US3400559A - Steam generator having a minimum load firing system - Google Patents

Steam generator having a minimum load firing system Download PDF

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Publication number
US3400559A
US3400559A US560446A US56044666A US3400559A US 3400559 A US3400559 A US 3400559A US 560446 A US560446 A US 560446A US 56044666 A US56044666 A US 56044666A US 3400559 A US3400559 A US 3400559A
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Prior art keywords
minimum load
firing system
steam generator
combustion chamber
minimum
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Expired - Lifetime
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US560446A
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English (en)
Inventor
Litwinoff Richard
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Sulzer AG
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Sulzer AG
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C99/00—Subject-matter not provided for in other groups of this subclass
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G5/00—Controlling superheat temperature
    • F22G5/02—Applications of combustion-control devices, e.g. tangential-firing burners, tilting burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2700/00—Special arrangements for combustion apparatus using fluent fuel
    • F23C2700/06—Combustion apparatus using pulverized fuel
    • F23C2700/066—Other special arrangements

Definitions

  • the invention relates to a steam generator having a minimum load firing system. More particularly, the invention relates to a steam generator having a minimum load rng system for operation during low demand periods.
  • the invention incorporates a llame height varying means into a minimum load firing system of a steam generator having a main firing system located within acombustion chamber.
  • the llame height varying means functions such as to redirect the flame produced 'by a fixedly mounted minimum load firing system to achieve a different height relative to a heating surface in the combustion chamber of the steam generator or to move a minimum load firing system relative to a heating surface in the combustion chamber.
  • the invention avoids any damage to the pipes of the ice steam generator by overheating. Further, the invention enables the llame height to be varied continuously or intermittently during a minimum load period such as at night and consequently permits the heat provided by the minimum load firing system to be distributed as uniformly as possible over the heating surfaces in the combustion chamber during the entire period. Moreover, the invention assists restarting of the steam generator after minimum load operation so that the process can take place more rapidly. Finally, the invention makes it possible to improve the temperature regulation of the steam generator at minimum operating loads by varying the llame height of the minimum load firing system for the purpose of modifying the heat absorption of the superheater and/or of the intermediate superheater heating surfaces.
  • FIG. l illustrates a diagrammatic longitudinal section through a steam generator with a minimum load firing system permanently mounted in the center of the combustion chamber;
  • FIG. 2 illustrates a longitudinal section through the minimum load firing system to a scale larger than that of FIG. 1;
  • FIG. 3 graphically illustrates the firing system output in relation to a base of the steam generator load
  • FIG. 4 illustrates a diagrammatic longitudinal section through a steam generator embodied with a minimum load firing system moveably disposed in the center of the combustion chamber;
  • FIG. 5 illustrates a diagrammatic longitudinal section through a steam generator combustion chamber embodied with a minimum load firing system capable of swivelling
  • FIG. 6 illustrates in diagramamtic form a regulator system for the steam generator according to FIG. 5.
  • a steam generator includes a combustion chamber 1 of rectangular cross section lined with pipes 2 which represent an evaporator heating surface and provided with re wall heating surfaces 46 in the upper part through which high pressure steam or partially expanded steam ows so that the heating surfaces 46 act as superheaters or intermediate superheaters.
  • heating surfaces 14, 15, 16 and 17, which may act as further heating surfaces for superheaters, intermediate superheaters and economisers, are mounted in the flue 11 of the steam generator in a conventional manner.
  • the main ring system is Kcomposed of burners 3 which are disposed in the four corners of the combustion chamber 1.
  • a minimum load firing system 5 is lixedly mounted and located in the center of the combustion chamber 1 and is supplied with fuel, such as oil, through a pipeline 6 and air through a pipeline 7.
  • fuel such as oil
  • Each pipeline 6 and 7 is provided with valves 18 and 19 respectively to control the flow of fuel and air therethrough.
  • a pipe coil 4 through which a coolant flows surrounds the part of the minimum load firing system 5 which eX- tends into the combustion chamber.
  • the pipe coil 4 is provided with Water as the coolant which is obtained from the Working medium circuit of the steam generator through pipe coils connected in parallel with the economiser heating surface.
  • the coolant enters the pipe coil 4 through an inlet 8 and exits through a discharge 9 for circulation through the pipe coil.
