US3136301A

US3136301A - Tubulous vapor generating and superheating units

Info

Publication number: US3136301A
Application number: US180241A
Authority: US
Inventors: Kellet Gordon Mclagan
Original assignee: Babcock and Wilcox Ltd
Current assignee: Babcock International Ltd
Priority date: 1961-03-24
Filing date: 1962-03-16
Publication date: 1964-06-09
Anticipated expiration: 1981-06-09
Also published as: NL123634C; NL276010A

Description

June 9, 1964 G. MCLAGAN KELLx-:T

TUBULOUS VAPOR GENERATING AND SUPERHEATING UNITS 4 Sheets-Sheet 1 Filed March 16, 1962 /N VEN 70K Gordon Mc Lagan Kelle'r A TTOE/VEY June 9, 1964 G, MGLAGAN KELLET 3,136,301

TUBULOUS VAPOR GENERATING AND SUPERHEATING UNITS Filed March 16, 1962 4 Sheets-Sheet 2 1o 29 T V I June 9, 1964 G, MCLAGAN KELLET 3,136,301

TUBuLoUs VAPOR GENERATING AND SUPERHEATING UNITS F11-ed Maron 1e, 1962 4 sheets-sheet s June 9, 1954 G. MCLAGAN KELLET TUBULOUS VAPOR GENERATING AND SUPERHEATING UNITS 4 Sheets-Sheet 4 Filed March 16, 1962 FLg.

l X i l x x l K x RK x l l x l I xi United States Patent 3,136,301 TUBULOUS VAPOR GENERATING AND SUPERHEATING UNITS Y Gordon McLagan Kellet, London, England, assigner to Babcock & Wilcox, Limited, London, England, a company of Great Britain Filed Mar. 16, 1962, Ser. No. 180,241 Claims priority, application Great Britain Mar. 24, 1961 4 Claims. (Cl. 122-480) This invention relates to vapor generating and superheating units, an object being the provision of an improved superheater arrangement applicable to marine boilers.

Superheating means for a marine boiler have to meet various requirements among which is the necessity that the superheating means shall not involve any unnecessary use of space while it is very desirable to provide for ready renewal of low temperature superheater tubes,

A tubulous vapor generating and vapor heating unit according to the present invention includes a bank of tubes extending across a gas passage and forming two low ternperature superheater vapor passes in the first of which the tubes extend between an inlet header and a transfer header disposed atthe same side of the tube bank as the inlet header and in the second of which the tubes extend between the transfer header and an intermediate header dis posed at the side of the tube bank remote from the transfer header adjacent a high temperature superheater and serving as an inlet header to the high temperature superheater.

The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE l is an elevation of a marine boiler in section on the line I-I of FIGURE 2;

FIGURE 2 is a plan of the boiler in section on line Y II--II of FIGURE l;

VFIGURES

3 and 4 are plans of part of the boiler including the superheaters thereof in sections respectively on the lines III--III and IV-IV of FIGURE 1, and

FIGURE 5 shows schematically, in perspective fashion, the components of the superheaters to illustrate the relative positions which they bear to one another in the boiler,

' positioned. Two parallel

gas ilow paths

5 and 6, separated by a vertical division wall 7, lead the gases laterally from the furnace chamber below a horizontally arranged upper steam and water drum 8 and above a horizontally arranged water drum 9, the front gas ilow path 5 containing superheating surfaces which will be subsequently referred to, which surfaces are followed in the direction of gas ow by a bank 10 of steam generating tubes vertical over most of their lengths and extending between the upper drum 8 and the lower drum 9, and the rear gas ow

path containing banks

11, 12 and 13 in succession in the direction of gas ilow each of steam generating tubes extending between the upper drum 8 and the lower drum 9. i

Between the furnace chamber and the parallel gas paths is a screen 14 extending from front to rear of the furnace chamber, comprising two staggered rows of steam generating tubes extending between the upper drum 8 and a horizontally arranged header 15 having its axis below the axis of the lower drum 8 and connected by connectors 21 to the lower drum 9; The furnace Patented June 9, 1964 ylower end of said wall, which header is connected to the header 15 by front and rear connectors of which the rear connector 25 serves as'the lower header for steam generating tubes 26 cooling the rear wall of the furnace chamber and extending between the upper drum 8 and said connector 25. j

