EP0672861A1 - Générateur de chaleur, en particulier pour la production de vapeur, du type à faible NOX, avec des chambres multiples formées par des tubes, utilisant des brûleurs radiants - Google Patents

Générateur de chaleur, en particulier pour la production de vapeur, du type à faible NOX, avec des chambres multiples formées par des tubes, utilisant des brûleurs radiants Download PDF

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Publication number
EP0672861A1
EP0672861A1 EP94104179A EP94104179A EP0672861A1 EP 0672861 A1 EP0672861 A1 EP 0672861A1 EP 94104179 A EP94104179 A EP 94104179A EP 94104179 A EP94104179 A EP 94104179A EP 0672861 A1 EP0672861 A1 EP 0672861A1
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EP
European Patent Office
Prior art keywords
walls
chambers
membrane
radiant
fitted
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.)
Withdrawn
Application number
EP94104179A
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German (de)
English (en)
Inventor
Vincenzo Recchi
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.)
Aem Azienda Energetica Municipale
Tecnars Srl Tecnologie Avanzate Ricerca & Sviluppo
Original Assignee
Aem Azienda Energetica Municipale
Tecnars Srl Tecnologie Avanzate Ricerca & Sviluppo
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.)
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Publication date
Application filed by Aem Azienda Energetica Municipale, Tecnars Srl Tecnologie Avanzate Ricerca & Sviluppo filed Critical Aem Azienda Energetica Municipale
Priority to EP94104179A priority Critical patent/EP0672861A1/fr
Publication of EP0672861A1 publication Critical patent/EP0672861A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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

