US3892191A - Vapor generating system in which recirculated flue gases are injected into the combustion air stream of a steam generator - Google Patents

Vapor generating system in which recirculated flue gases are injected into the combustion air stream of a steam generator Download PDF

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Publication number
US3892191A
US3892191A US469261A US46926174A US3892191A US 3892191 A US3892191 A US 3892191A US 469261 A US469261 A US 469261A US 46926174 A US46926174 A US 46926174A US 3892191 A US3892191 A US 3892191A
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United States
Prior art keywords
air
gases
duct means
openings
generating system
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Expired - Lifetime
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US469261A
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English (en)
Inventor
Jr Robert P Welden
Walter P Gorzegno
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Foster Wheeler Inc
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Foster Wheeler Inc
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Priority to US469261A priority Critical patent/US3892191A/en
Priority to CA221,511A priority patent/CA1018846A/en
Priority to ES436345A priority patent/ES436345A1/es
Priority to JP50051943A priority patent/JPS50146943A/ja
Application granted granted Critical
Publication of US3892191A publication Critical patent/US3892191A/en
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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 
    • F23C9/00—Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber

Definitions

  • This invention relates to a vapor generating system in which recirculated flue gases are injected into the com bustion air stream ofa steam generator, and the quantities of injected flue gases and combustion air are measured.
  • the vapor generating system of the present invention includes duct means connecting the interior of a furnace section with a source of air and a plurality of mixing pipes disposed in said duct means. Flue gases are passed from said furnace section into said mixing pipes, with the mixing pipes having outlets for permitting the discharge of said gases into the path of air flowing through said duct means to mix said gases and air before they are introduced into said furnace section.
  • a plurality of metering pipes are disposed in the air duct, and apparatus is provided which cooperates with the mixing pipes and the metering pipes to enable the quantities of gases and air to be respectively measured.
  • FIG. I is a schematic view of an example of a vapor generator incorporating the system of the present invention.
  • FIG. 2 is an enlarged partial perspective view depicting a portion of a wall of the vapor generator of FIG. l;
  • FIG, 3 is a partial enlarged sectional view taken along the line 33 of FIG. 1;
  • FIG. 4 is an enlarged sectional view taken along the line 4l4l of FIG. ll;
  • FIG. 5 is an enlarged partial perspective view showing a section of the vapor generator of FIG. I.
  • FIG. 6 is an enlarged, fragmentary sectional view of a portion of the arrangement of FIG. 5.
  • one arrangement of a vapor generator of the present invention is broadly indicated by the reference numeral MI and comprises a vertically extending rectangular-shaped radiant furnace portion 12 having a bottom hopper l4 and an upper outlet area 16 to which is connected a horizontally extending and downwardly extending convection section 1% having an outlet 20.
  • MI the reference numeral
  • hot gases flow upwardly in the furnace portion 12 through the outlet area l6, and downwardly through the convection section 1%, whereby they exit through the outlet 20 for further treatment in a manner to be described in detail later.
  • the furnace portion I2 is in the form of an upright rectangular enclosure extending vertically from the floor of the generator to a roof and defined by front and rear walls 24 and 26, and a pair of side walls, one of which is shown by the reference numeral 28.
  • a floor 30 connects the upper section of the furnace portion 12 to the convection section 118 with the latter being defined by a front wall panel 32, a rear wall panel 34, and a pair of side walls, one of which is shown by the reference numeral 36.
  • a vertical partition wall divides the convection section l8 into front and rear gas passes and that the convection section contains a plurality of superheater tubes, reheater tubes, and economizer tubes.
  • the partition wall and tubes are not shown or described in the present invention since they do not form a part of the present invention, and since they are described in detail in US. Pat. No. 3,556,059, assigned to the assignee of the present invention, the disclosure of which is incorporated by reference.
  • FIG. 2 depicts the membranetype wall that is used throughout the generator, including the walls 24-, 26, 28, 32, 34, and 36, as well as the floor 30.
  • the walls are formed by welding together a plurality of finned tubes 38 along their lengths so that the enclosures defined by the various walls are substantially gas tight.
  • an insulating wall of a suitable insulating material would be provided adjacent the above-mentioned membrane-type walls, and externally thereof. For the convenience of presentation, these insulating walls have been omitted from the present drawings.
