EP0405087B1 - Dampfkessel zur Verbrennung fossiler Brennstoffe unter reduzierter Bildung von Stickoxiden - Google Patents

Dampfkessel zur Verbrennung fossiler Brennstoffe unter reduzierter Bildung von Stickoxiden Download PDF

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Publication number
EP0405087B1
EP0405087B1 EP90107819A EP90107819A EP0405087B1 EP 0405087 B1 EP0405087 B1 EP 0405087B1 EP 90107819 A EP90107819 A EP 90107819A EP 90107819 A EP90107819 A EP 90107819A EP 0405087 B1 EP0405087 B1 EP 0405087B1
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EP
European Patent Office
Prior art keywords
burner
boiler according
combustion chamber
pipe band
wall
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.)
Expired - Lifetime
Application number
EP90107819A
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German (de)
English (en)
French (fr)
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EP0405087A1 (de
Inventor
Hans Breucker
Walter Kessel
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.)
Deutsche Babcock Werke Energie und Umwelttechnik AG
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Deutsche Babcock Werke Energie und Umwelttechnik AG
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Publication date
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Publication of EP0405087A1 publication Critical patent/EP0405087A1/de
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    • 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 or dispositions of combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/40—Arrangements of partition walls in flues of steam boilers, e.g. built-up from baffles

