usual, maintained above the top plate I3. of the fire box I4. A steam space S S. is thus provided in the top of the boiler course I2 above the boiler water B. W.

The usual engineers cab I6. is mounted around the rear end of the boiler.

The boiler shell H has an opening H in the top thereof enclosed with a cover. I8 providing the usual steam dome I9 above the top of the boiler. The steam dome I9 is spaced forwardly of the fire box Mas shown in Figure 1.

A steam outlet pipe or dry pipe extends upwardly into the steam dome I9 and has the open top end thereof spaced beneath the top of the cover I8. The dry pipe, usually extends forwardly along the boiler course I2 to the superheater equipment, operating cylinders, and the like appurtenances of the locomotive for supplying steam thereto. 7

According to this invention an elongated imperforate metal plate 2|..is suspended fiatwise in the boiler course I2 by means of straps 22 secured inside of the boiler shell I I. The plate .2 I, as shown in Figures 1 and 2, is suspended above the fire tubes I5 but beneath thev level of the boiler water B. W. The plate is preferably mounted about level with the top of the fire box I4 and extends from the fire box to a pointbeyond the steam dome I9 as shown in Figure l.

As shown in Figure 2, the plate 2| hasthe side edges thereof parallel with thesides of the boiler shell and in spaced relation therefrom. A space of from siX inches to one foot between the edges of the plate and the boiler shell is desirable. Since the opening H in the top of the boiler is in the longitudinal center of the boiler shell, the plate 2| will thus be disposed beneath this opening and will extend therebeyond in all directions as shown in Figures 1 and 2.

The plate 2| is preferably slightly sloped down toward a central longitudinal line 23 thereof so as to provide two inclined leg portions 2| a. and 2 lb from thedepressed center line 23 to the edges of the plate. The leg portions should preferably slope about 2 to 3 from the horizontal.

Lateral baffles 24 are secured along the underside of the plate in the form of chevrons with the pointed ends or vortices facing the fire box I4 and with the sides thereof slanting outward to the sides of the plate. at an obtuse angle.

The baflles will serve to direct steam bubbles 25 generated under the plate toward the edges of the plate where they can rise 'to'the top of the boiler water B. W. as shown inFigjures 2 and 3. This will prevent formation of steam pockets beneath the plate. The baflles are preferably quite shallow as indicated in Figures 1 and 2, so that they will not interfere with the normal circulation of water in the boiler at points spaced below the plate.

Since the hottest portion of the boiler course is adjacent and above the fire box I4, the normal flow of water in the boiler is toward the front end of the locomotive. Since the plate 2| is about on the same plane with the top of the fire "box, water flowing forwardly from the top of the fire box passes over theplate. The water area on top of the plate is a non-steam-generating zone since it is somewhat insulated from the fire tubes of the boiler.

Because foam F or light water develops first in the hottest portion of the boiler this light water and foam will likewise fiow forwardly over the plate and will rapidly collapse into solid water after having. traveled a short distance in the nonsteam -generating area. Steam bubbles are prevented from rising into any mass of foam formation on the boiler water and a sustained level of light water orfoam in the boiler in the vicinity of the steam dome is prevented. The bubbles emerging from the fire box to flow over the plate collapse after traveling at short distance and likewise the bubbles emerging from the sides of the plate collapse, so that the steam space in the boiler is retained substantially free from light water and foam between the fire box and the steam dome. The steam space is thus kept clear for flow of steam to the steam dome and high steam velocities are avoided such as would normally tend to entrain foam or moisture.

As indicated in Figure l, a foam level is not maintained above the plate 2| in the vicinity of the steam zone because the foam developed ,at the fire box end of the boiler collapses after it travels a short distance over the plate. As also shown in Figure 2 the steam bubbles developed under the plate are directed to the sides thereof by means of the baffles and will collapse on top of the boiler water at the sides of the plate.

The water under the steam dome is thus always maintained as solid water and since the water area above the plate receives the collapsed foam and light water it contains high concentrations of electrolytes and alkalies.

