US3648667A - Apparatus and method for starting up a steam generator - Google Patents

Apparatus and method for starting up a steam generator Download PDF

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Publication number
US3648667A
US3648667A US71437A US3648667DA US3648667A US 3648667 A US3648667 A US 3648667A US 71437 A US71437 A US 71437A US 3648667D A US3648667D A US 3648667DA US 3648667 A US3648667 A US 3648667A
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Prior art keywords
flow
superheater
feed water
evaporator
line
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US71437A
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English (en)
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Richard Dolezal
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Sulzer AG
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Sulzer AG
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Publication date
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B35/00—Control systems for steam boilers
    • F22B35/06—Control systems for steam boilers for steam boilers of forced-flow type
    • F22B35/14—Control systems for steam boilers for steam boilers of forced-flow type during the starting-up periods, i.e. during the periods between the lighting of the furnaces and the attainment of the normal operating temperature of the steam boilers

Definitions

  • This invention relates to an apparatus and method for starting up a steam generator.
  • the invention provides a method and apparatus for starting up a steam generator in a manner to permit a rapid increase in the firing rate.
  • the method of the invention involves the steps of supplying a flow of feed water to the'inlet of a steam generator for flow first through the tube system of the steam generator and then through a bypass line, and supplying, from a time no later than when the fire in the combustion chamber of the steam generator is ignited, additional feed water to the superheater of the steam generator tube system while bypassing the evaporator of the steam generator tube system.
  • This additional feed water is fed at a rate of flow at least 30 percent larger than the rate of flow of the feed water supplied to the inlet of the system generator.
  • the method includes the subsequent step of suddenly and substantially reducing the additional supply of feed water to the superheater while greatly diminishing the pressure at the outlet end of the superheater by opening a pressure maintaining element in the bypass line. In this way, a rapid increase of the firing rate is made possible without greatly increasing the risk to the heating surfaces so that the starting up procedure can be shortened.
  • the additional supply of feed water to the superheater results in a continuous flow of feed water in the superheater so that, during this period of time, the generation of steam in the superheater is prevented.
  • the steam generator can be started at the beginning of the starting up procedure with a higher firing rate or the firing rate can be increased earlier or to a greater extent than previously without excessive thermal stresses being applied, particularly to the tubes of the superheater.
  • the enthalpy of the feed water at the outlet from the evaporator will have reached a sufficiently high value, there is a sudden and substantial reduction in the additional supply of feed water to the superheater and a simultaneous opening of the pressure maintaining element.
  • the apparatus of the invention is adapted to cooperate with a steam generator having a feed water inlet line, an evaporator, a plurality of tubes connected in parallel with respect to the flow of a working medium such as feed water, in order to function as a superheater, a bypass line connected to the outlet from the superheater and an adjustable pressure maintaining element in the bypass line.
  • the apparatus includes an additional feed water line which enters the working medium flow system between the evaporator outlet and the superheater inlet and is constructed to carry a flow which is equal to at least percent of the rate of flow of feed water at full load.
  • the additional feed water line is constructed to carry a flow which is equal to at least 20 percent of the rate of flow of feed water at full load there is no risk of confusing the line with a conventional injection line, serving for temperature regulation, since such an injection line would be dimensioned for only approximately 10 percent of the full-load feed water flow rate.
  • flow through the additional feed water line will normally be controlled by a valve operated by hand or by an automatic control system controlling the starting up operation.
  • FIG. I schematically illustrates a steam generator provided with an apparatus according to the invention
  • FIG. 2 illustrates in part a modified steam generator according to the invention
  • FIG. 3 illustrates in part a further steam generator modified according to the invention.
  • the steam generator 1 includes a pres sure vessel 2, the lower part of which is constructed as an evaporator 4 having interwelded, finned tubes and enclosing a combustion chamber 3.
  • a superheater 5 comprising a plurality of tubes which are connected in parallel with respect to a flow of steam through the generator 1 is positioned in the pressure vessel above the combustion chamber 3. For the sake of simplicity only one tube is shown.
  • the lower end of the pressure vessel 2 is provided with a burner 6 which leads into the combustion chamber 3 and is supplied through a duct 8 with compressed combustion air and through a duct 7 with fuel, for example, oil.
  • a manifold 21 is constructed to the outlet end of the superheater surface 5 from which superheated steam can enter a steam turbine 23 via a valve 22.
  • the outlet of the steam turbine 23 is connected by a duct 24 to a mixing position 25 at which partially expanded steam is mixed with the flue gases which are thus cooled.
  • the upper end of the pressure vessel 2 is connected to a duct 26 which leads to a gas turbine 27 in which the mixture of partially expanded steam and flue gas is expanded.
  • the outlet of the gas turbine 27 is connected by a duct 28 to a chimney.
  • the steam turbine 23 and the gas turbine 27 together with a compressor 10 for the combustion air and an electricity generator 9, which can be adapted to operate as a motor, are mounted on a common shaft.
