US2578831A - Forced circulation steam generator - Google Patents

Description

,Dec. 18, 1951 w. s. PATTERSON FORCED CIRCULATION STEAM GENERATOR Filed Sept. 4, 1947 n n n n n INVENTOR.

Word 8. Patterson BY Auri a/bur flr ai hgy Patented net. 18, 1951 FoRcEni' omciiizzrrioN STEAM GENERATOR Ward S. Pattersom chappaqua, N. YJassignor to CoinbustioncEligineering Superheater, Inc.',' a corporation of Delaware Applieation seibtemlier 4, 1947, Serial'NoI 77231195 This invention relates-"to apparatus for gener atingsteam and particularlytoa steam genera-' tor in which thereis acontrolld forced=circu="-- lation of the fluid through the steam generating tubes.

D form'of the invention,

In steam generators constructed to operatein Figurei is a Section takeii'on"line-44 of F this manner it is essential to distribute the water ure 1 showing how the steam"*generatorsfheat to the steam generating tubesin'sufii'cient quan absorbing tubes" are arranged for parallelflowtity so that each of the tubes;which'are' arranged" therethrough of the liquid to be vaporized. for parallel water flow therethrbughiwill"be"sufii=' Fig. "5 is a longitudinalsection throughthe ciently cooled by the water to protect'it against steam" generatorfs distribution header' takem'on overheating and consequent"damageunder-"all line 5- 5 'of-Figs."2 and 3 and'showing 'howthe ratesof steaming. herein-disclosed 'screening imeans' extend 'l0ngif A preferred way of accomplishing'such'detudinally of theheader to span-"a multiplicity sira'ble distribution of 'waterto' all" of the tube" Sta'm generating tube ends? circuits which are connected'ior' paraller'water Figures 1 and illustrate an "embodimentbf flowtherethrough to a manifoldordistribution' the invention-arranged for steam generation. header, has been to provide 'orificesor-resistances The ste g illustrateficbmprises'a fur? at the entrance to each-"of thetubes. Th'eseori-- nace chamber! within which-"'fue1-is"burnewby" fices are of smaller diameterthan' the "tube, the -meanss'u0h as an oil'burner"2' arrangedtdde diameter being chosen'to'present a substantial liver oil for combustioninthiurnaceinfi Well?- resistance to the flow of water? variations in'" kn wn m r. he i 3*h v g"its atin the latter resistance thenhave-a reduced-in- Surface Within the: fl p fluenceupon the total resistance oforifie and Zontal cy ical steam and water" druinrs to tube and consequently upon the-flow" of water- *which Water may be supplied from any suitable" through the tube as governed by 'theoriflce, source" throughxfeed-pipe '6 and steammaybe It is essential then that the-orifice'remain'unwithdrawn throughp p "11"" obstructed by foreign matter-suchas'scaieparti The heating surface 4 withini'the'boilercom cles -01" sludge, during operation *because'the D E m ipli i y' f p al'l' y-a ra d tubes amount of water flow'through the tube and the- 4 connected to a commondistribution header 8 tubes safety depend upon it; Heretofore' screens and passingthence upwardly along'a wall of the or strainers have been provided'with'in' thg'diSJ furnace-l and theme" iI1baCk=9 nd-f0 t 'D SSe tribution header at each of theorifidesywhbs upwardly through theupperportionbfthe fur= screen openings are smaller thanth'e' -orificso' nace to connect to the steam'rand wate'rdrum as to stopthe flow of foreign-matter to the0r1'- 5. "A downcomer 9"is conneoted'at itsuppe'rfend' fice which would otherwiseobstruct'it. to thebottomportion of drum-5 and'at itsiower-"i It has been found from experiencethat'it is end o the inlet of 'p p impossible to insure againstpredominant'segre+ p p is connected at its "dischargeflendtodis fi gation of such foreign matter into some of the tribution header 3 by -l Tli' pu p distribution headers and orteirtc a'lim'ited ioca- 401"! is driven as y' i ot shqwny and cirs-t tionin one of the headers',asforexaiiipleiadjatk (Hates the d m intoi'healdef cent-the ends r near th middlgbf fha'd 'fi. g thence through allof the'tubesii'fl" and'b'ac'k "into pending upon new conditions in the headeLI'THe drum An Ofitak? mm/es thaproductsfif amount of the foreignj'm-atte'rorfSolidihatiial combustion from the furnace?v in circulation within thel steaniigeriei'ator may- 46 In Order to insure propefdistribufibh"Of be insignificant yet. sufficient," when segregated Watgr amongau of the tubes 9 theheatin'gflsurfi at one location within a header, to cause trouface w h areconnectedin'parallelbetween"" ble. Such segregation has resulted in a local orlthe-header a t 1t fi l p m fice' strainer becoming plugged and failure-.of-the m such," as f Fag, PP Y ig. associated tube from lack of water and-.overh eat- 13) o i ii t i h fl w-R We? f 9? ingentranceend of each tube," The present inven- It is an object of this invention to provide an n is concgmed w antimgmved F t improved strainer within a distribution header maintaining these orifices m proper operating condition'by protectin'g'them fromforeignmate Whlch the -F F rialin the water-which might obstructth'ein."