Definitions

  • the invention relates to a steam boiler according to the preamble of claim 1.
  • the nitrogen oxides (NO x ) generated during the combustion of fossil fuels are harmful to health. Your emissions should therefore be reduced as much as possible.
  • the temperature profile in the combustion chamber is reduced by reducing the NO x , in particular the thermal NO x , by influencing the combustion process by gradually supplying fuel and / or flue gas in the main combustion zone smoothed.
  • central walls are known in a closed and open design. They divide up a combustion chamber and primarily serve to reduce the boiler height.
  • the size of the heating surface is determined by the boiler width and is therefore not very adaptable for targeted temperature reduction.
  • the temperature is evenly reduced in the vertical direction by means of central walls, although a temperature reduction is only sensible in the area of the maximum temperature.
  • DE-A-2 527 482 describes the installation of partition elements in the combustion chamber as a temperature-reducing measure for NO x reduction.
  • narrow strips of wall which are located between two adjacent rows of burners, protrude from the surrounding wall into the combustion chamber. Wall strips of this type are exposed to the flow of flue gas during operation and require a high degree of stiffening because of the possibility of fastening on one side only. Since in normal operation of a combustion system with low-NO x burners, the temperature profile of the flue gas in the horizontal direction also has a maximum in the middle and falls towards the surrounding walls, such narrow wall strips reinforce the difference between the maximum and minimum flue gas temperatures. It cannot effectively reduce the NO x emission.
  • a steam boiler is known from DE-A-2 021 815, the combustion chamber of which is divided in the central plane by a side wall that is not supported.
  • the intermediate wall extends over the entire height of the combustion chamber and has pressure equalization openings of small diameter above the upper burner level.
  • the intermediate wall of the known boiler serves to reduce the construction volume with the same boiler output.
  • the object of the invention is to design the steam boiler according to the preamble of claim 1 such that the formation of NO x in the combustion chamber is effectively reduced by the installation of an intermediate wall. This object is achieved by the features of the characterizing part of patent claim 1.
  • the intermediate wall in the form of a tubular band which extends in a vertical central plane between the burner wall and the rear wall and is arranged between the lower burner level and a distance from the burner level above the upper burner level. causes a targeted lowering of the flue gas temperature in the area of the maximum temperature in the middle of the combustion chamber. There is only a very slight drop in temperature in the areas of low flue gas temperature, such as in the vicinity of the combustion chamber walls, the combustion chamber floor, and above the burner levels. This effectively reduces the formation of NO x . This is especially true for the formation of thermal NO x , the formation rate of which increases disproportionately with temperature at higher temperatures.
  • the horizontal passages ensure complete pressure and temperature compensation, which is required for trouble-free and effective operation of the furnace.
  • the furnace band can be used as the only NO x -measuring measure or in addition to the known measures (eg OFA, IFNR). It is particularly advantageous in old systems that, for reasons of heat balance, the additional heating surfaces in the combustion chamber make it possible to recirculate flue gas or to increase the amount of recirculated flue gas already present.
  • the feature of claim 2 is particularly advantageous for boilers that are already provided with a flue gas recirculation.
  • the construction of a second, parallel flue gas recirculation can be carried out while the plant is in operation.
  • the shape and arrangement of the tubular band described in claim 3 maintains the flame structure and thus the mutual support effect of the individual flames with one another in the horizontal direction, which is particularly important when igniting the burners.
  • Another advantage of the feature of claim 3 is that the flames of the burners arranged next to the tube band spread essentially in the free areas, the passages, of the zigzag band. This prevents the tubes from coming into direct contact with the flame.
  • the routing of the discharge pipes through one of the combustion chamber walls in the upper half of the combustion chamber according to claim 5 enables the arrangement of the pipe band in the main combustion zone in a simple form. It is particularly convenient to run the discharge pipes by a half to one burner level spacing above the top burner levels because i.a. From this height, the temperatures in the combustion chamber drop again (see Fig. 9).
  • the feature of claim 6 is particularly suitable for forced circulation and once-through boilers, for example Benson boilers. It enables easy connection of the pipe belt to an existing boiler.
  • the feature of claim 7 is also particularly suitable for forced circulation and once-through boilers.
  • claims 8 and 9 are particularly suitable for natural circulation boilers.
  • An advantage of the feature of claim 10 is that the tips of the tubular band can be easily attached to the firebox walls at their central sections. Another advantage is that the distances between the pipe bends prevent expansion stresses.
  • An advantage of the feature of claim 11 is that the middle sections can be easily manufactured.
  • the arrangement of the tubes in the central region of the tips on the combustion chamber wall is advantageous because additional heating surfaces and thus an additional temperature reduction in the vicinity of the combustion chamber walls are avoided (cf. FIG. 10).
  • the feature of claim 13 describes an advantageous embodiment and attachment of the band for a steam boiler with four burner levels and that of claim 14 for a steam boiler with three burner levels.
  • FIG. 1 shows a schematic representation of a Benson boiler (example 1) with a subsequently installed, welded tubular band.
  • Figure 2 is a corresponding plan view from above of the firebox of the boiler and in Figure 3 is an enlarged section with implementation of the Drainage pipes of the pipe band can be seen through a combustion chamber wall.
  • Figure 4 A circuit diagram of Example 1 is shown in Figure 4.
  • FIGS. 5 to 8 show two exemplary embodiments of tips of the tubular band, front plan views in FIGS. 5 and 7 and corresponding cross sections in FIGS. 6 and 8.
  • FIGS. 9 and 10 show the temperature profiles of the flue gas as a function of the boiler height (FIG. 9) and the boiler width (FIG. 10) without a pipe band (dashed line) and with a pipe band (solid line).
  • FIG. 11 shows a schematic illustration of a natural circulation boiler (example 2) with a built-in tube band
  • FIG. 12 shows a corresponding top view of the combustion chamber
  • FIG. 13 shows a corresponding circuit diagram.
  • Each of the four burner levels 2 to 5 is equipped with four horizontally aligned burners 10 with flue gas recirculation 11.
  • the four burners 10 of one level are arranged side by side on a burner wall 12.
  • the burner wall 12 and an opposite rear wall 13 form the longer sides in the rectangular cross section of the combustion chamber 1.
  • the air openings 7 are located on both side walls 14, 15 of the combustion chamber 1 perpendicular to the burner wall 12, three air openings 7 being arranged next to one another.
  • a tube band 16 made of tubes 17 welded to one another.
  • the tube band 16 is in a region which is between the first and second burner levels 2, 3 begins and ends between fourth burner level 5 and air openings 7, is arranged and extends in a vertical direction in a zigzag shape between rear wall 13 and burner wall 12.
  • the shape of the tubular band 16 resembles two superimposed Vs rotated through 90 ° in the clockwise direction, the tips of which are flattened.
  • the level of Burner levels 3, 4, 5 between the straight sections of the tube band 16 have free, horizontal passages, corresponding to the shape of the tube band 16, the shape of triangles with flattened tips, ie trapezoids.
  • the areas of the combustion chamber 1 in the vicinity of the combustion chamber walls 12, 13, 14, 15 are free of heating surfaces.
  • the firebox 1 between the firebox floor 6 and the first burner level 2 is free of heating surfaces.
  • a supply pipe 21 opens into each pipe 17 of the pipe band 16.
  • the supply pipes branch off from a lower header 23 and are guided alternately around a pulling band 24 attached to the center of the rear wall 13 through the rear wall 13.
  • Each pipe 17 also has a discharge pipe 22.
  • the discharge pipes 22 are routed in the same way as the supply pipes 21, alternating left and right around the drawstring 24 to an upper collector 25.
  • a second flue gas duct 26 is connected to the firebox ceiling 8 and the wall superheater 9 on the rear wall 13 side.
  • a flue gas duct 27 branches off from the second flue gas duct 26 near the ground and leads, for example, to a flue gas cleaning system via an air preheater.
  • Two flue gas lines 28, 29 branch off from this flue gas duct 27, the second of which was subsequently installed together with the pipe band 16.
  • the flue gas lines 28, 29 are each provided with a blower 30, 31.
  • the flue gas line 28 is connected to the flue gas return lines 11 of the burners 10 and the flue gas line 29 to the secondary air of the burners 10.
  • An economizer 32 is arranged in the lower part of the second flue gas duct 26, approximately at the level of the second burner level 3.
  • a pipeline leading from the economizer 32 to an evaporator 33 before the installation of the tube band 16 is interrupted at a height above the lower header 23; its pipe section 34 leading away from the economizer 32 is connected to the lower collector 23 via a feed line 35 and its pipe section 36 leading to the evaporator 33 is connected to the upper collector 25 of the pipe band 16 via a discharge pipe 37.
  • the tube band 16 is connected between the economizer 32 and the evaporator 33.
  • steam coolers 38 and superheaters 39 are arranged behind the evaporator 33 and wall superheater 9 (FIG. 4).
  • the economizer 32 is connected to a feed pump 41 by a feed line 40.
  • An injection water line 42 branches off from line 40 and leads to the steam coolers 38.
  • the tube band 16 is formed from fifty directly welded tubes 17, only a few being shown in the drawing (FIGS. 5 and 6).
  • the tubes 17 consist of heat-resistant or high-temperature steel and have, for example, an outer diameter of 57 mm and a wall thickness of 5.6 mm.
  • the entire width of the tube band 16 is approximately 3 m. In the area in which the tube band 16 is arranged, it covers approximately 40% of the central area, and accordingly approximately 60% of the area remains free through the passages. As a result, the tube band 16 forms approximately 20% of the heating surface of the combustion chamber 1 in this area.
  • the flattened tips 18, 19, 20 each consist of three sections, a middle section 43 and two outer sections 44.
  • the tubes 17 are arranged straight, vertically next to one another in the middle section 43 and welded to one another via (about 10 mm wide) webs 45.
  • the tubes 17 In the outer sections 44 adjoining it at the top and bottom, the tubes 17 have tube bends 46 which run at a distance from one another.
  • the tubular band 16 In the lower outer section 47 of the middle tip 19, the tubular band 16 has a fold.
  • the positions of the tubes 17 are exchanged so that the outer tube 48 in the lower "V" lies in the upper "V” inside.
  • the tubes 17 are all of the same length due to the folding.
  • FIGS. 5 to 8 show an exemplary embodiment for fastening the tube band 16 by means of full welding to the tube webs of the natural circulation boiler; the fastening described above with holding irons is not shown.
  • the influence of the tube band 16 on the temperature profile of the flue gas in the combustion chamber 1 was calculated and represented using a furnace zone model as a function of the boiler height (FIG. 9) and as a function of the boiler width (FIG. 10).
  • the temperature profile of the flue gas after installation of the tube band 16 shows a significant reduction in the temperature in the maximum compared to the temperature profile before installation of the tube band 16 (dashed line).
  • the lowering of the flue gas temperatures in the combustion chamber is achieved on the one hand by the additional heating surface of the pipe belt and on the other hand by doubling the amount of flue gas returned.
  • This increase in the quantity of flue gas returned to the combustion chamber 1 also serves to regulate the heat balance of the boiler, which is changed by an enlarged heating surface.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
EP90107819A 1989-06-28 1990-04-25 Dampfkessel zur Verbrennung fossiler Brennstoffe unter reduzierter Bildung von Stickoxiden Expired - Lifetime EP0405087B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3921076 1989-06-28
DE3921076A DE3921076C1 (enrdf_load_stackoverflow) 1989-06-28 1989-06-28

