EP1991810A1 - Round burner - Google Patents

Abstract

Round burner for burning fossil fuels, comprising the following: a first nozzle (2) for introducing a stream of air or recirculated flue gas or a mixed stream of O2 or air and recirculated flue gas, a fuel nozzle (3) for injecting fuel, arranged coaxially in relation to the first nozzle (2), enclosing the latter and forming an annular cross section (11), a gas nozzle I (4) for introducing a stream of air or recirculated flue gas or a mixed stream of O2 or air and recirculated flue gas, arranged coaxially in relation to the first nozzle (2), enclosing the fuel nozzle (3) and forming an annular cross section (12), a gas nozzle II (5) for introducing a stream of air or O2 or a mixed stream of O2 or air and recirculated flue gas, arranged coaxially in relation to the first nozzle (2), enclosing the gas nozzle I (4) and forming an annular cross section (13), a gas nozzle III (6) for introducing a stream of air or recirculated flue gas or a mixed stream of O2 or air and recirculated flue gas, arranged coaxially in relation to the first nozzle (2), enclosing the gas nozzle II (5) and forming an annular cross section (14), wherein, in the gas nozzle outlet region (17), the surface area of the annular cross section (13) of the gas nozzle II (5) is in a ratio of 1.2 to 2.0:1 to the surface area of the annular cross section (12) of the gas nozzle I (4) and the surface area of the annular cross section (14) of the gas nozzle III (6) is in a ratio of 0.2 to 0.8:1 to the surface area of the annular cross section (12) of the gas nozzle I (4) and the surface area of the cross section (10) of the first nozzle (2) is in a ratio of 0.01 to 0.1:1 to the surface area of the annular cross section (12) of the gas nozzle I (4).

Description

circular burner

The invention relates to a round burner for the combustion of fossil fuels and a method for operating such a round burner.

Round burners are next jet burners, which are usually rectangular cross-sections, the most commonly used burners in combustion chambers of large power plants, where fossil fuels is burned. They are often also referred to as vortex or swirl burner, since usually the introduced oxidizing agent and / or the introduced fuel is twisted or swirled by means of swirling devices, in order to carry out the combustion more efficiently. Such round burners, which have become known for example from document "Development of low-emission dust combustion systems" from VGB power plant technology 76 (1996), Issue 5, usually have a core air tube (or Kemluftdüse) on the outside of a fuel pipe (or nozzle The secondary air tube may be surrounded by a tertiary air tube (or nozzle) on the outside, whereby all tubes or nozzles are aligned coaxially and thus each have circular ring cross sections Through the respective tubes or nozzles, the medium named according to the name of the pipe or nozzle is introduced into the combustion chamber for combustion of the fossil fuel, eg secondary air is introduced through the secondary air nozzle Fuel is entered through the fuel nozzle along with its carrier medium, the primary air protrude.

Since combustion of fossil fuels by means of air as an oxidant is known to emit CO ₂ -containing flue gas into the atmosphere and the CO ₂ as a suspected major cause of the climate-changing greenhouse effect increasingly comes under public scrutiny, the oxyfuel process has already been proposed is used for combustion instead of air pure oxygen as the oxidant. By using pure oxygen or O ₂ recovered from the air, a CO ₂ stream can be used instead of the emission of flue gases be provided of high purity, which can be deposited and deposited klimaunwirksam. Such an oxyfuel process or such Oxyfuel combustion process has become known, for example, by document DE 103 56 703 AI.

For the power plant or burner suppliers and operators results from the aforementioned the fact that on the one hand with respect to the different fossil fuels used round burner cross sections due to different Oxidationsmittelbedarfes result and the other with respect to the oxidant used, ie either air or O ₂ , again different and differing round burner cross-sections as well as deviating in the nature of the gas gas flows result, for example, instead of an air flow in conventional operation a Rezigasstrom (recirculated flue gas) in oxyfuel operation. Is the power plant or burner supplier in the design of a round burner thus on a fossil fuel and an oxidant fixed, the power plant operator remains at a later change of fuel or a change from air to pure oxygen as the oxidant, otherwise As the or the round burner (a combustion chamber of a power plant usually has a variety of such round burners on) to rebuild the new situation or the new fuel out. Such a required conversion is very disadvantageous from a variety of perspectives, because the entire power plant must be taken out of service because of the conversion and in this phase a high revenue loss, for example by elimination of electricity generation, is recorded. Furthermore, considerable material and assembly costs for the new round burners are due.