Refemmg -P the drawingsrlflustratmamra" Figs.'2 and 3'show' twopreferred-"embodiments" e e em'bodlm'ents 0f thejinventloni of 'my invention' as arrangedwithin" the distri 1 1 S a dl m twrepresentation1oft; I bution'header 8 and 8 respectively? In Fig.' 2thefo d u t tea enerator.e: ,7 distributionii'eader s'risrectangciarin'formma Fig-. -;2 ant-enlarged mrossizseetlomthroughiia iioizing water supply tubes or pumvzcorm'ecti he sr 2 distribution' headerof Fig. '1 showing one form" of the invention? Figf3 is an enlazgedwiross section-througma distributionheaderof Figf-"ll showing another from circulation pump Ill as shown in Fig. 1. The steaming or boiler tubes 4 are connected to the header as by welding-and are in alignment with a cylindrical opening l4 through wall l5 of distribution header 8'.

A semi-cylindrically shaped strainer I6 is mounted within the header 8 and comprises a semi-cylindrical plate I! welded to a fiat closure plate [8 extending across the diameter of the strainer 16'. Arranged centrally and longitudinally of the closure plate 18 are orifices I3 mounted into holes l9 provided in said plate longitudinally thereof at spaced intervals. The orifice structure comprises a tubular portion 20 having an outside diameter suitable for mounting in hole l9 in plate l8 and having an end portion 2| within which is the orifice opening I3. The cylindrical plate I! of strainer 16 is provided with a multiplicity of apertures 22 each of which is smaller in diameter than the diameter of orifice hole l3. Preferably the sum of the areas of said perforations is at least 75% of the area of the unperforated strainer tube containing said orifices.

This strainer I6 is mounted on header wall l5 by means of stud bolts 23 projecting'from said wall and bands 24 which bear against the strainer to urge it toward the header wall IS. The strainer I6 is so placed that the orifice holes align with the respective ends of the tubes 4. Preferably a soft gasket 25 may be placed between the plate l8 of strainer 16 and the wall l5 of header 8'. Should the gasket 25 be omitted the strainer It would move into contact with the header wall l5 and the cylindrical portion 20 of the orifice would enter the hole [4 provided within the header wall I5 in alignment with tubes 4. The diameter of the strainer I6 is such that it may be removed through the hand hole 26 at the end of the header 8.