The feed water F. W. is sprayed into the boiler from a spray head 26 suspended in the steam space of the boiler from a feed pipe 21 projecting through the top of the boiler shell. The spray of feed water F. W. ejected by the spray head 26 is impacted downwardly on top of the water in the non-steam-generating zone above the plate 2| at a point where the foam and light water have collapsed. As shown in Figures 1 and 2, the spray head 26 is thus positioned spaced'from the rear of the steam dome IQ and above the longhtudinal center of the plate 2|.

The sprayed feed water intimately mixes with the water flowing over the plate and is rapidly heated by this water. A preheating of the feed water is effected before the same enters the main body of boiler water B. W. Likewise, since the water flowing above the plate contains a high concentration of electrolytes and. alkalies, the feed Water, being intimately mixed therewith, will effect a precipitation of scale forming ingredients.

At the same time the water hardening ingredientsof the feed water are sludged to effect a flocculation thereof. 1 v

Theintimate mixing of the feed water with the highly concentrated water in. the boiler will effect a rapid transition of the .pH value of the feed water to an increased pHv value thereby minimizing chances for adsorption ofv organic substances on dispersed matter in the water. This minimized'adsorption reduces foaming tendmay of the water finally supplied .t-othe' main body of boiler water and .inhibits formation of surface active substances. The feed wateris thus preconditioned.

If the feed water contains colloidal oil incor- I porated therein from the feed-water heaters, exhaust' steam injectors, pumps or other appurtenances, the concentrated water above the plate 2| will efiect a salting out-f the oil. This is caused by the electrolytes in the concentrated water. The oil will be simultaneously adsorbed or agglomerated in the flocculated alkaline compounds or precipitates being formed and is thus removed. 5 I

The feed water is supplied to thespray-head 26 through the pipe line 21 from a pump 28 mounted on the outside of the boiler. The pump 28'is fed from the pipe line 29 communicating withthe Water tank of the locomotive tender. Injectors, or other appurtenances, can'be embodied inthe line 29.

As shown in Figure l, a short electrode 30 'projects through the top of the boiler shell ll into the steam space of the boiler abovethe plate 2| at a point where the foam from the rear end of the boiler and the sides of the plate-reaches a collapsed condition as shown'in Figur 1.

A longer electrode 3| projects from the top of the boiler toward the plate 2|.near the rear end of the plate. This long electrode terminates below the short electrode 30 and is adapted to be contacted by foam F flowing over the plate 2!. The electrodes 30 and 3| are electrically insulated from the boiler shell I l.

A source of electric current such as a generator 32 is mounted on the locomotive and has one terminal thereof grounded On the boiler shell through a wire 33. The other terminal of the generator is connected through a wire 34 with a foam meter box 35 mounted in the engineers cab and having a multiple relay 36 therein. The wire 34 communicates with the relay 36 and the relay has one arm 36a. thereof adapted to establish contact with a wire 31 leading to the long electrode 3!. The other arm 36b of the relay is adapted to make contact with a wire 38 from the short electrode 30. Signal lamps 39 and 40 are also provided in the box 35.

When foam rises to a level sufliciently high to contact the electrode 3!, the electrode will be grounded through the foam to the boiler shell and an electrical circuit will be established through the wires 34 and 31 to close the relay arm 3Ba, light the lamp 39 and energize a wire 4! leading to a solenoid-operated air valve 42.

The air valve 42 receives compressed air through a supply line 43 and, when opened, supplies this air through a tube 44 to a sludge blowoff valve 45 communicating with the lower portion of the boiler. The valve 45 discharges into a pipe line 46 communicating with a steam sep-' to complete the circuit when the relay, arm 36:]. is closed.

Thus when foam reaches a predetermined level above the rearend of the plate 2|, the boiler is automatically blown down. -When the foam rises to a higher level and travels further forward in the boiler into contact with the short electrode 30, a circuit .is established toclose the relay arm 3% and light the top lamp' 40 thereby indicating to the engineer that the boilershouldv be manually blown down. If desired,-a top blow off can be used in place of the bottom blow off 45.

