US2397523A

US2397523A - Steam generator

Info

Publication number: US2397523A
Application number: US449732A
Authority: US
Inventors: Erwin G Bailey
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1942-07-04
Filing date: 1942-07-04
Publication date: 1946-04-02
Anticipated expiration: 1963-04-02

Description

-File July 4.

1942 3 Sheets-Sheet l BY- ,n/[n /ai/eg I ATIOQNEY April 2, 1946.

poooo ooooo E. G. BAILEY 2,397,523 S'IEAM GENERATOR Filed July 4, 1942 3 Sheets-Sheet 2 Ervin Gf Bailey A1 TUZNEY INVENTOR.

E. G. BAILEY STEAM GENERATOR gled July 4, 1942 Aprilrz, 1946.

3 Sheets-Sheet 3 7. 6 2 4 //r f ,w .I if v7.

0 .2 w fw M o d o U u o0 o o o o o o o O ol o NIV o o o o o ,o E l ATTORNEY Patented Apr. 2, 1946 STEAM GENERATOR d' Ervin G. Bailey, Easton, l'a.,I assigner to The Babcock & Wilcox Company, Jersey City, N. J.,

a corporation of New Jersey 'Application July 4, 1942, seria1N0.449,732

4 claims. (o1.l 12g-33m My invention relates to improvements in high pressure steam generators of the natural circulation type. These improvements insure effective circulation through iluid cooled tubes located in high temperature furnace zones, while utilizing the same fluid streams to further cool the furnace gases by means of convection heat transfer.

My invention is particularly applicable to high capacity units which operate at pressures approaching thecritical pressure of steam, where the density differential between water and steam I causing natural circulation) is reduced.

My invention is of particular advantage inits i application to high pressure steam generating units having a plurality of furnace stages, with;

certain of the highly heated steam generating tubes cooling the walls of the primary stage.

I have found that in the interest of assured and adequate flow of water through the highly heated roof tubes of the primary furnace and the highly heated partition tubes between the primaryfurnace and the secondary furnace of a two-stage furnace boiler unit, it is of particular advantage to provide for the fluid flow from these tubes to continue upwardly through a bank of inclined" steam generator tubes extending across thepath of gas ow from the secondary furnace.A

In order to insure the most eifectiveuse of the available water head to cause natural circulation through the distinct liquid flow paths, I utilize-` an outside unheated downcomer, and limit the use of junction headers which would retard circulation. 1 v r In compliance withthe law relating to patents,

and particularly Section 4888 R. S., the invention` Figs. 4 and 5 are vertical sections through simi-A lar steam generators illustrating dili'erent modifications.

Figs. G, 7, and 8 are vertical sections illustrating the tube arrangements in the ysteeply inclined convection tube banks of Figs. 1,4, and 5, re-

spectively, taken on the correspondingly numbered section lines of thoseligures Fig. 1 of the vdrawingsshows a steam generator including aV rst furnace chamber I fired by one or more fuel burners I2. The furnace gases pass v s from the lower part of the chamber I0 into the lower part of a second furnace chamber I4, steam being lgenerated `in both .furnace chambers by wall tubes dening boundary surfaces of the chambers. .l A

The furnace gases pass from the upper part of the furnaceechamber I4 over and between the steam generating Itubes of a steeply inclined convection tube bank I6, and beyond this bank of tubes the tubular elements of convection superheater sections |30 and |32 are heated by the gases. The superheater may beA limited to one of two parallel gas passes, and the control of supeheat may then be effected luy-regulation of the gas flow th'rough these passes. In that case one of the passes may be considered as a superheater bypass, and a part of the economizer surface maybe located in the bypass.

Y The first furnace chamber I0 is separated from the chamber |4 bya partition wall 32 including

steamfgenerating tubes

34 and 36, at least some of which aITorddirect communication between the steam and water drum 26 and the lower drum 4D. Near th'e lower parts of the furnace chambers the

wall tubes

34 and 36 are separated as indicated in the drawings to provide a gas outlet for the Vcombustion chamber or rst furnace chamber I0..

The illustrative lsteam generator also includes anr intermediate drum or header |42 having directy connection with the bank of steam generating tubes I6. Steam and water pass from the drum or header |42 to the steam and water drum 26 through the Ycirculators 44 and 46. The roof tube sections 50, wall tube sections 52, and floor tube sections 54 form continuous conduits extendingfrom the lower drum 40 to ay position beyond the furnace chamber I0.

It will be understood that there are rows of closely spaced tubes along thev various furnace boundary surfaces such as the floor, front wall, and roof of the chamber I0. Beyond this furnace chamber,` some of the roof tubes 50 are bent so as to extend through spaces between some of the tubes 34, such tubes being bent to the right to form the tube ysections 5W of the bank I6 (see Figs; 2 and 3). Others of the tubes 50 are bent so as to pass between successive tubes 34 at higher elevations to form the upper tube sections 50 of the bank I6. Space for the tube sections 50 and I use. l The Fig. l arrangement involves-two superheater Vsections |30-I32.

50 is provided by bending alternate tubes 34 out of their wall forming alignment so as to form the The lower tube secinclined tube sections 34'. tions 36', 36", and 36" of the bank IB are formed by bending other tubes 36 in the manner indicated in Figs. V2 and 3.

The lower part 60 of the rear wall ofthe furnace chamber |4'is inclined downwardly toward the floor of the combustion chamber I0. This wall and the upright wall 62 above are cooled by wall tubes 64 directly connecting the waterspacek system of the generator by the circulator 68, the headers l Vand 'I2 and the water connections 14.