The strainer of Fig. 3 (wherein like reference numbers indicate like parts as in Fig. 2) is in all essentials similar to the strainer in Fig. 2 excepting that this Fig. 3 strainer l6 now comprises a complete cylinder structure. A multiplicity of spaced-apart nozzles 21 are Welded on to the strainer, one opposite each of the holes M in the header wall l5 (shown inFig. 3 as being curved). The cylindrical portion 20 of the orifice structure is mounted into these nozzles and projects beyond the end of the nozzles to provide a seat for a possible soft gasket 25. Should the gasket be omitted the cylindrical portion 20 will telescope into the hole M in header wall l5 and the outer face of nozzle 21 will rest against the inner face of the header wall 5. The support of the strainer in Fig 3 is identical with the support of the strainer shown in Fig. 2.

The strainers l6 and I6 of both the Fig. 2 and Fig. 3 designs may be made several feet long or any length that maybe conveniently handled (see Fig. 5) Only two or three clamps per strainer are required so that only a few hand holes 28 will be required in header walls opposite to the strainer. With my improved strainer but eight or ten strainers are all that would be required for a large-sized steam generating unit when compared to the present requirement of three hundred to four hundred individual strainers adjacent each tube end. Furthermore, but twenty or thirty hand hole openings located opposite each strainer support will take the place of three hundred to four hundred closure plug openings as now used whereone closure is requiredopposite theendofeachtuba. V .7.

With my improved strainer each orifice may receive its water through the adjacent apertures in the-strainer or, should these adjacent apertures be plugged by foreign matter, said orifice could receive its water from apertures opposite the remaining orifices included by said strainer. In this manner the danger of obstructing one orifice with its individual strainer is overcome. 1

Furthermore, it is possible with my improved arrangement of strainer to provide two pressure taps in each header, one connected to the space outside of the strainers and the other to the space inside of the strainers, so that a pressure drop across the strainer may be noted which will give an indication of the degree of plugging. This is an improved feature for a boiler unit operating with high makeup of treated (non-evaporated) feed water.

While the preferred embodiment of my invention has been shown and described, it will be understood that changes in construction, combination and arrangement of parts may be made without departing from the spirit and scope of the invention as claimed.

What I claim is:

1. In a steam generator having a steam and water drum and a plurality of steam generating tubes exposed to the heat of the products of combustion from a furnace, a distribution header connected to the inlet ends of the aforesaid plurality of tubes for flow of water therethrough in parallel circuits, the discharge ends of said tube circuits being connected to the steam and water drum; resistance means within each circuit disposed at the said inlet end of each tube that is connected to said distribution header and in fluid-flow relationship therewith; screen means mounted within the header to prevent foreign matter from obstructing the resistance means, said screen means comprising a tubular perforate element extending longitudinally of the header to span a multiplicity of the steam generating tube ends and forming an envelope surrounding an open and unobstructed passage from any open portion of said tubular perforate element to any and all of said resistance means; means connecting each tube inlet end and its resistance means with the inner or discharge side of said tubular perforate element so that only the drum to the header through the aforesaid tubular perforate element and tubes back to the drum; and connections from the steam and water drum to said forcing means and from said forcing means to that portion of the distribution headers interior which surrounds the outer or inlet side of said tubular perforate screening element.

2. In a steam generator having a steam and water drum and. a plurality of steam generating tubes exposed to the heat of the products of combustion from an associated'furnace, a distribution header connected to the inlet ends of the aforesaid plurality of tubes for flow of water therethrough in parallel circuits, the discharge ends of said tube circuits being connected to the steam and water drum; means forming an orifice within each circuit said means being disposed adjacent the said inlet end of each tube and in fluid-flow relationship therewith a perforate p76 Wall element mounted within theheader to prevent foreign matter from obstructing the said orifice means, said perforate wall element having an inlet side and an outlet side and extending longitudinally of the header to span a multiplicity of the steam generating tube ends at said wall elements outlet side and being adapted to form an unobstructed passage to any and all of the aforesaid orifice means from any open portion of said perforate wall element so that only water which has passed through the perforate wall from its inlet side to its outlet side can be admitted into the aforesaid orifice for each tube; a pump for forcing a flow of water through the circuits in direction of from the drum to the header through the perforate wall and tubes back to the drum; and connections from the steam and water drum to the pump inlet and from the pump discharge to that portion of the distribution header which is on the inlet side of said perforate wall element.