The object of the invention is therefore to provide a round burner, which is able, if necessary, different fossil fuels, such as

- dry lignite with air or

- dry lignite with a GyTräger, wherein different O ₂ -Volumenanteile may be present, or

- coal with air or - Coal with an O ₂ carrier, wherein different O ₂ -volume shares may be present, or

- oil / gas with air or

- Oil / gas with an O ₂ carrier, whereby different OyVolumenanteile may be present, to burn and thereby has a large control range. Furthermore, the outlet velocities of the various gas streams or of the fuel stream must not exceed or fall below certain speed ranges on the round burner which is to be newly created, since otherwise a stable ignition of the introduced fossil fuel is no longer guaranteed or the blowers required for the various gas streams become uneconomically large are to be dimensioned. It is a further object of the present invention to provide a method for operating such a round burner.

The above object is achieved with respect to the round burner by the features of claim 1 or 2 and in terms of the method for operating a round burner by the features of claim 11.

Advantageous embodiments of the invention can be found in the dependent claims.

The inventive solution is a round burner and a method for

Operating a round burner created which has the following advantages:

Great flexibility in the amount of O ₂ carrier flow, thus

- degrees of freedom in the choice of fuel,

- Degrees of freedom in the choice of the O ₂ content of the GyTrägerstroms, possibly even in the individual cross-sections of the various gas nozzles,

Possibility of adding the oxygen required for combustion directly to the burner,

- large control range. In an advantageous embodiment of the invention, one of the gas nozzles I, II or III or gas nozzles II.1 are formed in their entirety such that by their cross section in oxyfuel operation, the total amount of oxygen over this one cross section or in the case of the gas nozzle II.1 on their Entire cross-section is introduced, which is required for the combustion of the fuel introduced at the round burner.

In order to achieve a safe and stable ignition of the fossil fuel, it is advantageous, the first nozzle and / or the fuel nozzle and / or the gas nozzle I and / or the gas nozzle II or gas nozzles 11.1 and / or gas nozzle III with a storage ring and / or to train with a deflector throat.

In an advantageous embodiment of the invention, the first nozzle and / or the fuel nozzle and / or the gas nozzle 1 and / or the gas nozzle II or gas nozzles 11.1 and / or the gas nozzle III spin elements. By this measure, the combustion of the fossil fuel can be intensified and optimized. It is expedient to twist the swirl elements of the first nozzle and the fuel nozzle either in the same direction or in opposite directions to each other, i. to adjust the swirl elements such that either an equal or an opposing swirl arises at the gas and fuel stream passed through.

An expedient embodiment of the invention provides that the swirl elements can be adjusted during burner operation at the gas nozzle I and / or gas nozzle II or at the gas nozzles II.1 and / or gas nozzle III. This can be acted on at any time during the power plant operation on the firing.

An expedient embodiment of the invention provides that the width s of the annular gap of the fuel nozzle annular cross section is at least 20 mm. By this measure, the pressure loss caused by the fuel nozzle can be kept low and the geometries of the other nozzles of the round burner can be favorably influenced. A further advantageous embodiment provides that the longitudinal axes of the gas nozzles II.1 are arranged parallel or inclined to the longitudinal axis of the first nozzle or to the round burner.

Embodiments of the invention with reference to the drawings and the description are explained in more detail.

It shows:

1 shows schematically a longitudinal section through a round burner according to the invention,

2 schematically shows a cross section according to section A-A in Figure 1,

3 as Figure 1, but alternative embodiment,

FIG. 4 schematically shows a cross section according to section B-B in FIG. 3, FIG.

5 as Figure 4, but alternative embodiment,

6 shows the assignment or connection of the respective round burner nozzle cross sections during operation as a function of the O ₂ carrier volume flow and the gas velocity by means of a diagram.

