US3307523A - Steam generator organization - Google Patents

Steam generator organization Download PDF

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Publication number
US3307523A
US3307523A US487850A US48785065A US3307523A US 3307523 A US3307523 A US 3307523A US 487850 A US487850 A US 487850A US 48785065 A US48785065 A US 48785065A US 3307523 A US3307523 A US 3307523A
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US
United States
Prior art keywords
tubes
platens
furnace
furnance
steam heating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US487850A
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English (en)
Inventor
Palchik David
Ronald B Knust
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Combustion Engineering Inc
Original Assignee
Combustion Engineering Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Combustion Engineering Inc filed Critical Combustion Engineering Inc
Priority to US487850A priority Critical patent/US3307523A/en
Priority to GB37816/66A priority patent/GB1143478A/en
Priority to BE686680D priority patent/BE686680A/xx
Priority to NL6612743A priority patent/NL6612743A/xx
Priority to DE19661551001 priority patent/DE1551001A1/de
Priority to ES0331086A priority patent/ES331086A1/es
Application granted granted Critical
Publication of US3307523A publication Critical patent/US3307523A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B29/00—Steam boilers of forced-flow type
    • F22B29/06—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B29/00—Steam boilers of forced-flow type
    • F22B29/06—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes
    • F22B29/061—Construction of tube walls