  • the minimum load firing system 5 is supplied with flue gas from a flue gas return line 10 connected to the flue 11 which terminates in the ring system 5.
  • the flue gas is supplied to the minimum load liring system by means of a blower 12 disposed in the pipeline 10 and the quantity of flue gas is adjusted by means of a Valve 13.
  • a valve 33 in the minimum load tiring system distributes the returned ilue gas in the form of a curtain over the tire.
  • the minimum load firing system is designed with the upper end of the combustion air pipelines 7 in the form of a pipe shell surrounded by the cooling pipe coil 4.
  • the end section of the ue gas return line 10 is formed with a restriction and located within the pipe shell 7.
  • the restricted end of the ue gas return line 10V is joined to the end of the pipe shell 7 through a coneshaped shell in which four uniformly distributed burners 22 are mounted circumferentially.
  • Each burner 22 is surrounded by concentric air diffusers 23 which may be adjustable.
  • the fuel supply line 6 extends into the ⁇ annular chamber between the pipe shell 7 and the flue gas line 10 and terminates in a ring main 25 from which a supply line 24 is branched off to each burner 22.
  • the upper restricted end of the flue gas line 10 houses a mushroom valve 33 having a stem 20 which is guided in two bearings 31 and 32 for closing the gas line 10.
  • the bearings 31, 32 are retained by four radial walls 30 which are secured to the pipeline 10 at a position in front of the restriction thereof.
  • a spring 34 is provided between the bearing 32 and the free end of the valve stem 20 to urge the mushroom valve 33 towards the pipeline 10.
  • Radial pipes 36 which terminate in a ring duct 35 extending around the internal circumference of the pipe shell 7 branch off from the ue gas line 10 approximately at half the height of the pipe shell 7 which projects into the combustion chamber. In the zone of the ring duct 35, the pipe shell 7 is provided with holes 37 through which the flue gas can escape and then flow upwards past the pipe coil 4.
  • the height of this flame will vary, depending on the position of the mushroom valve 33, so that the flue gas curtain which spreads over the flame alters its position so that the streaks of hot gas which are simultaneously emitted by the minimum load tiring system 5 are prevented from excessively heating individual tire walls or parts thereof.
  • the spring 34 urging the mushroom valve 33 towards the pipeline 10 ensures an adequate minimum exit velocity of the flue gas even if only a very small amount of flue gas is returned.
  • a temperature measuring point 95 is provided, for example, on one of the fire wall heating surfaces 46.
  • a steam generator provided with front burners 26 which function as the main firing system and designedyfor a high sub-critical pressure has a relatively .small evaporator heating surface.
  • This evaporator heating surface is formed bypipes 40 and 41 which line a combustion chamber 45 and terminate in a liquid separator 42.
  • the steam to be superheated reaches a pipeline wall which lines the upper part of the combustion chamber 45 as well as a pipeline wall 43 which covers the rear wall of the combustion chamber.
  • Fire wall heating surfaces 46 which function as heating surfaces for the intermediate superheater are provided in the upper part of the combustion chamber 45.
  • a minimum load ring system 21 which is vertically adjustable with the aid of telescoping pipes and which can also be completely withdrawn from the combustion chamber during operation of the main firing system is provided in the center of the combustion chamber cross section.
  • a fuel supply line in the form of a flexible hose 47 supplies fuel to the minimum load firing system 21 while combustion air ows upwards in the direction indicated by the arrows 48 within the telescoping pipes.
  • the amount of fuel and the amount of air are adjustable as above.
  • the minimum load firing system is not located within the combustion chamber during operation of the main tiring system, it is not necessary to provide protective devices such as the coolant pipe coils 4 of the above examples in accordance with FIGS. 1 and 2. Further, the minimum load tiring system 21 is ignited only after the lower row of the burners 26 of the main firing system is shut down.
  • a main firing system of a modied form of steam generator consists of a double U firing system in which burners 49 are disposed on so-callled banks above a combustion chamber 38.
  • the flames of the burners 49 are initially directed downwardly and then reversed to meet in the center of the combustion chamber 38.
  • the combustion chamber 38 is lined in a manner similar to that shown in FIG. 1 and the fire wall heating surfaces are positioned in the upper part of the combustion chamber.
  • the minimum load tiring system 39 is supported by an arm 80 which is located on one side of the combustion chamber 38 for swivelling around a horizontal axis 81.
  • the vertical position of the flame of the minimum load firing system 39 can thus be varied by appropriate adjustment of the swivelable arm 80.
  • the minimum load firing system 39 is shut down and the arm is swung into a chamber 82 which is located outside the combustion chamber for housing therein.
  • the arm 80 when positioned in the chamber 82 is therefore adequately protected from the main ring system.
  • the arm 80 is moved into the combustion chamber 38 and the minimum load firing system 39 is ignited. Thereafter, the arm is moved further into the combustion chamber depending on the desired llame height.