Figure 1 shows a round burner 1 according to the invention in longitudinal section, which is suitable for the combustion of various fossil fuels. The round burner 1 is designed so that, depending on requirements, for example, powdered dry lignite or powdered coal or oil or gas (for the use of the round burner according to the invention for the combustion of oil or gas is still an oil or gas lance, not shown, for introducing the fuel , the Centric in the round burner is arranged) can be burned either by means of air or by means of O ₂ , which is introduced by an O ₂ carrier. The O ₂ carrier may have different O ₂ volume proportions, the O ₂ carrier is usually a recirculated from the rear flues of the power plant flue gas or Rezigas. Thus, the round burner 1 according to the invention is not only suitable for the combustion of different fuels, but also for the use of different oxidants, ie it can be added in the conventional manner, air or O ₂ , ie pure oxygen, in oxyfuel operation to thereby form high-purity CO ₂ , which is separable and climate-depended landfillable. The oxygen is, as already mentioned above, supplied as a mixture with, for example Rezigas, wherein the proportion of oxygen in the mixture may vary.

The used as O ₂ carrier gas recirculated flue gas (Rezigas) is taken for example from the combustion chamber downstream flue gas path and fed to the round burner 1 at a temperature of 150 ° to 300 ° C. For this purpose, if necessary, it must be reheated by heat exchange with a hotter medium. The Rezigas can have a low residual oxygen content.

According to FIGS. 1 and 2, the round burner 1 according to the invention comprises a first nozzle 2 having a cross-section 10, which is surrounded or enveloped by a fuel nozzle 3 aligned coaxially with the first nozzle 2, and a circular ring cross-section 11 is formed between the first nozzle 2 and the fuel nozzle 3 is, whose annular gap in the radial direction has a width s. The fuel nozzle 3 is surrounded or surrounded by the gas nozzle I 4, this of the gas nozzle Il 5 and the latter of the gas nozzle III 6. The gas nozzles I, II and III 4, 5 and 6 are all aligned coaxially with the first nozzle 2, wherein within the gas nozzles I, II and III 4, 5 and 6, the circular ring sections 12, 13 and 14 are formed. On the gas flow side seen outlet end of the gas nozzle III ό joins the burner throat 18, which forms the transition to the combustion chamber, not shown.

Figure 3 and 4 shows a further round burner 1 according to the invention. In contrast to the round burner according to Figures 1 and 2, this has no coaxial On the other hand, eight gas nozzles II.1 5.1, whose longitudinal axes 16 are parallel to the longitudinal axis 15 of the first nozzle 2 and the round burner 1 and the gas nozzles II.1 5.1 within the circular ring cross section 12 of the gas nozzle I 4 are arranged. Instead of the parallel alignment of the longitudinal axes 16 to the longitudinal axis 15, the longitudinal axes 16 of the gas nozzles II.1 5.1 can also be inclined, ie aligned at an angle to the longitudinal axis 15 of the first nozzle 2 (not shown). The gas nozzles 11.1 5.1 can either be directed towards the longitudinal axis 15 or away from it. Alternatively, and as shown in FIG. 5, the gas nozzles 11.1 5.1 can also be arranged inside the circular ring cross-section 14 of the gas nozzle III6. The gas nozzles 11.1 5.1 have in total an overall cross section 13.1. The centers of all gas nozzles II.1 5.1 lie advantageously on a pitch circle and are preferably equally spaced from each other.

According to the invention, the cross sections 10, 12, 13 or 13.1 and 14 of the first nozzle 2 and the gas nozzles I, II or II.1 and III 4, 5 or 5.1 and 6 in the gas nozzle exit region 17 in certain relations to one another. In detail, the surface of the circular ring cross section 13 of the gas nozzle Il 5 in the ratio of 1, 2-2.0: 1 to the surface of the circular ring cross section 12 of the gas nozzle I 4 and the surface of the circular ring cross section 14 of the gas nozzle III 6 in the ratio of 0.2 -0.8: 1 to the surface of the annulus cross section 12 of the gas nozzle I 4 and the area of the cross section 10 of the first nozzle 2 in the ratio of 0.01-0.1: 1 to the surface of the annulus cross section 12 of the gas nozzle I 4. Reference the different cross-sectional areas of the nozzles 2, A ₁ 5 or 5.1 and 6, it is possible that the round burner 1 with respect to the supply of the necessary oxidizing agent for combustion receives maximum flexibility, ie by the different sized cross-sectional areas 10, 12, 13 and By suitable combination of the nozzles 2, 4, 5 or 5.1 and 6 or their cross sections 10, 12, 13 or 13.1 and 14, 13.1 and 14 can be used for different bre offered by the company. All cross sections 10, 1 1, 12, 13 or 13.1 and 14 are designed so that the minimum required or maximum allowable flow velocities of the gas or fuel passed through are maintained within the respective cross sections. The Gαsgeschwindigkeiten in the nozzles 2, A ₁ 5 or 5.1 and 6 are between 15 and 80 m / s.

