US3592170A - Apparatus and method for recirculating working medium in a forced flow steam generator - Google Patents

Apparatus and method for recirculating working medium in a forced flow steam generator Download PDF

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Publication number
US3592170A
US3592170A US844576A US3592170DA US3592170A US 3592170 A US3592170 A US 3592170A US 844576 A US844576 A US 844576A US 3592170D A US3592170D A US 3592170DA US 3592170 A US3592170 A US 3592170A
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Prior art keywords
evaporator
water
steam
steam generator
feed water
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US844576A
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English (en)
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Ewald K Burkle
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Sulzer AG
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Sulzer AG
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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
    • F22B29/12—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 operating with superimposed recirculation during starting and low-load periods, e.g. composite boilers

Definitions

  • SHEET 2 0F 2 Inventor: Ew/un K BURMLE 'O EEYS APPARATUS AND METHOD FOR RECIRCULATING WORKING MEDIUM IN A FORCED FLOW STEAM GENERATOR
  • This invention relates to an apparatus and method for recirculating working medium in a forced flow steam generator. More particularly, this invention relates to an apparatus and method for recirculating working medium through an evaporator or a forced flow steam generator.
  • the wall tubes extend continuously over the entire combustion chamber height, the evaporator heating surface has been much larger than is required for the transfer of the evaporation heat. Accordingly, the evaporator tubes had to be protected from heat radiation in the top part of the combustion chamber by preceding tubes of a wall superheater. Apart from the fact that the evaporator and the wall superheater had to be insulated from one another in order to prevent any heat transfer from the wall superheater to the evaporator, and the fact that it has not been a simple matter to mount the wall superheater, screening of part of the evapora tor necessitates the use of large quantities of material which is not used for heat transfer.
  • the invention obviates the above disadvantage.
  • the invention provides a steam generator with an evaporator in which in the top load range of the steam generator at least some of the working medium leaving the evaporator is condensed on at least some of the preheated feed water and is fed, together with the feed water, to the evaporator inlet.
  • the forced flow steam generator for performing this function utilizes a mixer in which some of the working medium leaving the evaporator condenses on at least some of the preheated feed water and is fed together with feed water to the evaporator inlet.
  • the method of the invention is such that the steam generator is operated so that the temperature of the condensate and feed water mixture forming as a result of the condensation of the working medium is kept at a temperature about l-2U" C. below the saturated steam temperature. This safety margin is necessary to prevent the water in the mixer from evaporating in the event of a sudden pressure drop, and to prevent steam being fed to the circulating pump.
  • the mixer is connected to a water chamber of a water separator via a line while a bypass line equipped with a control and nonreturn valve means is provided between the evaporator outlet and the mixer to bypass the water separator.
  • a bypass line equipped with a control and nonreturn valve means is provided between the evaporator outlet and the mixer to bypass the water separator.
  • the mixer is combined with the water separator.
  • the mixer forms part of the water separator and the line coming from the water preheater is divided into two branches, one of which leads into the separator above the water level while the other branch leads into the separator below the water level.
  • a distributor is also provided at the point where the line branches to control the path of flow.
  • the invention thus provides a method of operating a forced flow steam generator which is constructed for subcritical pressure.
  • the invention further provides a steam generator which is constructed with a water separator connected to the evaporator outlet and to the evaporator inlet so that the working medium can be recycled, at part load, via the water separa' tor and a circulating pump to the evaporator inlet.
  • the combustion chamber walls of the steam generator are formed of parallel connected vertical evaporator tubes which extend over the entire combustion chamber height.
  • FIG. 1 illustrates a flow diagram of a forced flow steam generator utilizing a mixer separate from a separator according to the invention
  • FIG. 2 illustrates a flow diagram of a modified forced flow steam generator according to the invention.
  • the steam generator is constructed with a preheater 2, an evaporator 6, and a superheater 1] which are interconnected in the flow path of a working medium as well as any other known components as is known.
  • the preheater 2 is connected to a feed pump (not shown) which serves to deliver feed water to the preheater 2 via a feed water control valve l and via suitable lines to a mixer 3 at the opposite side which receives the feed water from the preheater.
  • the mixer 3 is connected via a circulating pump 4 to the inlet 5 of the evaporator 6 in order to deliver the feed water thereto.
  • the evaporator 6 is constructed of parallel connected vertical evaporator tubes which serve to define the walls of a combustion chamber within the steam generator by extending over the entire combustion chamber height.
  • a water separator 8 is connected between the outlet 7 of the evaporator 6 and a line [0 which leads to the superheater ll so that water can be separated from the working medium flowing from the evaporator 6 to the superheater 11.
  • water separator chamber outlet is also connected by a line 9 containing a nonreturn valve M to the mixer 3 in order to direct the separated water to the mixer 3.