  • Water is passed through the tubes of each of the above-mentioned walls and is routed in a predetermined flow path by means of suitable headers, downcomers, etc., in a manner so that it is gradually turned into steam by virtue of the heat generated in the furnace portion l2, after which the steam is superheated and collected in a conventional manner.
  • a duct 40 is connected to the convection section outlet 2% for receiving the flue gases passing from the convection section and directing a portion of same into an air heater 42.
  • the air heater 42 is provided with an inlet 42a for receiving absorption from atmosphere, and an outlet 42b for passing the hot gases entering therein to a stack or the like, with the air heater providing a heat exchange between the gases and the air before they exit therefrom, in a conventional manner.
  • a wind box 46 is located at the lowerportion of the furnace portion 12 and supplies air, to the furnace portion 12 and typically includes front and rear plates 48 and 50 which are spaced from the corresponding portions of the front and rear walls 24 and 26, respectively, of the furnace portion.
  • a plurality of burners 52 discharge through openings formed in the furnace walls 24 and 26. The details of the burners 52 will be described later. 7
  • a duct 56 connects the air heater 42 to the lower section of the wind box 46 for supplying the preheated air from the air heater 42 to the wind box 46.
  • a duct 60 connects the duct 40 to the lower portion of the duct 56 for supplying a portion of the hot flue gases from the convection section outlet 20 to the duct 56 under the force of a fan 62 disposed in the duct 60.
  • a mixing Zone shown in general by the reference numeral 64 is defined in the duct 56 which mixes the combustion air from the preheater 42', and the recirculated flue gases from the duct 60.
  • the details of the mixing zone 64 will be described later.
  • FIG. 3 depicts the burners 52 and their positions relative to the furnace portion 12 in detail.
  • the burners are arranged in four vertical rows of four burners per row, it being understood that the number of burners and their particular pattern can vary.
  • the burners 52 are of a conventional design and form no portion of the present invention, they are shown j only in general, with it being understood that they include an inlet for receiving fuel, which can be in liquid or gaseous form, or which can be a mixture of pulverized fuel and primary air.
  • An annular space 68 is defined between the throat end of each burner 52 and its corresponding opening in the wall 24 for reasons that will be described in detail later.
  • the air-gas mixture from the mixing zone 64 will be passed into the wind box 46, through the annular spaces 68, and into the furnace portion 12, as shown by the flow arrows in FIG. 3, to reduce the formation of nitric oxides and, in the event a solid fuel is used, to also reduce the slag deposits, as discussed above. It is understood that in some installations, overfire ports 100 may be provided through which a portion of the air-gas mixture would pass into the furnace portion 12.
  • the details of the structure defining the mixing zone 64 as well as apparatus for measuring the fluid flow are discharged in two directions in the duct 56 from each pipe and perpendicular to the path of the air flowing through the duct 56. As a result, a relatively uniform mixture of gases and air is formed for passage into the wind box 46.
  • one row of three metering pipes 74 are disposed in the inlet portion of the mixing zone 64 as shown in FIG. 5.
  • Eachpipe 74 is closed at both ends and is provided with an opening 76 facing the upstream portion of duct 56 to measure total pressure of the air in the duct, which equals the velocity pressure plus the static pressure.
  • An additional opening 78 is provided through each pipe 74 in a spaced relation to the opening 76 to measure static pressure of the air in the duct 56.
  • a pair of tubes 80, and 82 each have an end portion extending within each pipe 74 and registering with the opening 76 and 78, respectively, with only the tubes associated with one of the pipes 74 being shown for the convenience of presentation.
  • the tubes 80 and 82 are connected at their other ends to a flow meter 84 to transfer the respective pressures from the tubes to the flow meter. Since the pressure of the air in the tube 80 represents the total pressure of the air in the duct 56, i.e.. the velocity pressure plus the static pressure,
  • one end portion of an exit tube 89 is connected to an openingprovided through at least one of the pipes 70 so that it communicates with the interior thereof, and a tube 90 is connected to the tube 89 in registry therewith. Also,
  • an end portion of a tube 92 extends through an opening provided in the duct 60 and in the path of the recirculated gases in the latterduct.
  • the other ends of the tubes 90 and 92 are connected to a flow meter 94, and since the pressure in the tube 92 represents the static pressure of the gases in the duct 60, and the pressure in the tube 90 represents the static pressure of the gases leaving the exit tube the flow meter 94 can be designed to provide an indication of the gas flow rate based on a difference in static pressures in a similar manner to that discussed above with respect to the flow meter 84.
