DE2228560A1 - DEVICE FOR REDUCING THE TEMPERATURE IN THE FURNACE OF A STEAM GENERATOR - Google Patents

Description

FORNEY INTERNATIONAL, INC ₁ DALLAS, TEXAS
6434 MAPLE AVENUE
V _e St. A.

Device for lowering the temperature in the furnace part

a steam generator

The invention relates to a device for reducing the temperature in the furnace part of a steam generator "

In the generation of energy from fossil fuels, there is great interest in reducing pollution in the form of nitrogen oxides that are released into the atmosphere. This problem can be better understood if one considers the basic chemical processes that lead to the formation of nitrogen oxides ^ the two criteria governing the increase in temperature and, on the other feeding are excessive amounts of oxygen to enhance the response time _o As a result, can be reduce the formation of nitrogen oxides in large steam generators; that the flue gases or other inert gases are returned to the combustion zone in the circuit, so that the temperatures

Patent attorneys Dipl.-Ing. Mqrtin Licht, Dipl.-Wirtsch.-Ing. Axel Hansmann, Dipl.-Phys. Sebastian Herrmann

and reduce the combustion time, whereby the content of nitrogen oxides in the combustion products is reduced o In addition, by mixing inert gases with combustion air, the effective percentage of oxygen in the combustion air is significantly reduced _9, which further slows down the chemical reaction ₉ that leads to the formation of nitrogen oxides will.

It has been found that simply adding large amounts of inert gas through the conventional torch throat zone creates a pressure drop that is significantly greater than the pressure drop across the torch register and throat zone under normal operating conditions. In addition, it has been found that certain inert gases tend to absorb the ultraviolet part of the light spectrum transmitted by the burner flame, which considerably impairs the operation of the ultraviolet flame detectors, which usually contribute to the safe operation of large steam generators. In addition, there _is the reduced oxygen content in the combustion air and the higher. Burner-

those when introducing inert gases

occur in conventional® Bresraerkonstruktionem, a flame with limit stability

In order to eliminate this © Nachaile au, an invention

Developed according to a B @ ppelhals- and register construction; which brings a © better flash stabilityj, lower wind and furnace pressure differences, Tbasser © Flanmensensorerbediingiiingen uKid © iae maximal® adjustment of the burner with it, wätoreiad the temperature and the amount of the burn been forehand © © m®js S®M rstoffs reduced to the Bildhmsag of nitro oxides to®rabzus © @ a tz _e Srfiadiragsgemäß it is possible at the Holasystemenj arfooiten with föas and / od © r oil, a ansaoltantssreii Brennerbetri © b

209883/0812

to achieve when the steam generator is operated so that the formation of nitrogen oxides in the flue gases is kept to a minimum. With the help of the invention proposal therefore the possibility is created to recirculate the flue gases and combine them with the combustion air to combine or to introduce the flue gases separately into the combustion zone. Furthermore, the double neck and register construction of the type according to the invention conventional burner construction currently in use can be adapted, while still being desirably high Neck velocities can be achieved while the relatively large amounts of combustion air required for nitrogen oxide reduction are required, can be processed without unduly large pressure differentials between wind boxes and furnace arise.

According to the embodiment shown in the drawing explained below, the invention features and to see advantages in the fact that an apparatus for reducing the temperature present in the furnace part of a steam generator is created, which is provided with heat-absorbing, tubular walls in which there are through openings. Burners are arranged at the passage openings, which feed a flow of the products to be burned into the furnace initiate, wherein the burners are surrounded by a housing, the essentially inert gases to the passage openings transported The apparatus or device according to the invention has a neck portion surrounding each burner and is arranged coaxially in each of the through openings so that an annular flow channel is formed, the Primary register device is movably mounted in the housing between each burner and the associated neck part. A secondary register device is movable in the housing between each neck part and the associated through opening

209883/0612

appropriate. As a result, the gas flow becomes a primary flow, which mixes directly with the combustion product troni is, and a secondary, annular, enveloping gas flow divided, which flows through the annular flow channel and is discharged over the neck part also to the To surround combustion product stream so that the temperature and oxygen content of the combustion product stream is reduced and the formation of nitrogen oxides is slowed down.

According to the invention, the formation of nitrogen oxides in the furnace section of a steam generator by creating a neck-shaped construction, which is arranged coaxially in the burner through-openings, further with two separate registers are used.

