US1753589A - Waste-heat boiler - Google Patents

Description

April s, 1930;

' Q1, E. BELL WASTE H EAT BOILER Filed oct. 1. 192s INVENTOR fl//l//l/ 4 ATTORNEY 30l my invention.

Patented Apr. 8, 1.930

" `UNITI-:D s'ra'rss PATENT oFFicE Y v JOHN E. BELL, OF BROOKLYN, NEW YORK; LOLA R. BELL EXECUTE/IX OF vSAID JOHN E.,BELL, DEGEASED l WASTE-HEAT BOILER Appncatiqn filed october 1,1923. `serial 1ro. 665,762.

My present invention relates to waste heat boilers for utilizing the available heat in hot gases heavily laden with dust discharged from industrial furnaces, and was primarily 5 devised, and is especially adapted for use inV a plant in which the boiler heating gases are those issuing from rotary cement kilns. The general object of my invention is to provide an improved arrangement of the lheatinggas flues and passageswhereby the problems due I to the presence of cement or other furnace l dust in heating gases are solved in a novel and acterize `my inventionare pointed out with particularity inthe claims annexed to and forming a part 'of this specification. For a better understanding of the invention, however, its advantages and specific objects attainedW with its use, reference should be had to the accompanying drawings in which I have illustrated a preferred embodiment of Of the drawings heat boilers; and Figa@ is a section on the line 2-2 of Fig. 1. In the drawings, I havek illustrated the use of my inventionv in a waste heat boiler system for utilizing thehot gases from a battery of rotary cement kilns A each of'which nor- 40 mally discharges its hot gases into a common -bus flue D. In accordance with the usual practice' seats or guideways C are provided for damper or valve arrangements'for closving each of the connections D from the various kilns A to the fiue D when necessary,

and a stack B is provided f or each kiln A being connected thereto only when the corresponding connection D is closed. Associated with the flue Dare one or more, and in 50. practice .usually the latter, `waste heat'boilers F, each boiler being connected to the flue D by an individual Vflue connection E having provisions, including damper rguideways or seats E2,by which the boiler may be disconnected from the flue D when this is necessary Vor desirable. `for the spent heating ,gases which is connected Y to suitable draft creating means shown as Each boilerF has an outlet comprising an individual exhaust fan G 4and stack H ,for each boiler. described the apparatus illustratedis of a conventional'type well known and inV general use. l

Each ofthe iiue-connectionsE `by which heating gases `are passed to the VboilerF is arranged, in accordance with the present invention, to pass the heating gases into the top of the corresponding boiler housing. As shown', the'boilers are located alongside the flue D with the top of each boiler housing at a level vbut little above that of the top of the flue, and each flue connection E comprises an uprising portion leading away 'from-the flue D, a horizontal portion in which the damper guideway E2 isv formed, and a down?-Y comer portion E opening toa heating gas inlet F2 in the top wall of the boi-ler housing. While someof the advantagesof the invention are obtainable with various types of boilers, I prefer to-employ a boiler of the-- o horizontal water tube, cross drum type illus- Fig. 1 is a diagrammatic plan view of a' portion of a cement kiln plant including waste trated. The boiler shown comprises two generally similar lbanks I and I of water tubes In so far as above-f .f1

connected tothe usual headers I2, and each upper header is connected to the subadj acent header'by nipples I8. Above the lower headerof the topbank of tubes Iis llocated a steaml and water drum I4, which is connected to the upper end of the top front header by horizontal circulating tubes I", which are immediately beneath the dat top wall F of the boiler housing in which the heating gas inlet F2 is formed at the side or end of the boiler remote Icatesat its lower end with the outlet flue 'F3 n auf running to the corresponding exhaust` fan Gr, and a dust pocket F4 is formed in the boiler setting to receive the dust settling out of the gases in passing through the first and second passes of the boiler. Suitable provisions illustrated in part, but which it isnot necessary to described herein, are provided .for 'reniovt ing dust collecting in the pocket F4.

Advantageously a superheater K is placed atl theboiler heatiiigf gas-inlet F'2 infront off" located immediatelyr above-the flatk top wall F of the boiler housing.V rllhe'wall F then. forms a platform for Workmen engaged-ini replacing the superheater tube elements, or removing dust accumulations andV incrustations from the superheater, as by meansloi.

steam lances-or pokers. The accessibility 0iv the superheater for cleaning andi tube replacement ust referred to,.constitutes one. of. the practically importa-ntl characteristics, of the invention. v