The -gases of the front'v gas ow path on leaving the steam generating'tube bank 10 and the gases of the rear gas ilow path on leaving the steam generating tube bank 13 enter

respective spaces

27 and 28 between theV said banks4 and a side wall 29 of the boiler. A plate wall 30, uncooled, extends the vertical division wall 7 and reaches to the side wall 24 and separates the

spaces

27 and 28, which communicate with the ships stack (not shown) through respective passages leading upwardly to the side of the upper drum 8 and containing respective economizer surfaces; the passage 31 leading upwardly from the front space 27 and containing economizer surfaces 32 is shown in FIGURE l. These passages contain respective dampers, the dampers in the passage 31 being denoted by the reference numeral 33.

The complete boiler is enclosed in a casing 34, spaced outwardly vfrom the various walls defining the furnace Vchamber and the gas flow paths. To the space 35 between the casing 34 and the said walls a ow of cooling air is supplied, which enters the furnace chamber 1 through the firing ports 3 as combustion air. The necessary downcomer pipes 36 between the water space of the upper steam andwater drum 8 and the water drum 9 are accommodated in said space 35.

The superheating surfaces referred to, located in the front gas flow pa-th 5 between the screen 14 and the steam generating tube bank 10, are arranged to form a high temperature superheater 41 rst contacted by the hot gases in the said gas flow path and a low temperature superheater 42 behind the high temperature superheater ,insaid gas flow path. The low temperature superheater 42 comprises an upper section 42a providing a first steam pass-and a lower section 42b providing a second steam pass. l

The upper low temperature superheat section 42a comprises horizontal straight tube limbs arranged in vertical vrows side by side. Each tube provides a plurality of tube limbs and extends in a horizontal plane; each tube is connected at its inlet end to an upright inlet header'43 which is located to the front of the gas flow path'5, vextends several times to and fro in sinuous fashion across the gas flow path 5 and is connected at its outlet end to an upright transfer header 44 also located to the front 0f the gas flow path 5. The inlet header 43 is disposed to the side of the low temperature superheater remote from the furnace chamber 1 and does not extend over the height of the lower low temperature superheater section 42b. The

transfer header 44 is also disposed to the side of the low temperature superheater remote from the furnace chamber 1 and extends over the whole height of the low temperature superheater, the upper part of the transfer header 44 receives the steam from the tubes of the upper low temperature superheater section 42a and the lower part thereof is arranged to pass the steam to the lower low temperature section 42b.

The lower low temperature superheater section 42b comprises horizontal straight tube limbs arranged in vertical rows side by side. Each tube provides a plurality of tube limbs and extends in a horizontal plane; each tube is connected at itsinlet en d to the lower part of the transfer header 44, extends several times to and fro in sinuousv fashion across the gas flow path 5 and is connected at its outlet end to an upright intermediate header 45 also located to the front of the gas flow path 5 and adjacent the high temperature superheater 41. The intermediate header 45 is disposed to the side of the low temperature superheater 42 nearer to the high ternperature superheater 41 and to the side `of that superheater remote from the furnace chamber 1.

Each tube of the lower low temperature superheater section 4212v comprises alpair of straight limbs 46'connected by a return bend 47 and a pair of straight limbs 48 connected by a return bend 49, the adjacent limbs of the two pairs being connected by a return bend 50; thus each tube is of approximately W shape. There are two tubes of the lower Y,section 42b in each horizontal tube plane. Each tube of the upper section 42a also comprises straight limbs 51 similar to the limbs 46 and straight limbs v52 similar to the limbs 48, connected in series by

return bends

53, 54 and 55 similar respectively to the

tube bends

47, 49 and 50 but for each tube of the upper section 42a an additional return bend 56, connecting together tube limbs 52 remote from the inlet and transfer headers, is provided so that the steam flows rst in a general direction towards the furnace chamber and then in the reverse sense; each tube of the upper section'42a includes all the tube limbs in the same horizontal plane and these comprise twice the number of limbs asa tube of the lower section.

