US2781029A

US2781029A - Feed water heater

Info

Publication number: US2781029A
Application number: US355752A
Authority: US
Inventors: Kolling Johann
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1953-05-18
Filing date: 1953-05-18
Publication date: 1957-02-12
Anticipated expiration: 1974-02-12

Description

Feb. 12, 1957 Filed May 18, 1953 a 2 sheis-sneet' 1 32 50 27 rm 5/ P f /48 I l 7 F l G. 1 INVENTOR ATTORNEY Feb. 12, .1957 J, KOLLING 2,781,029

FEED WATER HEATER Filed May 18, 1953 2 Sheets-Sheet 2 INVENTOR gfohazm Jfollz'ng ATI'ORNEY United. States Patent Application May 18, 1953, Serial No. 355,752

liclaim'; ((31.11224-44'1) Thelpresent' invention .relates' to heat exchange appar'a tus, and" more particularly, to' app aratus' for' h'eatingffeed' liquidsupplied'to a vapor generator;

In the 'generation and .superl'leatin'gjof a vapor, suclijasj steam, itis'customtiry'to preheat the reeauquta'bere e introduction into the circulatoryisystem of the vapor gen: erator; In the field of steam gneratioh, feed water heaters, ec'onomizersland. other heat exchange apparatus" are customarilyfused; It'lias' also been proposedth'at thefe'e'd water leaviiigth'e economiier' section'of'a vapor" generathig unitwould "be. passed thr'ough heat exchange tubes disposed in the steam space of 'the' steam and water drum; Unfortunately;the use of suchheateXchan'geele ment'sfinsteam and-water dfums' has neces'sit'atedfthe provisionofspecialfit'tings' for the. indirect heate'r to avoid thermal stresses in thethi'ck waliof'tlie ste'ain and'watr drum. Were ssuch: heat iexchangeselements -to bei located within the drum-accessibilitydormaintenance and repair work would be hindered.

In the presentinvention "the *satriratedkteam :prbaneeu lay-the steanr generatoris' usedf inipartjito effectheating ofth'e feed waterr Thisis 'accomp'lishedby indirecthe'at exchange means positioned externally adjacent the steam and water drum and connected therewith, with the steam condensate resulting from the heat exchange utilized as a source of spray cooling medium in a spray type superheated steam attemperator, or for other useful purposes.

The various features of novelty which characterize my invention are pointed out with particularity in the claim annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described an embodiment of my invention.

Of the drawings:

Fig. 1 is a side elevation, partly in section, of a steam generating unit incorporating the present invention, and

Fig. 2 is an enlarged view, partially in section, of a portion of the apparatus shown in Fig. 1, taken on the line 2-2 of Fig. 1.

As illustrated in the drawing, the present invention is applied to a steam generating unit of known type. However, it will be understood that the present invention is not limited to heat exchange in a steam generator but can be utilized in any type of vapor generating unit where a liquid is converted to a vapor by the application of heat to the liquid and the vapor.

In the illustrated embodiment of the invention, a known type of steam generator is utilized to transfer the heat generated by the combustion of a granular solid fuel into water to produce superheated steam. The solid fuel is burned in cyclone type burners 11, such as disclosed in U. S. Patent 2,357,303. The cyclonic burners are water cooled by steam generating tubes in the Walls thereof which are connected into the circulatory system of the steam generator. The products of combustion are delivered at high temperature by the cyclones 11 into an Pataeiea r e. is, 1357 2i upwardly elongated. secondary combustion. chamber 12 which iszlikewiseenclosed by water'cooled walls.

The productsof combustion leavin'gtthe secondary combustion :chamberpass over'a plurality of supe'rheating elements 13 positioned in the furnace'outlet passageway 14. Thereafter, the partially cooledproductsof combustion are directed'overthe tubular elements of'an economizer 1'5, andarepassedtoa stack (not shownyfor'discharge to. the, atmosphere. In many installations, the gases are passed through-a combustion airheater before discharge to the atmosphere." Referring particularly :to Fig} 1, feed or makeup water from 'external'fee'd water heaters and/or aerators are delivered 'toth'e inletiheader 1"6'of the economizer. 15. After passingthrough the economizer tubes, the fed 'water is delivered to an euuetueaar 17a1'1 dfdirecreate the heating means of the present 'inve'ritionbyfa conduit "18.; r

As hereinafter described, the feed water passingthrough' the conduit 1751 enters the" upper .end" of 1 a lar e diameter downoomer'flTwhich is connected with oneflend'of the steamand water drum"21of the vapor generator;'and 'dis-' chargesih'eatedfeed 'water'to-the" lower header. 22: At least two 'downcom'ers' will .be usedih the circulatory systein of. ttfe unit; but *o'n'ly'fone islshbwninf the drawing The generatedirr the Wall tubesof the cyclone naces 'll' andof th'ese'condaryffurnacel2 i is deliveredto the 'ste'anfandwateri'drum 21; N Witmfi-rmuiirmaiute steam and: water" iss'eparatedby 'k'i-l'own means; such as showhiin'jU, Patent- 278 979Witli amajorpor onb'f' the steam "passing through a.plin'alitybfFsauirated 's't'a'rfi conduits.23 to a superheaterin'letlieader 2? The'satu ratedjsteamfp asses through thezmultipledoops 'of the first stagefZS'pf tlie superh'eaterfand is'discharged to"'an"outlet header 23 Thereafter, thef'superheatedfiteaniisipassed' througha'rr attemperator 27 whe'rein th esteanr'isfcooledf as 'r'equired, by spray attemperatiofwith cooling "water: The attemperated steam is thereafter delivered to an inlet header 28 of a second stage 29 of the superheater 13, with the superheated steam discharged from the loops thereof to an outlet header 30 and thence to a point or points of use.