  • tubes 89 and 90 can be provided at more than one of the pipes 70 and that a plurality of tubes 92 can be in communication with a plurality of openings formed in the duct 60. Also, the tubes 89 and 92 can be designed to register with a plurality of openings formed in the tubes 70 and the duct 60, re-
  • the flow meter 94 would respond to differences of average readings in determining the gas flow.
  • the arrangement of the present invention enables the recirculated flue gases to be uniformly mixed with the combustion air and utilized to reduce the formation of nitric oxides and, when solid fuels are used, to also reduce slag deposits.
  • the present arrangement provides for flow measurements of the recirculated flue gases and the combustion air, while reducing the ducting requirements and the pressure losses when compared to those arrangements using oriflce meters, air foils, venturis and the like.
  • a vapor generating system comprising a furnace section, duct means connecting the interior of said furnace section with a source of air, a plurality of mixing pipes disposed in said duct means, and additional duct means for introducing combustion gases from the outlet of said furnace section into said mixing pipes, said mixing pipes having a plurality of slots extending therethrough for discharging said gases into the path of air flowing through said duct means in a direction perpendicular to the direction of the flow of said air to mix said gases and air before they are introduced into said furnace section.
  • a vapor generating system comprising a furnace section, duct means connecting the interior of said furnace section with a source of air, a plurality of mixing pipes disposed in said duct means, additional duct means for introducing combustion gases from the outlet of said furnace section into said mixing pipes, said mixing pipes having outlets for permitting the discharge of said gases into the path of air flowing through said duct means to mix said gases and air before they are introduced into said furnace section, said additional duct means and at least one of said mixing pipes having an opening formed therein, and means registering with said openings and responsive to the respective gas pressures at the openings for enabling the flow rate of said gases through said duct means to be determined.
  • said means registering with said openings comprises a tube having one end registering with one of said openings, a tube having one end registering with the other of said opening, and a flow meter connected to the other ends of said tubes and responsive to the respective fluid pressures in said tubes.
  • a vapor generating system comprising a furnace section, duct means connecting the interior of said fur nace section with a source of air, at least one metering pipe disposed in said duct means and having at least one opening in the direct path of air flow through said duct means and at least one additional opening spaced from said one opening out of the direct path of air flow through said duct means, and means registering with said openings and responsive to the respective air pressures at the openings for enabling the flow rate of said air through said duct means to be determined.
  • said means registering with said openings comprises a tube having one end registering with one of said openings, a tube having one end registering with said additional opening and a flow meter connected to the other ends of said tubes and responsive to the respective fluid pressures in said tubes.
  • the generating system of claim 6 further comprising a plurality of mixing pipes disposed in said duct means, and additional duct means for introducing combustion gases from said furnace section into said mixing pipes, said mixing pipes having outlets for permitting the discharge of said gases into the path of air flowing through said duct means to mix said gases and air before they are introduced into said furnace section.
  • a plurality of openings are provided through at least one of said walls for permitting the mixture of gases and air to enter said furnace section and further comprising a plurality of burners mounted relative to said wall for discharge through said openings.
  • outlets are in the form of a plurality of slots extending through said mixing pipes and adapted to discharge said gases in a direction perpendicular to the direction of said air flow.
  • said means registering with said latter openings comprises a tube having one end registering with one of said latter openings, a tube having one end registering with the other of said latter opening, and a flow meter connected to the other ends of said tubes and responsive to the respective fluid pressures in said tubes.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Combustion Of Fluid Fuel (AREA)
US469261A 1974-05-13 1974-05-13 Vapor generating system in which recirculated flue gases are injected into the combustion air stream of a steam generator Expired - Lifetime US3892191A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US469261A US3892191A (en) 1974-05-13 1974-05-13 Vapor generating system in which recirculated flue gases are injected into the combustion air stream of a steam generator
CA221,511A CA1018846A (en) 1974-05-13 1975-03-07 Vapor generating system in which recirculated flue gases are injected into the combustion air stream of a steam generator
ES436345A ES436345A1 (es) 1974-05-13 1975-04-07 Un sistema mejorado para generacion de vapor.
JP50051943A JPS50146943A (enrdf_load_stackoverflow) 1974-05-13 1975-04-28