The gas nozzle exit region 17 defines the region in which, seen over a respective cross section, all cross sections 10, 11, 12, 13 or 13.1, 14 of the nozzles 2, 3, A ₁ 5 and 5.1, 6 exist and the various partial gas streams and the fuel flow last in the respective nozzles 2, 3, A ₁ 5 and 5.1, 6 flow through before they exit into the combustion chamber.

The circular ring cross-section 1 1 of the fuel nozzle 3 is dependent on the carrier medium volume flow carrying the fuel and on the speed of the carrier medium within the fuel nozzle 3, which is generally 10 to 35 m / s. Thus, on the one hand the pressure losses caused by the fuel nozzle 3 in a conventional frame or low and on the other hand, the geometries of the remaining nozzles 2, A ₁ 5 or 5.1 and 6, in particular the first nozzle 2 also in a realistic and practical size remain, the width s of the annular gap of the circular ring section 1 1 of the fuel nozzle 3 in the radial direction is advantageously formed with at least 20 mm.

FIG. 6 shows a diagram from which it can be seen by way of example which nozzle combinations are possible as a function of the O ₂ carrier volume flow introduced by the round burner 1. 0 to about 20% of the O ₂ carrier volume flow are introduced only by the cross section 13 or 13.1 of the gas nozzle Il 5 and the gas nozzles II.1 5.1. As the O ₂ carrier volume flow increases, it is introduced through the gas nozzle I 4 instead of through the gas nozzle (s) Il 5 or II.1 5.1. If the O ₂ carrier volume flow increases further, the cross section 13 or 13.1 of the gas nozzle (s) Il 5 or 11.1 5.1 is added to the gas nozzle I 4. With further increasing O ₂ - carrier volume flow is on the cross sections 13 and 13.1 and 14 of the gas nozzles Il 5 and II.1 5.1 and III 6, then on the cross sections 12 and 14 of the gas nozzles I 4 and III 6 and last but not least all available cross sections 12, 13 or 13.1 and 14 of the gas nozzles I, II or II.1 and III A ₁ 5 or 5.1 and 6 transferred to the entry of the respective gas streams. With the latter combination, the maximum O ₂ - Carrier volume flow through the round burner 1 are introduced. In cases where one or two of the gas nozzles has no flow rate of an O ₂ carrier volume flow, this gas nozzle or these gas nozzles can be acted upon with a small amount of gas for cooling purposes. This is especially true when the outer gas nozzle III 6 has no O ₂ carrier volume flow rate.

For an oxyfuel operation of the round burner 1 may be formed such that one of the cross-sectional surfaces 12, 13 or 13.1 or 14 of the gas nozzles I, II or II.1 or III 4, 5 or 5.1 or 6 is suitable, the entire required Oxygen quantity through this introduce a cross-section, while the required amount of oxygen as a pure O ₂ gas stream can be introduced. In order to reduce peak temperatures in the combustion chamber, at least one further gas nozzle I, II or 11.1, III 4, 5 or 5.1, 6 must be supplied with Rezigas.

When using the round burner 1 according to the invention for the combustion of a fossil fuel, for example dry lignite, hard coal, oil or gas in oxyfuel operation, ie the oxidizing agent for combustion is pure oxygen, the introduction to the burner 1, for example, look like the following: introduction of the fossil fuel through the fuel nozzle 3, introduction of O ₂ through the gas nozzle Il 5 or gas nozzles II.1 5.1 and introduction of Rezigas, ie of recirculated flue gas through the first nozzle 2 and as a carrier gas through the fuel nozzle 3 and through the gas nozzles I and III 4, 6 Alternatively, the Rezigasströmen within the first nozzle 2, the fuel nozzle 3 and the gas nozzles I and III 4, 6 an oxygen flow component and the O ₂ flow within the gas nozzle Il 5 and the gas nozzles II.1 5.1 a Rezigasstromanteil be allocated. The exemplary data relate to 100% gas flow rate through the round burner 1, at lower flow rates, as described above, the throughput through individual gas nozzles omitted (see Figure 6). If necessary, however, a small amount of cooling gas can be passed through.