Definitions

  • the present invention relates to a heat generator, particularly for steam generation, of the fluid-tube type that uses a plurality of radiant gas burners, made of ceramic fiber or the like, which are associated with contoured means that allow to divide the combustion chamber into contiguous chambers having such a shape that they are substantially shielded from each other.
  • porous ones made of ceramic fiber which are constituted by a microporous matrix of small-diameter fibers of ceramic materials, through which the appropriately premixed gaseous fuel and air flow.
  • Ignition occurs on the outermost surface without producing a visible flame: only a bright orange incandescence can be detected.
  • the innermost part of the ceramic layer remains at the temperature of the reagents, whereas the surface stabilizes at 900-1100 o C, depending on the thermal environment that affects the burner.
  • the thermal power produced is transmitted mainly (over 50%) by radiation; this characteristic of radiating much of the energy generated by combustion, combined with uniformity both in energy distribution and in the distribution and excellent mixing of fuel and comburent, reduces the maximum combustion temperature and accordingly reduces the emission of nitric oxides.
  • nitric oxide emission levels generally observed with ceramic burners in tested applications are between 10 and 20 ppmv, i.e. 80% lower than those detected in conventional burners.
  • the combustion mechanisms taking place on the surface of the burner furthermore considerably reduce CO emissions.
  • Ceramic-fiber burners can be produced in various shapes: small burners are generally shaped like cylindrical tubes with a hemispherical end. Larger burners, generally used for applications in boilers with a fluid-tube furnace, are generally constituted by modular segments joined by means of ceramic flanges and having a flattened cross-section, typically rhomboidal or elliptical. Since the thermal power produced by an individual burner is directly proportional to the combustion surface, in theory said surface can extend indefinitely. In actual fact, the other functions of the burner (fuel distribution) and of the heat generator (heat exchange with the heat transfer medium) must be considered.
  • ceramic-fiber radiant burners have the following advantages for the user:
  • conventional heat generators are typically constituted by a combustion chamber (radiant section), where the fuel oxidation reactions take place substantially until they are complete, and by a convective section, where the high-temperature combustion products transfer their enthalpy with a predominantly convective process.
  • the aim of the present invention is to provide a heat generator of the fluid-tube type that uses radiant gas burners located within multiple contiguous chambers and is conceived and structured so as to allow, by virtue of the particular arrangement of its burners and irradiation chambers, to utilize in the best possible manner the radiant emission of the individual ceramic burners, to avoid as much as possible mutual irradiation among the burners of the individual cells, and to contain dimensions without negatively affecting the efficiency and uniformity of the radiant emissions.
  • Another object of the invention is to provide a structure with multiple chambers for said heat generator, conceived so as to optimize the internal spaces of the combustion chamber and of the entire generator, allowing to achieve very high efficiency levels combined with easy manufacture and assembly of the fluid tubes.
  • Another object of the invention is to provide a multiple-chamber heat generator which is conceived so as to also allow the use of radiant burners made of materials other than ceramic fiber and so as to also allow changes in the shape and mutual placement of the individual radiant cells in order to shield said cells substantially completely.
  • a heat generator of the convection tube-nest type connected to two or more horizontal cylindrical bodies which is provided with the associated economizer and steam superheater and uses a plurality of radiant gas burners made of ceramic fiber or the like, said generator having, according to the present invention, a quincuncial arrangement of said radiant burners and a cellular structure, within the combustion chamber, formed by means of walls which are constituted by subvertical tubes provided with membranes and are shaped so as to form wide alternating curves with such curvature radii as to form, around each burner, a combustion chamber having a substantially quadrangular shape, said chambers being all mutually contiguous and arranged quincuncially, the tubes that form said membrane-fitted walls being instead connected to said horizontal cylindrical bodies so as to form the evaporation walls of the radiant section with uniform irradiation from both sides of said walls.
  • said membrane-fitted walls forming the quincuncial combustion chambers have the shape of a vertical plane which is curved alternately in two directions so as to have straight wall portions arranged alternately in opposite pairs that are such as to allow the straight wall portions of two opposite membrane-fitted walls to form substantially quadrangular chambers mutually contiguous and arranged symmetrically with respect to the vertical median plane of the generator, the alternating curves between each pair of straight and contiguous portions of said walls being formed with angles wider than 90 o and so that the bisecting line of said angles is horizontal or tilted up to 30 o with respect to the horizontal.
  • curvature points of a membrane-fitted wall can furthermore be shifted downward with respect to those of the opposite wall, so as to allow, by placing said opposite points mutually adjacent, a partial overlap of said points that can fully shield each pair of contiguous chambers; furthermore, a membrane-fitted tube wall, suitable to form three fume turns, is provided between said radiant section and the convective section.
  • the generator illustrated therein is, as regards its general structure, of a known type, whereas the particular arrangement of the burners, the structure of the combustion chambers and part of the convective section constitute the improvement according to the present invention.
  • said heat generator is of the type having subvertical fluid tubes with cylindrical bodies with natural circulation and the associated superheater and economizer tube nests.
  • Said generator is in fact constituted by a boiler with a jacket 1 made of insulating material and accommodating, in an upward region, a hollow longitudinal cylindrical body 2; the upper ends of the tube nest 3 and other walls formed with membrane-fitted tubes, which will be better described hereinafter, are connected to the lower end of said body 2.
  • the generator is furthermore provided with steam superheating tubes 4, possibly symmetrical (figure 1), arranged in multiple rows connected to respective distribution manifolds: an upper one 5 and a lower one 5a.
  • the rear wall B (figures 2-3) of the generator has a conventional fume collecting box 6 connected to a water preheater-economizer 7.
  • a stack 8 for removing the fumes is also provided on the rear side B and laterally to the generator.
  • the improvement according to the invention consists in using, within the combustion chamber designated by the letter C in figure 1, a plurality of radiant gas burners of a known type, preferably having an oval or elliptical transverse cross-section, which are arranged so as to form a quincunx of modulus 2+1+2+1 etc. and, more generally, n+(n-1)+n+ etc.
  • the five radiant burners 9 have the same dimensions, are arranged so that their axes are mutually parallel and substantially equidistant from each other; their quincuncial arrangement allows to provide heat generators of the same type with a wide range of power ratings, utilizing in the best possible manner the characteristics of surface combustion and the uniformity in the distribution of the heat flux.
  • Said burners 9 are then individually enclosed in radiation chambers 11 which are formed by evaporation walls 10, each of which is constituted by subvertical tubes arranged side by side and mutually connected by fins so as to form fume-tight continuous walls.
  • Each finned wall 10 is substantially shaped like a broken line or like a line with alternating curvatures so as to form, by means of two pairs of mutually opposite walls 10, the individual chambers 11, each of which encloses a burner 9.
  • curvature angles ⁇ between two contiguous straight segments 10a are identical for all the membrane-fitted walls 10 and are wider than 90 o ; the bisecting line of the individual angles is horizontal or even inclined up to 30 o with respect to the horizontal.
  • the individual radiation chambers are therefore constituted by four straight portions 10a of two opposite membrane-fitted walls 10; these portions form substantially quadrangular or rhomboidal chambers which are also arranged quincuncially and are substantially completely shielded from each other since free space is reduced to a few millimeters in the regions 12 between each pair of opposite angles ⁇ ; furthermore the path of the fumes is not interrupted between two vertically contiguous chambers.
  • the particular quincuncial arrangement of the burners 9 and of the radiant chambers 11 allows in practice to maximally optimize the coupling of the burners and the boiler, placing radiant surfaces and irradiated surfaces opposite to each other along the maximum extension that is compatible with the other functions of the burners and of the heat generator.
  • a shielding wall 13 is interposed between the chambers 11 and the tube nest 3 and is formed by vertical tubes mutually connected by fins, so as to prevent the escape of the fumes released by the radiation chambers.
  • a finned wall 14 with vertical tubes that also prevents the escape of the fumes. Therefore, these finned walls 13 and 14, together with the evaporation walls 10 that form the chambers 11, allow to obtain three fume paths: one inside the radiant chambers 11, another between the chambers and the inner membrane-fitted wall 13 (in the opposite direction with respect to the preceding path) and the third one through the tubes of the evaporation section 3. These paths are designated by the letters D-E-F in figure 4.
  • the quincuncial arrangement of the radiation chambers also allows to fully shield two contiguous chambers, lowering the curvature point of one evaporation wall with respect to the opposite one formed by the opposite evaporation wall and then placing them mutually adjacent so as to achieve a partial overlap that can totally shield the two contiguous cells.
  • the quincuncial arrangement of the burners and of the associated radiation chambers can also be provided in generators having three cylindrical bodies, as shown in figure 4; in the same manner, the same arrangement can be used within heat generators with a D-shaped structure in which the upper cylindrical body 2 and the lower one 2a are arranged laterally and in which the convective tube nest is arranged only on one side of the generator.
  • the heat generator according to the present invention can be used as a heat generator for heating heat-dissipating fluids.
EP94104179A 1994-03-17 1994-03-17 Générateur de chaleur, en particulier pour la production de vapeur, du type à faible NOX, avec des chambres multiples formées par des tubes, utilisant des brûleurs radiants Withdrawn EP0672861A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP94104179A EP0672861A1 (fr) 1994-03-17 1994-03-17 Générateur de chaleur, en particulier pour la production de vapeur, du type à faible NOX, avec des chambres multiples formées par des tubes, utilisant des brûleurs radiants