The invention is explained in more detail below with reference to the exemplary embodiment shown in the drawing. In the Drawing show:

Fig. 1 is a sectional view of the entire furnace and wind box installation of the steam generator, with the double neck and register device and upper Burner rows are shown schematically and in this Ausfülix'ungsform only a single one Source for primary and secondary air is used, and

2 shows a sectional view through the wind box and the through opening in the vicinity of the lower one left burner of the steam generator of Fig. 1, wherein, according to a further embodiment, a separate source is shown for the secondary air

A steam generator furnace part 10 is shown schematically in FIG shown, which is equipped with a double-neck double register system

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can be seen, which is designated generally by 12. The furnace part IO consists of heat-absorbing, tubular walls 14 in which there are passage openings 16 for introducing streams of combustion product into the furnace part IO. The combined double neck and register system 12 is constructed so that it is suitable for a conventional burner 18. The tubular walls 14 are covered with an outer wall 22 around the circumference. For the sake of simplicity, the collection system and other parts of the steam generator have not been shown here. A wind box housing 24 is arranged outside the furnace part 10, which surrounds the double neck system 12 and the burners 18. A line system 26 is in flow connection with the wind box housing 24 and a source of essentially inert gases, which is not shown here. The inert gas flow is indicated by the directional arrows 28, whereby it is generally assumed that it contains flue gases originating from the burner exhaust and possibly also air from the preheater, which could also be mixed with the flue gas, depending on the operating conditions of the steam generator _{or the like}

The burner 18 is shown in detail in FIG. It has a cylindrical housing 30 on which a pair of ⁿ * gas guns 32 and an oil gun 34 and an igniter disposed 36th The wind box housing 24 is formed by a housing wall 40 which delimits an inner housing 42 so that the burner 18 extends through the housing wall 40 into the inner housing 42. A tube collar 44 and an associated throttle 46 are attached to the burner housing 30 and serve to introduce part of the inert gas flow 28 directly into the burner 30.

It should be noted that the one shown in Pig «I Embodiment of the double register and neck construction 12 a single source of gas stream 28 is used during

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2278560

the embodiment according to FIG. 2 is a wind box housing 24 having two separate gas flow sources. The sub, differentiate between the one embodiment and the wind box housing 2 are explained in more detail, but it should be noted here that the schematic representation of the double register and neck construction 12 of FIG. 2 with that shown in detail in FIG Construction is the same, and that the same reference numerals are used to designate the same parts in Figs will"

As is apparent from FIG _o 1, the Doppelregister- Construct and 12 a neck portion 50 which each burner 18 surrounds and is coaxially disposed in each through hole 15 to form an annular passageway 52nd A primary register 54 is movably mounted in the wind box housing 24 between the burner 18 and the neck part 50, while a secondary register 56 is movably mounted in the wind box housing 24 between the neck part 50 and the through openings iö. Accordingly, the gas stream 28 is divided into a primary stream, which is indicated by the arrows 57 and is mixed directly with the combustion products 20, and a secondary, annular gas envelope stream, which is indicated by the arrows and flows through the annular flow channel 52 and beyond the neck portion 50 is discharged to surround the products of combustion 20. In this way, the temperature and the oxygen content of the combustion products 20 are reduced and the formation of nitrogen oxides is slowed down.

As can be seen from Fig. 2, the heat-absorbing walls 14 are formed by a conventional finned tube wall construction, and the through openings 16 are formed by bending the finned tube wall 60 _o An annular insulating collar 62 delimits an Ifalszone, which

20 9883 / ÜB 12

2278560

is generally designated by ' 6k _o The outer wall 22 comprises insulating material 66 and an outer, skin-like metal housing 68 which extends in the same direction as the finned tube wall 6ü.