In the conventional operation of the round burner 1, ie when burning fossil fuels with air as an oxidant, for example, at 100% Gαsvolumenstrom Durchsαtz, ie at VoI I last- operation of the furnace, air through all nozzles 2, 3, 4, 5 or 5.1 and 6 are introduced. In the fuel nozzle 3, the air then serves as a carrier medium for the fuel. Alternatively, the air can also be added to the respective nozzles 2, 4, 5 or 5.1 and 6 recirculated flue gas (Rezigas). At lower gas flow rates, ie at partial load operation of the furnace, as mentioned above, individual gas nozzles can be shut off by flaps and thus the flow rate can be regulated or set to virtually zero to a very low cooling medium throughput.

In order to stabilize the flame on the round burner 1 or to lead them can be used in a well-proven way Staurese 7 and / or Abweiskhlen 8. These may each be attached to each of the nozzles 2, 3, 4, 5 or 5.1 and 6 respectively. Furthermore, individual or all gas partial flows or the fuel flow can be twisted by swirl elements 9 arranged in the respective nozzle cross sections 10, 11, 12, 13 or 13.1 and 14, the gas flow in the first gas nozzle 2 and the fuel nozzle 3 (as carrier flow ) can be twisted in the same direction or in opposite directions to each other. The swirl elements 9 on the gas nozzles I, II or II.1 or III 4, 5 or 5.1 or 6 can also be designed to be adjustable during burner operation in order to influence the firing during operation. The selection of said devices depends on the preferred operating conditions (eg full-load air operation or operation with a certain Gy component, etc.) and the associated combinations of the burner cross-sections of the round burner 1. Thus, the flame guidance can be favorably influenced in these operating cases.