The low temperature superheater 42 has the same vertical tube pitch and the same tube bore throughout. The height of the upper section 42a thereof is double the height of the lower section 42b thereof but by virtue of the described tube arrangements the number of tubes in each section is the same and therefore the mass ow rate through the tubes is the same throughout the low temperature superheater.

The high temperature superheater 41 comprises a lower section 41a providing a first steam pass and an upper section 41b providing a second steam pass and al1 the tubes thereof extend between the mentioned intermediate header which extends throughout the height of the high temperature superheater and a second transfer header 61 which also extends throughout the height of the high Vtemperature superheater and is disposed to the side of the said superheater nearer the furnace chamber.

The lower high temperature superheater section 41a comprises horizontal tube limbs arranged in verticalrows side by side. Each tube provides a plurality of tube limbs and extends in a horizontal plane. Each tube is connected at its inlet end Vto the lower part or connecting section of the intermediate header 45, extends several times tov and fro in sinuous fashion across the gas ow path 5 in a Ageneral direction towards the furnace chamber and is connected at its lower end to the lower part of the second transfer header 61. The upper high ternperature superheater section 41b comprises horizontal tube limbs arranged in vertical rows side by side. Each tube thereof provides a plurality of tube limbs and extends in a horizontal plane; each tube is connected at its inlet end to the upper part of the second transfer header 61, extends to and fro in sinuous fashion across the gas ow path in a general direction away from the furnace chamber andis connected at its outlet end to the upper part or outlet section of the intermediate header 45. Within the intermediate header 45 is a diaphragm 62 separating the lower part thereof from the upper part thereof, from which latter the superheated steam is taken to the desired point of use. Y

The high temperature superheater 41 has the same tube pitch and the same tube diameter throughout and the heights of the upper and lower sections 41b and '41a are the same. The vertical extent of the lower part of the intermediate header 45 is greater than the vertical extent of the lower section42b of the 10W temperature superheater and the diaphragm 62 in the intermediate header is substantially spaced above the points, indicated by 62, of entry into the said header of the'tubes of the low temperature superheater section 42h.

The low temperature superheater tubes are expanded i into the headers therefor, that is to say, into the inlet header 43, the transfer header 44 and the intermediate header 45. The high temperature superheater tubes are, however, weldedfthrough nipples to the headers therefor, that is to say, to the intermediate header 45 and the second transfer header 61.

Refractory 64 associated with upper and lower parts of tubes of the screen 44 ensure that gases in the front gas flow path 5 do not bypass the superheating surfaces.

The superheater tubes are supported by any suitable means, which may include, for the tube parts remote from the headers, supports 65 of known kind secured to a tube of the tube screen 14 and to three tubes 66 extending between the drums 8 and 9.

In the operation of the boiler, the steam generatedy in the various steam generating tubes when the furnace chamber 1 is fired is separated from water in the upper vdrum 8 and is led tothe low temperature superheater inlet header 43 whence it flows through the tubes of the lower temperature superheater upper section 42a to the upper part of thevtransfer header 44. In the transfer header the steam flows into the lower part thereof and thence through the tubes of the low temperature superheater lower section to the lowermost part of the intermeditae header 45. The steam lls the Whole of the lower part of the intermediate header V45 below the diaphragm 62 and flows thence through the tubes of the high temperature superheater lower section 41a to the lower part of the second transfer header 61. In the second transfer header the steam flows into the upper part thereof and thence through the tubes of the high temperature superheater upper part 41b to the upper part of the intermediate 'header 45. A high temperatureV of superheat is available,. since the high temperature superheater 41 is separated from the furnace chamber simply by the screen 44 of steam generating tubes. Superheat temperatures may be regulated by control through adjustment 'of the dampers of the distribution of the gas flow from the furnace-chamber between the

gas flow paths

5 and 6.