The neck part 60 has a neck ring 70, which is made in one piece with a frustoconical collar 72, and an annular shoulder 74 which is arranged coaxially in the neck zone 6k with the aid of a mounting plate 76. As a result, the annular shoulder 7k is welded to the mounting plate 76, which in turn is attached to the outer housing 68 with the aid of the secondary register. This is done by attaching an annular support plate 80 having an L-shaped cross-section to the outer housing 68 and placing the annular plate 76 in a position where it is separated from the plate 80 at a distance. The secondary register 56, which has a series of wings 82 supported between the plates 76 and 80, can in fact serve as a means of supporting the plate 76, but it is also possible to use separate supports relative to the plate 76 are arranged horizontally and have not been shown in the drawing. The blades 82 are of conventional construction and are guided by shafts Qk which, in turn, are operatively connected, as usual, to a conventional linkage arrangement by which the blades 82 can be moved from various positions from an open to a closed position so that the gas flow can be controlled through the annular space 52 through ₀

A retaining ring 86 is welded to the plate 76 and serves to support an annular arm 88 which holds the primary register 5h. This is done by attaching an outer plate 90 to the horn housing 30 in a position in which it is separated from the arm 88 at a distance

709RR3 / OK1?

'2278560

is. As a result, the primary register 54 associated with a row Ilaupflügel 52 is provided between the arm 88 and the outer Plate 90 out. As in the case of the secondary register, 56 will be also the main wings 92 are movably supported around the circumference of the primary register 54 by means of a series of shafts 94 which are also provided with a conventional linkage system, which is not shown in the drawing and is used to the main wing 92 between an open and a closed Position to operate. A heat shield 96 is attached to the outer plate 90 by supports.

As can be seen, the embodiment shown in FIG. 2 differs from that shown in FIG. 1 in that the housing wall 40 in FIG. 2 is mounted on an auxiliary wind box instead of the outer wall 22 as in FIG. Thus, as shown schematically in FIG. 2, the auxiliary windbox 100 has a housing wall 102 which is fastened to the housing 68 in order to enclose the secondary register 56. In this way, the line system 26 conveys the inert gas stream 28 to the inner housing 42 of the wind box 40, while a secondary inert gas stream, which is indicated by the directional arrows 104, is conveyed into the auxiliary wind box 100. Accordingly, the inert gas § · stream 28 supplied in the embodiment of FIG _o 1, both the primary register 54 and the Sekundärregxster 56j, while in the disclosed embodiment of FIG _o 2 of the inert gas stream 28 through the primary register 54 and the secondary inert gas flow 104 through the Sekundärregxster 56 flow. Thus, in the embodiment according to FIG. 2, the annular gas flow envelope 58 is formed by the secondary inert gas flow 104, while the inert gas flow 28 forms the primary flow 57.

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Claims (3)

'2278560 PATENT CLAIMS 1, 'Device for lowering the temperature in the furnace part of a steam generator, which is provided with heat-absorbing, tubular walls in which there are passage openings are located, characterized in that at the passage openings (16) burners (18) for introducing a combustion product flow are arranged in the furnace (10) that the burners (18) are surrounded by a housing (42), with which essentially inert gases can be conveyed to the through-openings (16), that each burner has a neck part (50) is surrounded coaxially in each through hole (16) is arranged around an annular flow channel (52) to form that in the housing (42) between each Burner (18) and the associated neck part (50) a primary register (54t) is movably mounted, and that in the housing (42) also a secondary register (56) movable between each Ilalteil (50) and the associated passage opening (16) is stored, through which the gas stream in a primary stream (28j 57) »which mixes directly with the combustion product stream is, and a secondary, annular gas envelope flow (58, 104) is available, which through the annular The flow channel (52) can be guided through and through the neck part (50) is drivable to surround the combustion product stream so that the temperature and oxygen content of the combustion product flow can be reduced and the formation of nitrogen oxides can be inhibited. 2. Device according to claim 1, characterized in that the gas flow through the housing (42) into the primary register (54) and the secondary register (56) can be funded. 209883 / ßf51? - OK ~ 3. Apparatus according to claim 1, characterized in that the housing (42) has a secondary wind box (100) which is attached to the furnace (10) and is in flow connection with the secondary register (56), and a main wind box (2h) , which is stored on the secondary wind box (100) and is in flow connection with the primary register (5 ^). ^l i. Device according to Claim 1 _s, characterized in that the neck part (50) has a neck ring (70) which forms an inseparable whole with a frustoconical collar (72) each burner (IS) and the associated collar (72) are movably mounted, and that the secondary register (56) has a number of wings (82) which are movably mounted between the outer surface of the walls (76) and the collar (72) " 2 0 B 8 R 3 / G 6 1 2