  • a suitable line hav ing a valve therein is also connected to the bottom of the water separator 8 in order to act as a drain or for other purposes as is known.
  • the outlet 7 of the evaporator 6 is also connected to the mixer 3 via a bypass line l2 having a control valve 13 and u nonreturn valve 14 therein.
  • the control valve 13 functions to control a flow of steam through the line 12 to the mixer 3 while the nonreturn valve [4 prevents a return flow from the mixer 3 to the evaporator outlet 7.
  • the mixer 3 thus serves as a means for condensing at least some of the working medium leaving the evaporator outlet 7 on at least some of the pre' heated feed water for subsequent feeding with the feed water to the evaporator inlet 5,
  • feed water is delivered to the preheater 2 via the feed water control valve l in order to be preheated as is known.
  • the preheated feed water flows to the mixer 3 and from there is fed by the circulating pump 4 to the inlet 5 of the evaporator 6.
  • the mixture of steam and water at the evaporator outlet 7 is fed to the water separator 8 where the water and steam are separated.
  • the separated water then flows through the line 9 to the mixer 3 and is fed to the evaporator inlet 5 together with the preheated feed water by means of the circulating pump 4
  • the steam passes from the separator 8 via the line 10 to the su' perheater H and is superheated to the required temperature and then flows to a turbine (not shown).
  • the lfthe steam generator is operated with a steam temperature at the outlet 7 of the evaporator 6 above saturated steam tern perature, part of the generated steam is fed to the mixer 3 via a bypass line 12 with the remainder being fed to the water separator.
  • the amount of steam fed to the mixer is controlled by the control valve 13 according to the amount of water required to be recirculated to the evaporator 6.
  • the mixture temperature in the mixer 3 forms a limit for the amount of steam recycled, such temperature being kept between 10 and C below the saturated steam temperature.
  • any suitable control means can be used to operate the control valve 13 in response to the amount of steam required.
  • 3 quantity of working medium is continually fed from the evaporator outlet 7 to the mixer 3 in order to act as a barrier against any return How of water from the mixer 3. Any return flow of water from the mixer 3 to the separator 8 is also prevented by the nonreturn valve 14.
  • a steam generator having a pressure of about 200 atmospheres gauge at the evaporator outlet 7 will be taken as a basis.
  • superheated steam at a temperature of 380-390 C leaves the evaporator 6, having been generated at a saturated steam temperature of about 365 C, the feed water tempera ture being 260 C. in this load range, part of the steam generated is fed to the mixer 3.
  • the temperature difference between the preheated feed water and the recycled steam al' lows condensation of about percent of the steam generated without dropping below the safety margin in relation to the saturated steam temperature in the mixer 3. Consequently, the steam generator can be operated with a l.3 recirculation in the evaporator.
  • the water separator 8 and the mixer 3 are separate components of the steam generator or are combined to form a unit.
  • the line 18 coming from the water preheater 2 is divided into two branches 19, 20, the top branch [9 of which leads into the water separator 8 above the water level while the bottom branch 20 leads into the separator 8' below the water level.
  • is provided to control the apportionment of the feed water between the branches I9, 20 and is controlled in dependence on the temperature of the working medium leaving the water chamber of the separator 8.
  • a temperature sensitive element 23 is connected in the line 22 and is connected to a controller 24, the output of which is fed to the distributor 21 in order to adjust the distributor 21 to control the paths of flow.
  • a pressure sensitive element 25 is also connected in the line 22in order to adjust the temperature set value in response to the sensed pressure via a function transmitter 26.
  • a steam generator having an evaporator parallel connected evaporator tubes defining and extending over the height of a combustion chamber, said evaporator further including an inlet and an outlet, means for feeding preheated feed water to said evaporator inlet, and a water separator connccted to said evaporator between said outlet and said inlet for recycling working medium through said evaporator; means for condensing at least some of the steam leaving said evaporator outlet on at least some of the preheated feed water for subsequent feeding with the preheated feed water to said evaporator inlet.
  • said means for condensing is a mixer connected to said evaporator outlet for receiving steam therefrom, to said water separator to receive water therefrom and to said means for feeding preheated feed water.
  • bypass line is connected between said evaporator outlet and said mixer to bypass said water separator, said bypass line hav ing a control valve therein for controlling the flow of steam; and a line is connected between said water separator and mixer to convey water therebetween.
  • said means for condensing includes a line between said means for feeding preheated feed water, a pair of branch lines connected between said line and said water separator, one of said branch lines being connected to said water separator above the water level therein and the other of said branch lines being connected to said water separator below the water level therein, and a distributor between said line and said branch lines for controlling the feed water between said branch lines.
  • said water separator has an outlet connected to said evaporator inlet for feeding working medium thereto and wherein said means for condensing further includes a temperature sensitive element connected to said separator outlet and said distributor for controlling said distributor in response to the temperature in said separator outlet.
  • a method of operating a forced flow steam generator constructed for subcritical pressure and having a water separator connected to and between an evaporator inlet and outlet therein comprising the steps of feeding preheated feed water to the evaporator inlet,