Y Since the lower section of the intermediate header 45 serves as the connection between the low temperature and the

high temperature superheaters

42 and 41, the arrangement avoids the use of one outlet header for the low temperature superheater and a Vseparate inlet header parallel thereto for the high tempertaure superheater, the connection between which has frequently consisted of a large diameter pipe which involves an undesirable degree of rigidity between the two headers unless a bulky expansion loop is included therein, and which moreover, is likely to enforce a high minimum spacing between the low temperature and the high temperature superheaters. As it is, the spacing between the two

superheaters

41 and 42 is no more than that required to afford the desired access space therebetween.

The space between the two superheaters is entered by a workman when necessary, when the boiler is cold, through an access opening 67 in the front wall of the front gas ilow path 5. Y

During a reft, tubes of the low temperature superheater or of the high temperature superheater may be replaced as necessary without disturbing the various headers, which are not in the way of forward withdrawal of failed superheater tubes, after they have been cut out, through the front wall of the gas flow path 5 and through the casing 34 when appropriate panels therein, not indicated, have been removed and which are similarly not in the way of the subsequent rearward insertion of fresh superheater tubes.

The disposition of the second transfer header 61 to the u side of the high temperature superheater nearer the furadvantage accrues owing to the disposition of the intermediate header 45 to the side of the higher temperature superheater remote from the furnace chamber.

The pipework connections to the inlet header 43 and from the outlet section of the intermediate header 45 are easily arranged since these two headers are not immediately adjacent one another.

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 form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

The claims are:

l. In a vapor generating superheating unit, Walls including vapor generating tubes forming a furnace, a gas pass leading from the furnace, a superheater disposed in and extending across said gas pass and comprising a first bank of looped tubes forming two low temperature superheater vapor passes situated one directly above the other, a second bank of looped tubes disposed upstream gas-fiow wise of said first bank of looped tubes and forming two high temperature superheater vapor passes situated one directly above the other, an inlet header disposed to the side of said first tube bank farthest from the furnace and connected for flow of fluid from the vapor generating tubes, a first transfer header disposed at the same side of the first tube bank as the inlet header, an intermediate header divided into two sections and disposed at the side of the first tube bank nearest to the furnace and adjacent to the side of said second tube bank farthest from the furnace, a second transfer header disposed to the side of said second tube bank nearest to the furnace, the tubes of one of the low temperature superheater vapor passes extending between and directly connected to the inlet header and the first transfer header, the tubes of the other low temperature superheater vapor pass extending between and directly connected to the first transfer header and one of the sections of the intermediate header, the tubes of one of the high temperature superheater vapor passes extending between and directly connected to said one section of the intermediate header and the second transfer header, and the tubes of the other high temperature superheater vapor pass extending between and directly connected to said second transfer header and the other section of said intermediate header.

2. In a vapor generating superheating unit, walls including vapor generating tubes forming a furnace, a gas pass leading from the furnace, a superheater disposed in and extending across the gas pass and comprising a first bank of horizontally extending looped tubes forming first and second low temperature superheater vapor passes, a second bank of horizontally extending looped tubes disposed upstream gas-flow wise of said rst bank of looped tubes and forming first and second high temperature superheater vapor passes, the tubes of the first low temperature vapor pass being situated directly above the tubes of the second low temperature vapor pass, the tubes of the first high temperature vapor pass being situated directly below the tubes of the second high temperature vapor pass, an upright inlet header disposed to the side of the first tube bank farthest from the furnace and connected for fiow of fluid from the vapor generating tubes, an upright first transfer header disposed at the same side of the first tube bank as the inlet header, an upright intermediate header divided into upper and lower sections and disposed at the side of the first tube bank nearest to the furnace and adjacent to the side of the second tube bank farthest from the furnace, an upright second transfer header disposed to the side of said second tube bank nearest to the furnace, the tubes of the first low temperature vapor pass extending between and directly connected to the inlet header and the first transfer header, the tubes of the second low temperature vapor pass extending between and directly connected to the first transfer header and the lower section of the intermediate header, the tubes of the first high temperature vapor pass extending between and directly connected to the lower section of the intermediate header and the second transfer header, and the tubes of the second high temperature Vapor pass extending between and directly connected to the second transfer header and the upper section of the intermediate header.