As shown in Figs. 1 and 2, the downcomer 20 projects above the steam and water drum 21 an appreciable distance to provide a steam space 31 therein. Some of the saturated steam from the drum 21 passes through a row of conduits 32 to the upper end portion of the downcomer. The drum 21 is also connected with the downcomer 20 by means of a row of tubes 33 which open to the downcomer below the level of the drum 21. With both the steam and water spaces of the drum 21 connected with the downcomer 20, the water level within the drum will be substantially at the same level as the water level 34 in the downcomer.

The feed water delivered to the downcomer through the conduit 18 enters a distribution chamber 36 in the top of the downcomer which is separated from the steam space 31 by a tube sheet 37 and is in turn connected with the upper ends of and opens to a tube bundle 38 inserted in the upper end portion of the downcomer. The tubes in the tube bundle are preferably of small diameter to provide an extensive heat exchange area, and are thin V walled since the pressure difference between the steam and water is slight.

The tubes of the tube bundle 38 are extended downwardly through the upper portion of the downcomer to a position spaced above the water level 34. A lower tube sheet or diaphram 40 embraces the lower end portions of the tubes of the tube bundle at a position upwardly spaced from the discharge ends 41 of the tubes. The diaphrarn 40 is provided with a cylindrical member 42 extending upwardly along the exterior side of tube bundle. The upper end of the cylinder is provided with a tube sheet 43,

through which the tube bundle extends, and an upwardly spaced domed condensate deflector member 44. The annular space 45 formed between the wall of the downcomer 20 and the cylinder member 42 provides a steam condensate collecting chamber for the condensate resulting from heat exchange between the saturated steam and the feed water passing through the tube bundle '38.

The condensate collecting in the annular space 45 is withdrawn through a pipe 46 by a pump 47 which discharges the condensate through a pipe 48 into the attemperator 27 for atomization in the form of a spray so as to control the temperature of the steam delivered by the superheater. It will be appreciated that the condensate collected in the annular space 45 of the downcomer 20 will be of a high degree of purity. It is within the scope of the present invention to utilize this relatively pure water for steam washing processes, as well as for attemperation of the superheater steam.

Under some conditions of operation the feed water added to the steam generation will not be sufiicient to supply enough condensate through the pump 47 for steam attemperating purposes. Under such conditions additional water is supplied to the attemperator directly from the feed water supply. This is accomplished by admitting feed water into the pipe 48 through a branch pipe 50, with the flow therethrough regulated by'a valve 51.

While it is recognized that the condensate will be at a pressure generally corresponding with the pressure within the steam and water drum, the pump 47 is provided to increase the pressure of the condensate for use in the atomization of the water for attemperating purposes;

It is within the contemplation of this invention to omit the diaphragm 40 and to discharge the condensate resulting from the heat exchange in the upper portion of the downcomer into the feed water.

In operation, the heated feed water passing from the economizer 15 is further heated in the upper portion of the downcomer 20 by heat exchange with saturated steam from the drum 21. The thus heated feed water passes directly to the downcomer circuit of the vapor generating 4 unit. The steam condensate obtained by the heat exchange in the downcomer is utilized as a source of spray liquid in the attemperator 26. Advantageously, the condensate is of high purity commensurate with the purity of the steam delivered to the superheater's.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form and mode of operation of the invention now known to me, those skilled in the art will understand that changes may be made in the process without departing from the spirit of the invention covered by my claim, and that.

certain features of the invention may sometimes be used to advantage without a corresponding use of other features. a

What is claimed is:

The combination with a steam generator having an upper steam and water confining drum, a multiple stage superheater receiving steam from said drum, said superheater having an interstage steam attemperator, said steam generator having a circulatory system including at.

least one large diameter downcomer, the upper end portion of said downcomer extending above the steam and water drum of said steam generator, separate means connecting the steam and water spaces of said drum with said downcomer and forming a steam space within said downcomer, a plurality of tubular heat exchange elements positioned in the steam space of said downcomer, a diaphragm embracing the lower end of said tubular heat ex-' change elements in the steam space of said downcomer, means for passing feed water through said tubular elements to discharge into said downcomer, and means for removing condensate from the steam space of said downcomer above said diaphragm and discharging said condensate into said steam attemperator.

Schellens et a1. June 9, 1931 Karassik Dec, 17, 1940 Brueggeman Oct. 30, 1923