  • a feed waterline 11 which leads from the degasser 16 to the inlet of the evaporator 4 in order to supply a flow of feed water containsa feed water pump 15 and a flow control valve 17.
  • a line 34 branches from the feed water line 11 and connects to a mixing vessel 20 into which the working medium leaving the evaporator 4 is discharged and with which the pipes of the superheater 5 communicate via a manifold 21'.
  • the duct 34 is provided with a valve 35 and is so dimensioned that at least 20 percent of the full-load feed water flow rate is able to flow therethrough.
  • the degasser 16 is supplied with water through a demineralizing apparatus 30.
  • the feed water pump 15 When the steam generator plant is started up, the feed water pump 15 is set into operation and I5 percent of the full-load feed water flow rate is supplied to the steam generator 1 via the control valve 17.
  • the valve 22. upstream of the turbine 23 is closed and the pressure retaining element 32 is slightly opened so that, after flowing through the evaporator 4 and superheater 5, the feed water can be transferred into the bypass line 31.
  • the superheater surface 5 is additionally supplied with a quantity of feed water through the duct 34 and the opened valve 35. This quantity amounts to approximately 35 percent of the full-load feed water flow rate. Allso, the pressure retaining element 32 is adjusted as to provide a full-load working medium pressure of the order of atm. gauge.
  • the burner 6 is then fed with fuel at a rate corresponding approximately to 15 percent of full-load and with air corresponding approximately to 25 percent of full-load.
  • the water temperature in the evaporator 4 rises more rapidly than the temperature of the water in the superheater 5 because the flowrate in the superheater 5 is substantially greater.
  • steam will be generated therein.
  • the generated steam is condensed in the mixing vessel 20 by means of the feed water which is supplied via the duct 34.
  • the valve 35 is rapidly closed and at the same time the pressure retaining element 32 is opened to such an extent that the pressure at the outlet of the superheater 5 is reduced to approximately atm. gauge.
  • This pressure reduction is propagated through the superheater 5 into the evaporator 4 and causes an intensive evaporation of the feed water therein.
  • the resultant steam surge expels the water from the superheater 5 and, owing to the large pressure difference and the large amount of steam suddenly produced, there is no danger of water stagnating in the individual tubes of the superheater 5.
  • the firing rate and the supply of feed water into the evaporator 4 is increased, the pressure at the outlet end of the superheater being raised by appropriate operation of the pressure retaining element 32.
  • the thermal loading of the superheater 5 is reduced.
  • a further advantage of the large excess of air is that the gas turbine assembly 27, 10 runs freely without the supply of energy even after a very short time.
  • the direct supply of a large quantity of feed water to the superheater 5 during the first phase of start-up prevents damage to the superheater 5 by excessive temperatures of the hot flue gases which are carried a considerable way through the combustion chamber 3 by the high excess of air.
  • a steam generator which is constructed without a gas turbine assembly is provided with a liquid separator 40 instead of a mixing vessel 20, as above.
  • a duct 41 is connected to the liquid separator 40 to draw off water and to direct the withdrawn water to a degasser 16.
  • a line 34 branches off from the feed water line 11 and leads to a point between the exit of the steam from the separator 40 and the superheater 5 into the steam line. The starting up method for this steam generator is the same as described above with respect to the steam generator of FIG. 1.
  • a steam generator which is also constructed without a gas turbine assembly has a line 42 which branches from the water chamber of the separator 40.
  • This line 42 is constructed as a circulating line and joins the tube system of the steam generator upstream of the evaporator 4.
  • a circulating pump 43 is also provided immediately upstream of the evaporator 4 so that the working medium which is separated in the separator can be constantly circulated through the evaporator 4.
  • the circulating pump 43 may be disposed in the line 42 itself.
  • An injection line 44 is also provided which connects into the tube system between two superheaters 5a, 5b and branches off from the line 34.
  • the injection line 44 is provided with a valve 45 whose open cross section is adjusted in dependence upon the temperature of the steam discharged from the superheater surface 5b via a suitable control means 46, as is known.
  • the starting up method for this system is also the same as described with reference to the steam generator of FIG. 1, the circulating pump 43 being switched on from the beginning. Circulation of the water from the separator 40 reliably avoids overheating of the evaporator 4.
  • the valve 45 in the injection line 44 is closed during the starting up procedure.
  • a method as set forth in claim 1 which further comprises the steps of supplying the steam generator with fuel at about 15 percent full-load fuel flow rate and with combustion air at about 25 percent full-load combustion air flow rate during said initial step of supplying said first flow.
  • a superheater including a plurality of tubes disposed in parallel with respect to the flow of working medium, a feed inlet for supplying feed water to said evaporator, a bypass line connected to an outlet of said superheater, and an adjustable pressure maintaining element in said bypass line; an additional feed water line connected between an outlet of said evaporator and an inlet of said superheater to supply an additional flow of feed water at least equal to 20 percent of the full-load feed water flow rate to the superheater.
  • said additional feed water line includes an adjustable valve therein for controlling the rate of flow of feed water therein and a mixing vessel therein downstream of said valve, said mixing vessel being connected to said outlet of said evaporator to receive a flow of working medium therefrom.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
US71437A 1969-09-23 1970-09-11 Apparatus and method for starting up a steam generator Expired - Lifetime US3648667A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1432769A CH513361A (de) 1969-09-23 1969-09-23 Verfahren zum Anfahren eines Dampferzeugers