  • the steam generator of FIG. 5 is provided with an evaporator heating surface 50, an interconnected superheater heating surface 52 and a liquid separator 51 mounted in the linebetween the heating surfaces 50 and 52.
  • Superheated high pressure steam passes through a line 60 to a load which is not shown.
  • the end of the superheater 52 has a temperature measuring element 83 connected thereto which, by acting through a regulator 84, adjusts a valve 85 which is provided in a feed water line 86 connected on the inlet side of the evaporator heating surface 50.
  • the feed water line 86 terminates at 62 in the superheater 52 and the amount of water fed into the system is adjusted by means of the regulator 84 and the valve S5 so that the eXit temperature of the steam is maintained at a desired value.
  • Feed water is also supplied to the evaporator heating surface 50 by means of a feed pump 53 which is regulated by a regulator 77 which in turn is connected to a diaphragm 55 provided to measure the feed water flow rate.
  • the amount of fuel to be supplied to the burners 49 is adjusted with the aid of a valve 56 which is controlled by a regulator 87 connected to a diaphragm 88 which measures the fuel flow rate.
  • the amount of fuel to be supplied to the minimum load firing system 39 is adjusted by a valve 57 which, in the same way as the valve 56, is controlled by a regulator 89 connected to a diaphragm 90 which measures the fuel flow rate.
  • a pressure sensing element 63 which acts through a regulator 64 on to a load transmitter 65 is connected to the steam line 60.
  • the load transmitter 65 is connected by means of signal lines 66 and 6'7 to the fuel How rate regulator 87 of the main firing system and the fuel flow rate regulator 89 of the minimum load firing system to provide the regulators 87 and 89 with set-value signals.
  • the load transmitter 65 is connected by a set-value signal line 68 to a regulator 69 which is modulated by a temperature sensing element 91 provided upstream of the feed water inlet position 62 on the superheater 52 and which is connected by a signal line 79 to a servo-motor 70 which swivels or deflects the arm 80 of the minimum load firing system 39.
  • the arm 80 with the minimum load firing system is so deflected that it is raised when the steam temperature upstream of the feed water inlet position 62 is too low and vice versa.
  • the regulator 77 which controls the amount of feed water supplied receives a signal in a conventional manner from a regulator 76 via a line 92.
  • the signal received depends on the steam temperature of the section of the evaporator heating surface which is operated at superheat temperature.
  • the steam temperature is measured by a temperature sensing element 75 connected to the regulator 76; the regulator being provided with a set-value obtained from the -load transmitter 65 (not shown).
  • the temperature sensing element 75 is also connected with a comparator element 78 in which the temperature signal is compared with a limiting value provided through a line 93.
  • the comparator element 78 is connected to the signal line 79 to provide an overriding signal for the servomotor 70 if the steam temperature in that section of the evaporator heating surface which is operated at superheat should risel above the limiting value.
  • the overriding signal acts on the servomotor 70 to cause the ame of the minimum load firing system 39 to be displaced in a downward direction.
  • ame heights of the minimum load ring systems in the steam generators according to FIGS. 1 and 4 can also be regulated in relation to temperature.
  • said llame height varying means includes a ilue gas return line means for supplying flue gas to said minimum load tiring system, and an element mounted in said minimum load ring system in the path of flow of the supplied flue gas for distributing the supplied flue gas over said llame.
  • said means for producing a flame includes a plurality of circumferentially disposed burners
  • said ame height varying means includes a pipe disposed centrally of said burners for supplying flue gas to said minimum load firing system and a mushroom valve slidably mounted in said pipe in the path of ow of the supplied ue gas for distributing the supplied llue gas over said burners.
  • said means for varying the llame height includes a vertically ⁇ adjustable means supporting said minimum load firing system centrally of said combustion chamber for moving said minimum load ring system with respect to the interior of said combustion chamber.
  • said means for varying flame height includes a regulating device responsive to a temperature measured in a zone of the end of said combustion chamber to vary said flame height.
  • said minimum load firing system including means for producing a llame t0 operate the steam generator during shut down of the main firing system; means for varying the flame height of said minimum load firing system, said means for varying the llame height including la swivelly mounted arm supporting said minimum lload firing system for swivelling about a horizontal axis, said varm being mounted to a side of said combustion chamber.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Furnace Details (AREA)
US560446A 1965-07-01 1966-06-27 Steam generator having a minimum load firing system Expired - Lifetime US3400559A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH924065A CH441596A (de) 1965-07-01 1965-07-01 Dampferzeuger mit Kleinstlastfeuerung