Definitions

  • This invention relates to steam generators, and in particular to an apparatus for supporting and protecting steam heating surface from excessive heat during low load operation of the steam generator.
  • a plurality of platens are located at the furnace outlet. These platens, along with the furnace wall tubing, have high flow rates passing through them by recirculating fluid through these sections. These portions of the steam generator which are in the general area of the furnace and therefore subject to the relatively high radiant heat energy at low loads are therefore adequately protected.
  • the platens are located so as to effectively shield other sections of the steam generator which have lower flows from a major portion of the direct furnace radiation.
  • These platens and horizontal assemblies located above them are supported by tubes, some of which are at the inlet temperature of the platen and some of which are at the outlet temperature. The recirculation at low load maintains a low temperature difference across the platen and consequently a low temperature difference between the various support tubes.
  • the invention comprises an arrangement, construction, and combination of the elements of the inventive organization in such a manner as to attain the results desired, as hereinafter more particularly set forth in the following detailed description of an illustrative embodiment, said embodiment being shown by the accompanying drawings wherein:
  • FIG. 1 is a side elevation of the steam generator illustrating the general layout and showing in particular the location of the platens in respect to the furnace;
  • FIG. 2 is a detail of a portion of FIG. 1 which illustrates more clearly the arrangement of the platens and support tubes;
  • FIG. 3 is a sectional view taken through FIG. 2 selected to more clearly show the arrangement of the support tubes.
  • Fuel is passed through burners 2 for burning in the furnace 3.
  • Combustion gases formed by the burning of this fuel pass upwardly from the furnace through flue 4 traversing the heating surface and passing downwardly through flue 5. These gases pass to atmosphere through flue 6 which includes an air heater (not shown).
  • feedwater is supplied to the vapor generator through the economizer inlet header 10 at a temperature of 500 F.
  • This water is passed through the economizer 11 where it is heated to a temperature of 626 F. and then upwardly through the support tubes 12 to the economizer outlet header 13.
  • This water is then conveyed through the mixing vessel 14 and the downcomer 15 through recirculating pump 17 to the waterwall inlet headers 18.
  • Vertical tubes 19 line the four walls of the furnace and extend longitudinally from the bottom of the furnace to the roof of the steam generator. Water is passed through these tubes from the inlet headers 13 to the outlet headers 20 and in so doing is heated to a temperature of 761 F.
  • the water is conveyed from these outlet headers through pipe 22 to the rear pass headers 24 and then upwardly through tubes lining three walls of the rear gas pass to the rear pass outlet header 25.
  • the heat absorption in these walls is only nominal and, accordingly, the fluid is heated to a temperature of 765 F.
  • the fluid is conveyed through pipe 27 to the platen inlet header 28 wherein the majority of the flow passes through the platens 29 to the outlet platen header 30. In so doing the fluid is heated to a temperature of 836 F. The fluid leaving the platen 29 then passes upwardly through the support tubes 32 to header 33.
  • Fluid is conveyed from the header 33 through a boiler throttle valve 37 and thence to the low temperature steam superheating section 38.
  • the steam is then passed through the high temperature steam superheating sections 39 to the outlet header 40 form which point the steam is conveyed to a turbine (not shown).
  • Recirculating line 48 carries no fiow at this time with stop check valve 49 being closed.
  • the interrelation between this recirculating line and the recirculating pump 17 along with the characteristics produced by this design are discussed in U.S. Patent No. 3,135,252 issued to Willburt W. Schroedter.
  • the recirculating line 48 is active conveying a portion of the how passing through outlet header 33 back to mixing vessel 14 where this flow is mixed with the through-flow passing through the economizer and economizer outlet header 13.
  • This mixed flow passes through the downcomer 15 and is effective to increase the flow through the furnace wall tubes 19, the rear pass wall tubes and the platens 29 substantially above that flow passing through the superheater sections 39 and the reheater sections 46.
  • the arrangement of the support tubes 32 and 34 is more clearly seen with reference to FIGS. 2 and 3.
  • Support tubes 34 leave the inlet header 28 and pass parallel to the platens 29 adjacent the lower edge. At a preselected support location two of these tubes are bent outwardly and pass vertically with one on each side of the platen units.
  • the same support tubes continue upwardly with one passing on each side of the reheater 46 and superheater 39.
  • the assemblies which are in the same plane as the platens, are supported from the support tubes at those points where they intersect.
  • the support tubes then continue upwardly to the roof 52 where they are supported by the roof seals 53, then passing into the outlet header 33.
  • the platens 29 are located on 2 ft. 2% inch centers. This wide spacing being required to avoid any possibility of slag bridging between platen assemblies when burning fuels with slagging characteristics.
  • the reheater assemblies 46 and superheater assemblies 39 are on 8% inch centers in order to improve the convective heat transfer rate and obtain more surface in a given volume. Accordingly, there are intermediate assemblies which are not in line with the panels which must be supported. This is acomplished by using the support tube 32. which receive their flow from the platen outlet header. These tubes pass parallel to the platens adjacent the upper edge thereof to a preselected location where they turn upwardly.
  • these tubes are bent outwardly from the plane of the platen so that one tube passes up on each side of the assemblies.
  • the assemblies are supported from these tubes as they were from the support tubes 34 and these support tubes are, in turn, supported by the roof seal 53.
  • the platen 29 passes through the furnace wall tubing 19 in the front wall. As the unit heats up, there is an expansion between the roof of the gas pass and the location where the platens pass through the wall, which is a function of the temperature of the tubes 19 in the walls of the gas pass.
  • the support tubes 32 and 3% also expand due to the temperature at which they operate. While a reasonable difference in expansion can be absorbed by allowing sufficient length for the tubes to fiex, if there is excessive differential expansion between any of these three portions, undue stresses or strains would occur during operation of the unit.
  • the average metal temperature of the upper wall tubes 19 is 800 F.
  • the average metal temperature of the support tubes 32 is 860 F. while the average metal temperature of the support tubes 34 is 855 F.
  • the temperature of the various support tubes is extremely close, which is important since it is difiicult to provide suflicient horizontal run to absorb differential expansion between support tubes.
  • the differential between the support tubes and upper wall tubes does not exceed 60 F. and the differential expansion for this can be easily absorbed in the extended horizontal run available.
  • the platen 29 absorbs much of its heat by radiation, this platen has what is called a rising temperature characteristic. This means that as load is decreased the heat absorption of the platen relative to the output of the steam generator increases. Accordingly, the temperature difference across the platen at low loads increases and tends to be excessive. This creates stresses, not only due to differential expansion between the upper walls 19 and the support tubes 32 and 34, but also between the inlet and outlet passes of the platen 29. Recirculation at low loads avoids the critical temperature difference at these difiicult operating conditions.
  • the platen inherently suffers unbalance in heat absorption between parallel tubes. When the temperature difference is high, this unbalance results in very high temperatures in some of the tubes. Recirculation also avoids these high unbalanced temperatures.
  • the recirculating pump floats on the through-flow circuit as described in ⁇ 1.8. Patent 3,135,252. Accordingly, the recirculation is increased with decreasing load, thereby countering the rising heat absorption characteristic.
  • the platens so located are well protected with the excess flow and are operative to shield the reheater 46 from a high percentage of the furnace radiation which is relatively high as compared to the low flow through the reheater at reduced loads. During first periods of startup there is no flow at all through the reheater, and the shielding by the platens is of particular benefit.
  • a vapor generator of the once-through type having a furnace; means for burning fuel within said furance; means for conveyong combustion gases from said furnace; a through-flow circuit comprising a first portion including tubular surface lining the walls of said furnace; a second portion including a plurality of platens located at the outlet of said furnace and being positioned parallel to each other, a third portion including steam heat-ing surface located in said gas conveyong means; said first, second, and third portions arranged to convey fluid serially therethrough; low pressure steam heating surfaces located in said gas conveying means; each of said platens comprising a plurality of horizontal intermes-hed tubes and located intermediate said furnace and said low pressure steam heating surface so as to effectively shield said low steam heating surface from a large portion of the radiant heat emanating from said furnace; means for passing a substantially greater quantity of fluid through said first and second portions than through said third portion; said low pressure steam heating surface including a plurality of assemblies, each comprised of a plurality of tubes intermeshed with each other and in the same plane as corresponding panels
  • An apparatus as in claim 1 including also a plurality of assemblies of low pressure steam heating surface intermediate those assemblies of low pressure steam heating surface which are in the same planes as the platens; a plurality of intermediate support tubes for said intermediate assemblies receiving fluid egressing from the platens, comprising tubes passing parallel to the platens adjacent the upper edge thereof, each of said intermediate support tubes exending outwardly from the corresponding platen and thence upwardly, passing immediately adjacent to an intermediate assembly; means for supporting the weight of the intermediate assemblies from said intermediate support tubes; and means for supp-orting said intermediate support tubes at the support elevation.
  • An apparatus as in claim 2 wherein said means for passing a substantially greater quantity of fluid through said first and second portions than through said third portion comprises a recirculating system superimposed on said through-flow circuit and effective to recirculate fluid through said first and second portions in supplement to the through-flow.
  • a vapor generator of the oncethrough type having a furnace; means for burning fuel within said furnace; means for conveying combustion gases from said furnace; a through-flow circuit comprising a first portion including tubular surface lining the walls of said furnace; a second portion including a plurality of platens located at the outlet of said furnace and being positioned parallel to each other, a third portion including steam heating surface located in said gas conveying means; said first, second, and third portions arranged to convey fluid serially therethrough; each of said platens comprising a plurality of horizontal intermeshed tubes and located intermediate said furnace and said third portion; means for passing a substantially greater quantity of fluid through said first and second portions than through said third portion; said second section including a plurality of support tubes for the platens comprising tubes passing parallel to the platens adjacent the lower edge thereof, each of said tubes passing upwardly immediately adjacent the corresponding platen; means for supporting the weight of the platens from the adjacent support tubes; said first portion also including vertical tubular surface lining the walls of said gas conveying means and extending
  • the support tubes for the platens comprises pairs of tubes passing parallel to the platens adjacent the lower edge thereof, with said tubes dividing and passing upwardly with one tube on each side of the corresponding platen.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Fluidized-Bed Combustion And Resonant Combustion (AREA)
  • Gas Burners (AREA)
US487850A 1965-09-16 1965-09-16 Steam generator organization Expired - Lifetime US3307523A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US487850A US3307523A (en) 1965-09-16 1965-09-16 Steam generator organization
GB37816/66A GB1143478A (en) 1965-09-16 1966-08-23 A once-through vapor generator
BE686680D BE686680A (instruction) 1965-09-16 1966-09-09
NL6612743A NL6612743A (instruction) 1965-09-16 1966-09-09
DE19661551001 DE1551001A1 (de) 1965-09-16 1966-09-10 Durchlaufdampferzeuger
ES0331086A ES331086A1 (es) 1965-09-16 1966-09-10 Un generador de vapor de un solo paso.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US487850A US3307523A (en) 1965-09-16 1965-09-16 Steam generator organization