3. In a steam generator having a steam and water drum and a plurality of steam generating tubes exposed to the heat of the products of combustion from a furnace, a distribution header connected to the inlet ends of the aforesaid plurality of tubes for flow of water therethrough in parallel circuits, the discharge ends of said tube circuits being connected to the steam and water drum; resistance means within each circuit disposed at the said inlet end of each tube that is connected to said distribution header; an access hole in an end of said header; screen means mounted within the header to prevent foreign matter from obstructing the resistance means and constructed to be removable through said hole, said screen means comprising a tubular periorate element extending longitudinally of the header to span a multiplicity of the steam generating tube ends; means connecting each tube inlet end with the inner or discharge side of said tubular screen so that only water which has been passed through the screen perforations can be admitted into the said resistance means for each tube; means for forcing a flow of water through the circuits in direction of from the drum to the header through the said tubular screen and tubes back to the drum; and connections from the steam and water drum to said forcing means and from said forcing means to that portion of the distribution header interior which surrounds the outer or inlet side of said tubular screen element.

4. In a steam generator having a steam and water drum and a plurality of steam generating tubes exposed to the heat of the products of combustion from a furnace, a distribution header connected to the inlet ends of the aforesaid plurality of tubes for flow of water therethrough in parallel circuits, the discharge ends of said tube circuits being connected to the steam and water drum; resistance means within each circuit disposed at the said inlet end of each tube that is connected to said distribution header; means forming a fluid-flow connection between each tube inlet end and the said resistance means thereat; an access hole in an end of said header; screen means mounted within the header to prevent foreign matter from obstructing the resistance means and constructed to be removable through said hole, said screen means comprising 7 a perforated tubular member extending longitudinally of the header to span a multiplicity of the steam generating tube ends and having an inner or discharge side connected with all of said tube end resistance means to establish unobstructed communication therewith; means for forcing a flow of water through the said plurality of circuits in direction of from the drum to the header through said perforate tubular member and tubes back to the drum so that only water which has passed through the tubular member's perforations can be admitted into the said resistance means for each tube; and connections from the steam and water drum to said forcing means and from said forcing means to that portion of the distribution header interior which surrounds the outer or inlet side of said perforate tubular member.

5. In a forced circulation boiler, the combination of a steam and water drum; a distributing header; a plurality of heat absorbing tubes for the generation of steam from water having outlet ends communicating with said steam and water drum and having inlet ends connected to a row of openings in said distributing header; flow restricting means associated with each of the said inlet ends of said tubes; forced circulation means having a suction side connected to said steam and Water drum and a discharge side connected to said distributing header; and a perforated division wall within said header disposed in a position opposite the said row of tube inlet openings and interposed between the discharge side con-' nection of said forced circulation means and the said row of tube inlet openings whereby water recirculated from said steam and water drum by way of said circulation means can enter any one of said heat absorbing tubes by passing through any one of the perforations of said headers division wall.

6. Ina steam generating boiler, the combination of a steam and water drum; a distributing header; heat absorbing tubes for the generation of steam from water having discharge ends connected to said steam and water drum and having inlet ends connected to a row of openings in said distributing header; flow restricting means at the inlet end of each of said tubes; forced circulation means having a suction side connected to said steam and water drum and a discharge side connected to said distributing header; and a perforated strainer member within said header extending along the row of tube inlet openings from end to end thereof and interposed between the discharge side connection of said forced circulation means and the said row of heat absorbing tube inlet openings whereby Water recirculated from said steam and water drum by way of said circulation means can enter any one of said heat absorbing tube inlet openings by passing through any one of the perforations of said header's strainer member.

. WARD S. PATTERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 188,144 Jennings Mar. 6, 1877 248,573 Burkhardt Oct. 25, 1881 1,988,659 La Mont Jan. 22, 1935

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