Publications (1)

Publication Number Publication Date
US3400559A true US3400559A (en) 1968-09-10

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US560446A Expired - Lifetime US3400559A (en) 1965-07-01 1966-06-27 Steam generator having a minimum load firing system

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US (1) US3400559A (xx)
BE (1) BE683180A (xx)
CH (1) CH441596A (xx)
DE (1) DE1301428B (xx)
ES (1) ES328555A1 (xx)
GB (1) GB1090379A (xx)
NL (1) NL6512135A (xx)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2872886A1 (fr) * 2004-07-09 2006-01-13 Total Sa Procede et dispositif de generation de vapeur d'eau adapte a l'oxy-combustion

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000042354A1 (en) * 1999-01-13 2000-07-20 Abb Alstom Power Inc. Startup technique using multimode operation in a kalina cycle power generation system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2100190A (en) * 1937-03-02 1937-11-23 Comb Eng Co Inc Method of controlling superheat temperature
US2367193A (en) * 1941-11-04 1945-01-16 Foster Wheeler Corp Vapor generator
US2851018A (en) * 1953-04-30 1958-09-09 Babcock & Wilcox Co Steam generating unit with corner fired furnace and gas recirculation
US3003479A (en) * 1952-10-11 1961-10-10 Duerrwerke Ag Steam and air boiler with heating surface of smallest load
US3160146A (en) * 1962-03-19 1964-12-08 Riley Stoker Corp Furnace

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE521183A (xx) *

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2100190A (en) * 1937-03-02 1937-11-23 Comb Eng Co Inc Method of controlling superheat temperature
US2367193A (en) * 1941-11-04 1945-01-16 Foster Wheeler Corp Vapor generator
US3003479A (en) * 1952-10-11 1961-10-10 Duerrwerke Ag Steam and air boiler with heating surface of smallest load
US2851018A (en) * 1953-04-30 1958-09-09 Babcock & Wilcox Co Steam generating unit with corner fired furnace and gas recirculation
US3160146A (en) * 1962-03-19 1964-12-08 Riley Stoker Corp Furnace

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2872886A1 (fr) * 2004-07-09 2006-01-13 Total Sa Procede et dispositif de generation de vapeur d'eau adapte a l'oxy-combustion
WO2006016042A1 (fr) * 2004-07-09 2006-02-16 Total France Procede et dispositif de generation de vapeur d'eau adapte a l'oxy-combustion
US20070227145A1 (en) * 2004-07-09 2007-10-04 Total France Method and Device for Generating Steam Suited to Oxycombustion

Also Published As

Publication number Publication date
CH441596A (de) 1967-08-15
GB1090379A (en) 1967-11-08
BE683180A (xx) 1966-12-27
DE1301428B (de) 1969-08-21
NL6512135A (xx) 1967-01-02
ES328555A1 (es) 1967-04-01

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