Publications (2)

Publication Number Publication Date
EP0405087A1 EP0405087A1 (de) 1991-01-02
EP0405087B1 true EP0405087B1 (de) 1993-05-26

Family

ID=6383709

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Application Number Title Priority Date Filing Date
EP90107819A Expired - Lifetime EP0405087B1 (de) 1989-06-28 1990-04-25 Dampfkessel zur Verbrennung fossiler Brennstoffe unter reduzierter Bildung von Stickoxiden

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EP (1) EP0405087B1 (enrdf_load_stackoverflow)
DE (2) DE3921076C1 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101836124B1 (ko) * 2016-03-25 2018-04-19 김동희 다단 연소기능을 갖는 소형증기보일러 및 이를 이용한 소형 열병합발전시스템

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1256224B (de) * 1965-04-07 1967-12-14 Steinmueller Gmbh L & C Aus Rohren gebildete Feuerraumzwischenwand
DE2021815A1 (de) * 1970-05-05 1971-11-25 Ver Kesselwerke Ag Schwingungssteife,vollverschweisste Stegrohr-Profilwand fuer Zwischenwaende in Feuerraeumen mit grosser Kesselleistung
DE2539546C3 (de) * 1975-09-05 1985-10-24 Metallgesellschaft Ag, 6000 Frankfurt Verfahren zur Verbrennung kohlenstoffhaltiger Materialien

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101836124B1 (ko) * 2016-03-25 2018-04-19 김동희 다단 연소기능을 갖는 소형증기보일러 및 이를 이용한 소형 열병합발전시스템

Also Published As

Publication number Publication date
DE59001540D1 (de) 1993-07-01
DE3921076C1 (enrdf_load_stackoverflow) 1991-02-07
EP0405087A1 (de) 1991-01-02

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