Publications (1)

Publication Number Publication Date
US3307523A true US3307523A (en) 1967-03-07

Family

ID=23937367

Family Applications (1)

Application Number Title Priority Date Filing Date
US487850A Expired - Lifetime US3307523A (en) 1965-09-16 1965-09-16 Steam generator organization

Country Status (6)

Country Link
US (1) US3307523A (instruction)
BE (1) BE686680A (instruction)
DE (1) DE1551001A1 (instruction)
ES (1) ES331086A1 (instruction)
GB (1) GB1143478A (instruction)
NL (1) NL6612743A (instruction)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3461846A (en) * 1966-07-11 1969-08-19 Combustion Eng Steam generators
US3754533A (en) * 1971-11-24 1973-08-28 Babcock & Wilcox Ltd Tube support system
US4063534A (en) * 1975-05-22 1977-12-20 Kraftwerk Union Aktiengesellschaft Coal-fired steam generator with heating surfaces above the firing or combustion chamber

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1942861A (en) * 1930-11-07 1934-01-09 Fried Krupp Germaniawerft Ag Producing high-pressure steam
US2091231A (en) * 1934-12-27 1937-08-24 Babcock & Wilcox Co Fluid heat exchange apparatus
US2416462A (en) * 1942-11-12 1947-02-25 Babcock & Wilcox Co Method of and apparatus for recovering heat and chemicals
US3185136A (en) * 1963-11-26 1965-05-25 Combustion Eng Steam generator organization

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1942861A (en) * 1930-11-07 1934-01-09 Fried Krupp Germaniawerft Ag Producing high-pressure steam
US2091231A (en) * 1934-12-27 1937-08-24 Babcock & Wilcox Co Fluid heat exchange apparatus
US2416462A (en) * 1942-11-12 1947-02-25 Babcock & Wilcox Co Method of and apparatus for recovering heat and chemicals
US3185136A (en) * 1963-11-26 1965-05-25 Combustion Eng Steam generator organization

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3461846A (en) * 1966-07-11 1969-08-19 Combustion Eng Steam generators
US3754533A (en) * 1971-11-24 1973-08-28 Babcock & Wilcox Ltd Tube support system
US4063534A (en) * 1975-05-22 1977-12-20 Kraftwerk Union Aktiengesellschaft Coal-fired steam generator with heating surfaces above the firing or combustion chamber

Also Published As

Publication number Publication date
NL6612743A (instruction) 1967-03-17
BE686680A (instruction) 1967-03-09
GB1143478A (en) 1969-02-19
ES331086A1 (es) 1967-11-16
DE1551001A1 (de) 1969-12-04

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