In Fig. 5, the tubes I6 cooling walls '60 and 62 are directly connected to the drum 40 at their lower ends and to the drum 42 at their upper ends.

The latter drum is in direct communication with the steam and water drum 26 through the

circulators

44 and 46 as previously described.

tions is, as indicated by the reference characters applied thereto, much the same as that shown in Fig. 1 and above described with reference thereto.

This application is a continuation-impart of.

my earlier application 328,279 led on April 6, 1940 and allowed on November 21, 1941 (now Patent 2,293,040, August 18, 1942). Y

What is claimed is:

1. In a stream generator, an upper transverse horizontally extending steam and water drum,

The Fig. 5 modification additionally involves t inlet headers 80 and 82 for the bank of tubes I6.

The tubes 84-86 of the rst three rows are connected at their lower end to the header 80 while the

tubes

88 and 90 of the last two rows extend from the header 82 along the gas pass wall 92 to the drum 26.

Water flows from the header or drum to the iioor tubes 94 to the headerSB, and then i through the wall tube sections 9B, and roof tube sections |00 to the header 80. The headerv 82 is supplied with water by a connection |02 extending from the large diameter outside downcomer |04 directly connecting the water space of the drum 2'6 and drum 40.

' Steamjfrom the Fig. 5 steam and watermdrum passes through the circulators |10 to a superl heater inlet header H2 and thence through the tubes of a convection superheater H4 extendj ing across the gas path and connected to the superheater outlet header Iii. From this header the steam may pass to a desuperheater` and thence to the inlet header |20 of the second stage Vsuperheater |22. From the outlet header |24 of this superheater the steam passes to a point of However, in this case the two superheater sections are in series as to I steam ow through the header |34. To maintaina constant superheat at the outlet header |36, there may be a gas bypass control.

VThe Fig. 4 embodiment, shows two lower headers |40 and |42 for the bank Of tubes I6, the

` header |40 is supplied withwater through its connectionfwith some of vthe tubes defining the wall 32.

|54 to which the roof tubes for the combustion Such a connection is `illustrated at |52. Below the header |40 is a supplementary header chamber I0 are directly connected as indicated at I I56 and-|58.

Fig. 4 indicates an economizer 22 having tubular` elements disposed across a downilow of gases beyond the superheater i8 and connected-to the outlet header 24. The latter is Iconnected to the drum 26 bythe tubes 28 `and 30.

The general arrangement of first and second furnace chambers, fuel burners, and convection section, of each of the Fig. 4 and Fig. 5 modificasuperheater, a transversely extending a lower Water drum, downflow water conduits formed by direct connections between the water space of the upper drumand the lower drum, a fuel fired furnace positioned intermediate the upper druml and the lower drum, a horizontally extending multiple loop superheater arranged in an upwardly extending gas passage positioned below said steam and Water drum and leading from said furnace, a steam generating screen tube bank including a plurality of spaced inclined steamgenerating tube sections extending across said gas passage at a position below said water chamber connected to the upper ends of said steam generating tube sections andto the steam and water drum, said furnace having a part below said superheater with aroof portion extending outwardly from a position below the lower ends of the steam generating tube sections, roof cooling tube sections for said roof portion, means including upwardly extending tubular sections connecting the upper'ends of roof tube sections to the lower ends of the steam generating tubes for continuous upward fluid flow from the roof tube sections to and through the steam generating tube sections, and means connecting the lower ends of said roof cooling tubes to the lower'drum whereby the roof tubes and screen tubes are connected into the drum circulation.

2. In a steam generator, a steam and waterV drum disposed towardrthe top of the generator,

means forming a water drum disposed at the lower part of the generator, downcomer means connecting said drum and chamber, a primary furnace chamber in whichcombustion takes-place,

a secondary furnace chamber receiving furnace gases from the primary chamber, an intermediate Y drum or header exteriorly ofthe second chamber, and tubes disposed along a wall between said abank of steeply inclined steam generating tubesV extending across the path of furnace gases at the upper part ofthe second furnace chamber and at a position above the combustion chamber; transverse headers or drums disposed on opposite sides of the second furnace chamber and having the tubes of said bank lconnected thereto; a convection section including a superheater disposed above said bank of tubes; a steam and water drum above said convection section; a water drum below said furnace chambers; means connecting the Ywater drum and the steam and water drum; said means including wall cooling tubes disposed at opposite sides of the said furnace chamber with some of said tubes dening a partition wall separating the combustion chamber from the second furnace chamber; some of the tubes of said bank extending between spaced wall tubes for the second furnace chamber; and means whereby wall cooling tubes for the combustion chamber discharge into the lower header or drum for said bank of tubes.

4. In a steam generator, an upper steam and water drum, a lower water drum, downcomers directly connecting the water space of the upper drum with the lower drum, a fuel iired furnace positioned at a level intermediate the upper drum and the lower drum, means forming an upwardly extending gas passage positioned below said steam and water drum and leading from said furnace, a superheater including tubes in a multiple loop arrangement and extending horizontally across said gas passage, a superheater screen including a bank of spaced and inclined ste-am generating tubes extending across said gas passage at a position below said superheater, a transversely extending water chamber connected to the upper ends of the screen tubes and to the steam and water drum, said furnace having a portion below said superheater with a roof extending outwardly from a position below the lower ends of the tubes of the bank, water cooling tubes for said roof portion having their upper ends connected to the lower ends of the tubes of the bank for continued upward flow through the roof tubes and the steam generating tubes, and means connecting the lower ends of the roof tubes tothe lower drum whereby the roof tubes and screen tubes are connected into the drum circulation.

ERVIN G. BAILEY.