In' passing dustladen: heating gases down into a tube bank. there is a tendency for the dust accumulation' tofbe' heaviest at the top of the bankwherethe-heating gases' first contact. with the tubes and: with thepresent invention this initial largey dust deposit occurs in the superheater where its removal` is most readily eii'ect-ed.. The location. ofthe superheater immediately in front of the first pass of the boiler proper, insures the desired amount of: superheat with the minimum i amount of su erlieater surface and the'cooling ofthe heating, gases due tol their passage through the superheater K lis especially important in the construction illustrated, be- Y cause the. horizontal circulating tubes I5 are not normally filledwith waterbut normally contain both steam and water, and hence are more apt. to? be injured by overheating than are the water tilled tubes of theboiler., `With the described arrangement ythe superheater foi-msA a,v protecting gasV cooling mantle -or screen for thel circulating tubes I5.. Since n the flow of the heating gases throughthe irst passofi the` boiler is downward, gravity assistsin. carrying thedustfin the heating gases entering the: boiler proper', through-fthe inter-tube space ol? thel lirstpass o-iithe boiler yto the top of the dust pocket F4 into Which thi-sdust largely` settles because of the reduced velocity of heating gas new consequent urpon its reduction in temperature and boiler.,

volume as it travels through the first pass` and the reversal in direction of gas flow asjllt-where =it does-noti in terfere-with -theoperation-oil the boiler and with which provisions for removing the dust may readily be associated: v

The initial introduction of the heating gases into the boiler at the top facilitates a proper water circulation through the; water tubes andfheaderswhichis a mat-terespecially important because of.: the relatively vgreat number ofatube rows and verticaldepthV o fgthe intertube space :whichnisI desirably employed Y in awaste vheat boiler;l lVith-,thetype of boiler illustrated the major portion of; the .'heatabsorbed by. the boiler is.- absorbed in the upper portionof.theboiler,.indeedmorethanfhalfiof the totali amount ofi lieat taken up.Y by the; boiler will'ordinarily be; absorbed; in the p0rtions of the tubesI inthe-first pass oftthe In consequence` the. circulation. of steam and Waterin the'boiler, proper ismuch more rapid. in the-upper bank. of tubes If, the.

headers l? connected; thereto and connections from thoseflieadersto thefsteam dnumfl 4-than inthe lower portion ot the boiler; With, the most rapidy boiler circulation thus localized in the upper portion of the boiler, thelminie mum rictional, impedance to.' the required circulationri'ssecured'. In. the typeot boiler illustrated, the circulation in theY lower bank of tubes I will beto a considerableyextent, a local' circulation upward through theiloweri most tubes Iinto the corresponding upper lill) headerP, and theneebaclr throughthefuppery most tubes I into the lower header'f l?V to whichz the tubes I are l connected,I and' the .flow through the nipples I3 may becommensuratfe with the rate at which water isactua-lly evaporated in the bank of tubesl.A

llln'le in accordance. with. the, provisions; of

the statues I have illustrated and describedV the best embodiment of myinvention1 now' i "f known tov me it will be apparentto those skilled inthe artthat changes may be'made in the forni or they apparatus.disclosed.y without departing from the spirit of my invention as set forth in the appended claims, andthat in some. cases certainfeatu-res of my invention may sometimes be used to advantage without a. corresponding use. oli other features.

Having now described my invention, what I claim' as new and desire to obtainby Letters Patent,` y

l. The combination in a Waste; heat boiler of the horizontalwater tube type transversely baliied to provide a plurality of transverse passes for the heating gases, of means providlll? ing an inlet forthe heating gases opening downward to the upper end of the transverse passadjacentoneendoftheboiler,andcommon means for collecting dust separating out of the heating gases in said pass and the pass immediately adjacent thereto.

2. The combination with a waste heat boiler having a bank of horizontally inclined water tubes, and a heating gas inlet at the top of said boiler, of a superheater comprising `horizontal tubes located in and extendingl above a bank of inclined water tubes, and havv ing a heating gas inlet at the top of the boiler and above said circulation tubes, of a superheater above said inlet and said circulation tubes, and means for passing the heating gases into the boiler through said superheater and downward past said circulation tubes.

5. A waste heat boiler comprising upper and lower banks of Water tubes slightlyinclined to the horizontal, separate headers for each bank of tubes, nipples` connecting the adjacent headers of the two banks, a steam and water drum, horizontal circulation tubes connecting said drum tothe upper header of the upper tube bank, and means for passing the boiler heating gases through the upper bank of tubes before bringing them into contact with the tubes in the lower bank whereby a relatively slow steam and water circulation is had in the lower bank of tubes and in said nipples.

6. A waste heat boiler of the horizontal Y water tube type transversely battled to provide three passes for the heating gases and provided with a heating gas inlet at the upper end of the pass adjacent one end of the boiler, a dust collecting pocket beneath the last mentioned pass and the adjacent pass, and a heating gas outlet communicating with the lower end of the remaining pass.

Signed at 1,11 Broadway, N. Y., in the county of New York and State of NewYork this twenty-eighth day of September, A. D. 1923. Y

JOHN E. BELL.

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