LIST OF REFERENCE NUMBERS

1 round burner

2 first nozzle

3 fuel nozzle

4 gas nozzle I

5 Gαsdüse Il

5.1 Gas nozzle II.1

6 Gαsdüse III

7 congestion ring

8 rejection throat

9 swirl element

10 cross section first nozzle

1 1 Annular cross section of fuel nozzle

12 Annular cross section gas nozzle I

13 Annular cross section gas nozzle Il

13.1 Sum of cross sections of gas nozzle II.1

14 Annular cross section gas nozzle III

15 Longitudinal round burner or the first nozzle

16 longitudinal axis gas nozzle II.1

17 Gas nozzle outlet area

18 burner throat

Claims

Pαtentαnsprüche 1 . Round burner for burning fossil fuels, comprising: a first nozzle (2) for introducing an air or Rezigαsstromes or a Mixture of O ₂ or air and Rezigas, a coaxial with the first nozzle (2) arranged and this enveloping and a Circular ring cross-section (1 1) forming fuel nozzle (3) for the injection of Fuel, a coaxial with the first nozzle (2) arranged and the fuel nozzle (3) enveloping and a circular ring cross section (12) forming the gas nozzle 1 (4) for Introduction of an air or Rezigasstromes or a mixture stream of O ₂ or Air and Rezigas, a coaxial with the first nozzle (2) arranged and the gas nozzle 1 (4) enveloping and a circular ring cross-section (13) forming the gas nozzle Il (5) for initiating a Air or O ₂ stream or a mixture stream of O ₂ or air and Rezigas, a coaxial with the first nozzle (2) arranged and the gas nozzle Il (5) enveloping and a circular ring cross section (14) forming the gas nozzle III (6) for introduction one Air or Rezigasstromes or a mixture flow of O ₂ or air and Rezigas, wherein in the gas nozzle exit region (1 7), the surface of the circular ring cross-section (13) the gas nozzle II (5) in the ratio of 1, 2 to 2.0: 1 to the surface of the Annular cross section (12) of the gas nozzle 1 (4) and the area of the Annular cross section (14) of the gas nozzle III (6) in the ratio of 0.2 to 0.8: 1 to the surface of the circular ring cross section (12) of the gas nozzle 1 (4) and the surface of Cross-section (10) of the first nozzle (2) in the ratio of 0.01 to 0.1: 1 to the Surface of the circular ring cross-section (12) of the gas nozzle 1 (4). 2. A round burner for burning fossil fuels, comprising: a first nozzle (2) for introducing an air or Rezigasstromes or a mixture stream of O ₂ or air and Rezigas, a coaxial with the first nozzle (2) arranged and enveloping and a Circular ring cross-section (1 1) forming fuel nozzle (3) for the injection of Fuel, a coaxial with the first nozzle (2) arranged and the fuel nozzle (3) enveloping and a circular ring cross section (12) forming the gas nozzle 1 (4) for Introduction of an air or Rezigasstromes or a mixture stream of O ₂ or Air and Rezigas, a coaxial with the first nozzle (2) arranged and the gas nozzle 1 (4) enveloping and a circular ring cross-section (14) forming the gas nozzle III (6) for initiating a Air or Rezigasstromes or a mixture flow of O ₂ or air and Rezigas, at least three gas nozzles II.1 (5.1), which are inside the annulus cross-section (12, 14) of the gas nozzle 1 (4) or the gas nozzle 111 (6) for the introduction of an air or O ₂ - stream or a mixture stream of O ₂ or air and Rezigas, wherein in the gas nozzle exit region (1 7), the area of the cross sections (13.1 ) of all gas nozzles II.1 (5.1) in a ratio of 1, 2 to 2.0: 1 to the area of the Annular cross section (12) of the gas nozzle 1 (4) and the area of the Circular cross-section (14) of the gas nozzle III (6) minus the Total cross-sectional area (13.1) of the gas nozzles II.1 (5.1) in the ratio of 0.2 to 0.8: 1 to the surface of the circular ring cross-section (12) of the gas nozzle 1 (4) and the Area of the cross section (10) of the first nozzle (2) in the ratio of 0.01 to 0.1: 1 to the surface of the circular ring cross-section (12) of the gas nozzle 1 (4). 3. Round burner according to claim 1 or 2, characterized in that one of the gas nozzles I, II or III (4, 5, 6) or the gas nozzles II.1 (5.1) is formed in its entirety or are such that whose cross section (12, 13, 14) in the oxyfuel operating the entire amount of oxygen required for combustion of the round burner (1) introduced fuel over this a cross section (12, 13, 14) or in the case of the gas nozzle II.1 (5.1) Total cross section (13.1) can be introduced. 4. Round burner according to one of claims 1 to 3, characterized in that at least one of the nozzles of the first nozzle (2), the fuel nozzle (3), the gas nozzle 1 (4), the gas nozzle Il (5) or the gas nozzle III (6) is formed with a storage ring (7). 5. Round burner according to one of claims 1 to 3, characterized in that at least one of the nozzles of the first nozzle (2), the fuel nozzle (3), the gas nozzle 1 (4), the gas nozzle 11 (5) or the gas nozzle 111 (6) is formed with a Abweiskehle (8). 6. Round burner according to one of claims 1 to 5, characterized in that at least one of the nozzles of the first nozzle (2), the fuel nozzle (3), the gas nozzle 1 (4), the gas nozzle Il (5) or the gas nozzle III (6) is formed with swirl elements (9). 7. Round burner according to claim 6, characterized in that the respective swirl elements (9) of the first nozzle (2) and the fuel nozzle (3) are twisted in the same direction or in opposite directions to each other. 8. Round burner according to claim 6, characterized in that at least at one of the gas nozzles I, II or II.1 or III (4, 5, 5.1, 6) the swirl elements (9) are designed to be adjustable in burner operation. 9. Round burner according to one of claims 1 to 8, characterized in that the width (s) of the annular gap of the circular ring cross-section (1 1) of the fuel nozzle (3) is at least 20 mm. 10. Round burner according to claim 2, characterized in that the longitudinal axes (16) of the gas nozzles 11.1 (5. 1) are arranged parallel or inclined to the longitudinal axis (15) of the first nozzle (2). 1. A method for operating a round burner according to the features of claim 1 or 2.