Publications (1)

Publication Number Publication Date
US3648667A true US3648667A (en) 1972-03-14

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US71437A Expired - Lifetime US3648667A (en) 1969-09-23 1970-09-11 Apparatus and method for starting up a steam generator

Country Status (9)

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US (1) US3648667A (es)
BE (1) BE756407A (es)
CA (1) CA921347A (es)
CH (1) CH513361A (es)
DE (1) DE1950104A1 (es)
ES (1) ES383788A1 (es)
FR (1) FR2061239A5 (es)
GB (1) GB1301315A (es)
NL (1) NL6915466A (es)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19504308C1 (de) * 1995-02-09 1996-08-08 Siemens Ag Verfahren und Vorrichtung zum Anfahren eines Durchlaufdampferzeugers
US6192837B1 (en) * 1997-04-23 2001-02-27 Siemens Aktiengesellschaft Once-through steam generator and method for starting up a once-through steam generator
US20130167504A1 (en) * 2010-09-13 2013-07-04 Jan Brückner Method for regulating a short-term power increase of a steam turbine

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH622332A5 (es) * 1977-09-02 1981-03-31 Sulzer Ag

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3368533A (en) * 1965-02-13 1968-02-13 Steinmueller Gmbh L & C Method of starting forced-flow steam producers
US3411485A (en) * 1966-03-04 1968-11-19 Steinmueller Gmbh L & C Steam producing plant and method of operating same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3368533A (en) * 1965-02-13 1968-02-13 Steinmueller Gmbh L & C Method of starting forced-flow steam producers
US3411485A (en) * 1966-03-04 1968-11-19 Steinmueller Gmbh L & C Steam producing plant and method of operating same

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19504308C1 (de) * 1995-02-09 1996-08-08 Siemens Ag Verfahren und Vorrichtung zum Anfahren eines Durchlaufdampferzeugers
US5839396A (en) * 1995-02-09 1998-11-24 Siemens Aktiengesellschaft Method and apparatus for starting up a continuous-flow steam generator
US6192837B1 (en) * 1997-04-23 2001-02-27 Siemens Aktiengesellschaft Once-through steam generator and method for starting up a once-through steam generator
US20130167504A1 (en) * 2010-09-13 2013-07-04 Jan Brückner Method for regulating a short-term power increase of a steam turbine

Also Published As

Publication number Publication date
NL6915466A (es) 1971-03-25
CH513361A (de) 1971-09-30
ES383788A1 (es) 1973-05-01
FR2061239A5 (es) 1971-06-18
GB1301315A (es) 1972-12-29
BE756407A (fr) 1971-03-22
DE1950104A1 (de) 1971-04-22
CA921347A (en) 1973-02-20

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