It should be understood'that the foam inhibitor plate of this invention need'not be used in connection with automatic blow oif' apparatus. Since, however, it isin full communication with the boiler water and forms somewhat of a localized water area thereabove having the foam producing substances concentrated therein, it is well adapted for'use in combination with automatic blow down equipment. 7

In difiicult operating periods when water must be conserved and the boiler cannot beblown because it inhibits foam formation in the vicinity of the steam dome. I

The collapsing of enhanced amounts/of foam and light water in the area on top of the plate 2| can be readily taken care of since the additional quantities of solid water thus produced are immediately recirculated back to the main body of boiler water. Flooded conditions over the plate are thus prevented. v

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted herein otherwise than necessitated by the scope of the appended claims.

I claim'as my invention: I

1. In a steam boiler having a steam outlet in the top thereof, a steam space for supplying steam to the outlet and a water space beneath the steam space, the improvement which comprises an imperforate foam inhibitor plate mounted fiatwise in the water space of the boiler under the steam outlet and adjacent to the steam space of the boiler to define an elongated nonsteam-generating course extending in the direction of major water flow in the boiler and submerged in the water space around the perimeter of the plate.

2. In a locomotive boiler including a boiler shell defining an elongated boiler course, a fire box in one end of the boiler shell, and a steam dome on top of the boiler shell in communication with the boiler course in spaced relation from the fire box, the improvement which comprises an imperforate foam inhibitor plate extending fiatwise along the boiler course and under the steam dome from a point'adjacent the fire box to a point forward of the steam dome and at a level beneath the normal water level in 3. In a steam boiler .having a water space, a steam space and a steam outlet communicating with the top of the steam space, the improvement which comprises an imperforate foam inhibitor plate submerged in the water space and extending in the direction. of major water flow in the boiler beneath the steam outlet, said plate having a depressed longitudinal central portion and legs sloping upwardly from said central portion into spaced relation from the boiler shell, and means for rigidly holding said plate in the water space of the boiler. V j

4. A foam inhibitor plate for steam boilers comprising a metal sheet adapted to be suspended in the water space of a boiler and having slightly inclined portions extending from a longitudinal center line thereof, and spaced baflles secured on the bottom of the sheet diverging from said longitudinal center line to the sides of the sheet.

5. A foam inhibitor device for steam boilers comprising a substantially flat imperforate plate, and chevron-shaped shallow bafiles secured on the bottom of the plate in spaced relation, said baffles having the convergent ends thereof aligned along the longitudinal center of the plate.

6. In a locomotive boiler including a boiler shell defining an elongated boiler course, a fire box in said shell adapted to be surrounded by water in said boiler course, fire tubes extending forwardly from said fire box throughthe boiler course, and a steam dome on the top of said shell forwardly of the fire box, the improvement which comprises a foam inhibitor plate suspended flatwise from the boiler shell in the boiler course at a level beneath the normal water level in the boiler, said plate extending from a point in closely spaced relation to the first box to a point forwardly of the steam 'dome' and being spaced from the boiler shell to be in full communication with the main body of boiler water around the entire perimeter thereof, and a spray feed water device suspended from. the top of the boiler shell above said plate to impact feed wateron top of the water flowing over the plate intermediate the ends of the plate.

7; The method of controlling a steam boiler which comprises flowing light water and foam from'the hottest portion of the boiler along a non steam generating area submerged in the boiler water and extending beneath the steam outlet to collapse the foam and light water before it reaches the outlet, and diverting steam bubbles in the boiler water under said area to points spaced from the outlet and thereby' maintain a clear steam channel for flow of steam to the outlet. 7

8. The method of controlling a steam boiler which comprises flowing boiler water and any foam and light water developed thereon from the hottest portion of the boiler along a nonsteam generating area submerged in the boiler water and extending beneath the steam outlet to collapse the foam and light water before it reaches the steam outlet and to prevent generation of additional foam and light water from the thus flowing boiler water, diverting steam bubbles in the boiler water under said area to points spaced from the outlet for maintaining a clear steam channel for flow of steam to the outlet, and introducing feed water into the-nonsteam generating area in accordance with the requirements of the boiler.

LEWIS O. GUNDERSON.

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