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP94104179A EP0672861A1 (fr) 1994-03-17 1994-03-17 Générateur de chaleur, en particulier pour la production de vapeur, du type à faible NOX, avec des chambres multiples formées par des tubes, utilisant des brûleurs radiants

Publications (1)

Publication Number Publication Date
EP0672861A1 true EP0672861A1 (fr) 1995-09-20

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EP94104179A Withdrawn EP0672861A1 (fr) 1994-03-17 1994-03-17 Générateur de chaleur, en particulier pour la production de vapeur, du type à faible NOX, avec des chambres multiples formées par des tubes, utilisant des brûleurs radiants

Country Status (1)

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EP (1) EP0672861A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012021533A2 (fr) * 2010-08-09 2012-02-16 Naranjo Aldozkar D Herrera Dispositif de chauffage d'un liquide et de génération de vapeur
WO2011124506A3 (fr) * 2010-03-29 2013-01-31 Huseyin Atala Centrale électrique et procédé de production d'énergie électrique avec de la vapeur

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB868379A (en) * 1958-04-10 1961-05-17 Karl Hans Reppel Improvements in and relating to marine water tube boilers
US3289642A (en) * 1963-09-23 1966-12-06 Schoppe Fritz Boiler for the heating or vaporization of a liquid medium
EP0233030A2 (fr) * 1986-02-10 1987-08-19 Alzeta Corporation Chaudière de chauffage

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB868379A (en) * 1958-04-10 1961-05-17 Karl Hans Reppel Improvements in and relating to marine water tube boilers
US3289642A (en) * 1963-09-23 1966-12-06 Schoppe Fritz Boiler for the heating or vaporization of a liquid medium
EP0233030A2 (fr) * 1986-02-10 1987-08-19 Alzeta Corporation Chaudière de chauffage

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011124506A3 (fr) * 2010-03-29 2013-01-31 Huseyin Atala Centrale électrique et procédé de production d'énergie électrique avec de la vapeur
WO2012021533A2 (fr) * 2010-08-09 2012-02-16 Naranjo Aldozkar D Herrera Dispositif de chauffage d'un liquide et de génération de vapeur
WO2012021533A3 (fr) * 2010-08-09 2012-06-14 Naranjo Aldozkar D Herrera Dispositif de chauffage d'un liquide et de génération de vapeur
GB2496360A (en) * 2010-08-09 2013-05-08 Aldozkar D Herrera Naranjo Device for heating liquid and generating steam
GB2496360B (en) * 2010-08-09 2013-11-27 Aldozkar D Herrera Naranjo Device for heating liquid and generating steam
US8750695B2 (en) 2010-08-09 2014-06-10 International Green Boilers, Llc Device for heating liquid and generating steam

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