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)
US844576A 1968-07-25 1969-07-24 Apparatus and method for recirculating working medium in a forced flow steam generator Expired - Lifetime US3592170A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19681751761 DE1751761B2 (de) 1968-07-25 1968-07-25 Verfahren zum unterkritischen betrieb eines zwanglaufdampferzeugers mit arbeitsmittelrueckfuehrung

Publications (1)

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US3592170A true US3592170A (en) 1971-07-13

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US844576A Expired - Lifetime US3592170A (en) 1968-07-25 1969-07-24 Apparatus and method for recirculating working medium in a forced flow steam generator

Country Status (9)

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US (1) US3592170A (de)
BE (1) BE736610A (de)
CH (1) CH511398A (de)
DE (1) DE1751761B2 (de)
ES (1) ES369796A1 (de)
FR (1) FR2013700A1 (de)
GB (1) GB1280234A (de)
NL (1) NL6910880A (de)
SE (1) SE343670B (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3690303A (en) * 1969-12-24 1972-09-12 Sulzer Ag Forced circulating steam generator and method of generating steam
FR2211650A1 (de) * 1972-12-20 1974-07-19 Sulzer Ag
US20090071419A1 (en) * 2005-04-05 2009-03-19 Joachim Franke Steam Generator
US20100288210A1 (en) * 2007-11-28 2010-11-18 Brueckner Jan Method for operating a once-through steam generator and forced-flow steam generator
US20170363342A1 (en) * 2016-06-17 2017-12-21 Panasonic Intellectual Property Management Co., Ltd. Evaporators, methods for defrosting an evaporator, and cooling apparatuses using the evaporator
US20180266673A1 (en) * 2015-01-23 2018-09-20 Siemens Aktiengesellschaft Waste-heat steam generator

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3038453A (en) * 1957-02-07 1962-06-12 Combustion Eng Apparatus and method for controlling a forced flow once-through steam generator
US3411484A (en) * 1966-03-05 1968-11-19 Steinmueller Gmbh L & C Method of and apparatus for starting and stopping forced circulation boilers

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3038453A (en) * 1957-02-07 1962-06-12 Combustion Eng Apparatus and method for controlling a forced flow once-through steam generator
US3411484A (en) * 1966-03-05 1968-11-19 Steinmueller Gmbh L & C Method of and apparatus for starting and stopping forced circulation boilers

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3690303A (en) * 1969-12-24 1972-09-12 Sulzer Ag Forced circulating steam generator and method of generating steam
FR2211650A1 (de) * 1972-12-20 1974-07-19 Sulzer Ag
US20090071419A1 (en) * 2005-04-05 2009-03-19 Joachim Franke Steam Generator
US8297236B2 (en) * 2005-04-05 2012-10-30 Siemens Aktiengesellschaft Steam generator
US20100288210A1 (en) * 2007-11-28 2010-11-18 Brueckner Jan Method for operating a once-through steam generator and forced-flow steam generator
US9482427B2 (en) * 2007-11-28 2016-11-01 Siemens Aktiengesellschaft Method for operating a once-through steam generator and forced-flow steam generator
US20180266673A1 (en) * 2015-01-23 2018-09-20 Siemens Aktiengesellschaft Waste-heat steam generator
US10451267B2 (en) * 2015-01-23 2019-10-22 Siemens Aktiengesellschaft Waste-heat steam generator
US20170363342A1 (en) * 2016-06-17 2017-12-21 Panasonic Intellectual Property Management Co., Ltd. Evaporators, methods for defrosting an evaporator, and cooling apparatuses using the evaporator
US10345028B2 (en) * 2016-06-17 2019-07-09 Panasonic Intellectual Property Management Co., Ltd. Evaporators, methods for defrosting an evaporator, and cooling apparatuses using the evaporator

Also Published As

Publication number Publication date
BE736610A (de) 1970-01-26
SE343670B (de) 1972-03-13
FR2013700A1 (de) 1970-04-03
DE1751761B2 (de) 1973-09-06
CH511398A (de) 1971-08-15
GB1280234A (en) 1972-07-05
NL6910880A (de) 1970-01-27
DE1751761A1 (de) 1971-11-18
ES369796A1 (es) 1971-07-16

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