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US469261A US3892191A (en) 1974-05-13 1974-05-13 Vapor generating system in which recirculated flue gases are injected into the combustion air stream of a steam generator

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US3892191A true US3892191A (en) 1975-07-01

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US (1) US3892191A (enrdf_load_stackoverflow)
JP (1) JPS50146943A (enrdf_load_stackoverflow)
CA (1) CA1018846A (enrdf_load_stackoverflow)
ES (1) ES436345A1 (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4257357A (en) * 1978-01-16 1981-03-24 Foster Wheeler Energy Corporation Furnaces
US6606969B2 (en) * 2000-01-14 2003-08-19 Wsowarmeprozesstechnik Gmbh Tubular oven
US20130233255A1 (en) * 2010-07-26 2013-09-12 Chao Hui Chen Furnace Tube Arrangement for Steam Generator

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1789401A (en) * 1929-01-08 1931-01-20 Babcock & Wilcox Co Air heater
US1837713A (en) * 1926-03-09 1931-12-22 Fuller Lehigh Co Furnace and method of operating the same
US2229643A (en) * 1937-01-02 1941-01-28 Superheater Co Ltd Method and apparatus for controlling temperature of superheated steam
US2926636A (en) * 1953-11-18 1960-03-01 Bailey Meter Co Steam temperature control

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3781162A (en) * 1972-03-24 1973-12-25 Babcock & Wilcox Co Reducing nox formation by combustion

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1837713A (en) * 1926-03-09 1931-12-22 Fuller Lehigh Co Furnace and method of operating the same
US1789401A (en) * 1929-01-08 1931-01-20 Babcock & Wilcox Co Air heater
US2229643A (en) * 1937-01-02 1941-01-28 Superheater Co Ltd Method and apparatus for controlling temperature of superheated steam
US2926636A (en) * 1953-11-18 1960-03-01 Bailey Meter Co Steam temperature control

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4257357A (en) * 1978-01-16 1981-03-24 Foster Wheeler Energy Corporation Furnaces
US6606969B2 (en) * 2000-01-14 2003-08-19 Wsowarmeprozesstechnik Gmbh Tubular oven
US20130233255A1 (en) * 2010-07-26 2013-09-12 Chao Hui Chen Furnace Tube Arrangement for Steam Generator
US9062877B2 (en) * 2010-07-26 2015-06-23 Doosan Babcock Limited Furnace tube arrangement for steam generator

Also Published As

Publication number Publication date
JPS50146943A (enrdf_load_stackoverflow) 1975-11-25
ES436345A1 (es) 1977-04-01
CA1018846A (en) 1977-10-11

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