3. A unit as claimed in claim 1, wherein in the first bank of tubes forming the two low temperature superheater vapor passes the tube pitch and the tube bores and the number of rows of tube limbs transverse to the gas flow are the same throughout the tube bank while the numbers of tubes in the two passes are chosen to give equal or approximately equal mass flows of vapor throughout the tubes of the bank.

4. A unit as claimed in claim 1 wherein the tubes of the first low temperature vapor pass comprise one group of adjacent tubes and the tubes of the second low ternperature vapor pass comprise another group of adjacent tubes of the tube bank, the tubes of the first low temperature vapor pass occupying approximately two thirds of the distance between opposite boundaries of the gas pass and the tubes of the second low temperature vapor pass occupying the remainder of the distance.

References Cited in the file of this patent UNITED STATES PATENTS 2,939,435 Ressler June 7, 1960 FOREIGN PATENTS 58,455 Netherlands Nov. 15, 1946 291,507 Great Britain June l, 1928

Claims

1. IN A VAPOR GENERATING SUPERHEATING UNIT, WALLS INCLUDING VAPOR GENERATING TUBES FORMING A FURNACE, A GAS PASS LEADING FROM THE FURNACE, A SUPERHEATER DISPOSED IN AND EXTENDING ACROSS SAID GAS AND COMPRISING A FIRST BANK OF LOOPED TUBES FORMING TWO LOW TEMPERATURE SUPERHEATER VAPOR PASSES SITUATED ONE DIRECTLY ABOVE THE OTHER, A SECOND BANK OF LOOPED TUBES DISPOSED UPSTREAM GAS-FLOW WISE OF SAID FIRST BANK OF LOOPED TUBES AND FORMING TWO HIGH TEMPERATURE SUPERHEATER VAPOR PASSES SITUATED ONE DIRECTLY ABOVE THE OTHER, AN INLET HEADER DISPOSED TO THE SIDE OF SAID FIRST TUBE BANK FARTHEST FROM THE FURNACE AND CONNECTED FOR FLOW OF FLUID FROM THE VAPOR GENERATING TUBES, A FIRST TRANSFER HEADER DISPOSED AT THE SAME SIDE OF THE FIRST TUBE BANK AS THE INLET HEADER, AN INTERMEDIATE HEADER DIVIDED INTO TWO SECTIONS AND DISPOSED AT THE SIDE OF THE FIRST TUBE BANK NEAREST TO THE FURNACE AND ADJACENT TO THE SIDE OF SAID SECOND TUBE BANK FARTHEST FROM THE FURNACE, A SECOND TRANSFER HEADER DISPOSED TO THE SIDE OF SAID SECOND TUBE BANK NEAREST TO THE FURNACE, THE TUBES OF ONE OF THE LOW TEMPERATURE SUPERHEATER VAPOR PASSES EXTENDING BETWEEN AND DIRECTLY CONNECTED TO THE INLET HEADER AND THE FIRST TRANSFER HEADER, THE TUBES OF THE OTHER LOW TEMPERATURE SUPERHEATER VAPOR PASS EXTENDING BETWEEN AND DIRECTLY CONNECTED TO THE FIRST TRANSFER HEADER AND ONE OF THE SECTIONS OF THE INTERMEDIATE HEADER, THE TUBES OF ONE OF THE HIGH TEMPERATURE SUPERHEATER VAPOR PASSES EXTENDING BETWEEN AND DIRECTLY CONNECTED TO SAID ONE SECTION OF THE INTERMEDIATE HEADER AND THE SECOND TRANSFER HEADER, AND THE TUBES OF THE OTHER HIGH TEMPERATURE SUPERHEATER VAPOR PASS EXTENDING BETWEEN AND DIRECTLY CONNECTED TO SAID SECOND TRANSFER HEADER AND THE OTHER SECTION OF SAID INTERMEDIATE HEADER.