KR20190024958A

KR20190024958A - burner

Info

Publication number: KR20190024958A
Application number: KR1020197000517A
Authority: KR
Inventors: 김익수
Original assignee: 두산 밥콕 리미티드
Priority date: 2016-06-08
Filing date: 2017-06-07
Publication date: 2019-03-08
Also published as: WO2017212255A1; GB201610007D0; GB2551166A; EP3469260A1

Abstract

A primary conduit for a burner having a primary conduit outlet is described; The primary conduit defining a primary conduit flow channel extending to the primary conduit outlet; The primary conduit having a primary conduit end pipe proximate to the primary conduit outlet forming a flow channel having a linear flow direction from the first inlet end to a corresponding second outlet end corresponding to the primary conduit outlet and a second conduit end pipe extending from the first inlet end to the first conduit end portion And a primary conduit elbow pipe upstream and in fluid communication with the primary conduit end portion forming a flow channel having a departure flow direction to a second outlet end corresponding to the inlet end. The primary conduit comprises, in its flow channel, a first vortex formation comprising at least one vortex vane at a first vortex position and at least one vortex vane at a second vortex position, And a second vortex sub-formation. A burner including such a primary conduit is described.

Description

burner

The present invention relates to a burner, and more particularly to a burner for combustion of particulate carbon fuel. In preferred cases, the present invention relates to a pulverized fuel burner such as a pulverized coal fired burner. For example, the present invention relates to a power generating device comprising a burner for use in a power generating device and one or more such burners. In the most general concept of the present invention, the present invention relates to a primary air conduit arrangement for such a burner and a burner including such a burner.

In general terms, a burner for the combustion of particulate carbonaceous fuel may comprise a number of components including:

A primary conduit for supplying a transfer gas, which may be a pulverous fuel and a comburant gas (sometimes known as "primary" air), to the burner outlet;

A large number of channels concentrically arranged around the primary conduit differential fuel feed, for example, can be supplied with combustion gases and other gases through such channels to support / control / modify combustion at the burner outlet ; In burners for the combustion of particulate carbon fuels, typically there will be more than one channel for combustion air or other combustible gases, and combustion air or other combustible gases are often referred to as "secondary" air, "tretiary" "A large number of channels, known as air;

• To provide additional burner gas, for example, to assist / control / modify combustion at the burner outlet, and / or to position auxiliary equipment such as an igniter, light-up burner, flame monitoring sensor, A core conduit or core tube axially centered within an annular primary conduit;

A device for inducing a swirling motion into a gas flow, for example in a secondary and tertiary (equal) channel;

A device for flame stabilization, often placed at the end of the fuel supply pipe and sometimes known as a "flame-retainer ";

A device disposed inside the fuel supply pipe for controlling the fuel distribution at the outlet of the fuel supply pipe;

As an auxiliary equipment such as an igniter, a light-up burner, a flame monitoring sensor or the like, which may be centrally located in a fuel pipe known as a "core" The core tube may have its own air or other gas supply; Which can alternatively be installed in or close to another location in the burner.

When "air" is used herein with reference to the prior art and with reference to the present invention, those skilled in the art will appreciate that the air, including air, and / or recirculated flue gas and / It will be readily appreciated that other gases, including combustor gases and mixtures, may be substituted in a familiar manner, such as oxyfuel ignition involving a reduced nitrogen combustor gas relative to the combustor gas. It will be appreciated that reference to combustor gas includes mixtures of gases including gases capable of supporting combustion and other gases.

The present invention relates to a primary conduit for a burner, as described above, configured to supply a particulate fuel and a transfer gas to a primary conduit outlet corresponding to a burner outlet; And a burner comprising such a burner; Such transport gas is typically combustor gas (sometimes known as "primary" air) in use.

The present invention relates to a primary conduit having a primary conduit inlet arranged to receive a supply of combustible particulate fuel and a supply of a combustor gas and a primary conduit outlet in which combustion of fuel during use is supported; The primary conduit forms (or defines) a flow channel that extends from the primary conduit inlet to the primary conduit outlet for transferring a mixture of gases, such as fuel and combustible gases, in use. The primary conduits are disposed annularly around the core conduit and may have secondary and tertiary channels as described above.

It is known to those skilled in the art that there are a large number of modified burner designs that can be used for the combustion of particulate carbon fuel. In the design of an optional burner, there is sufficient burner gas to supply sufficient oxidant in any oxidant / fuel mixture, and a uniform distribution of fuel in the oxidant to support constant burning of the fuel and to maintain the stability of the flame The requirement to ensure that there is

An alternative arrangement of a burner design effective to support a constant burning of the fuel and to produce a uniform distribution of the fuel in the oxidant to maintain the stability of the flame is desirable.

According to the present invention there is provided a primary conduit for a burner having a primary conduit outlet in use in which combustion of fuel is in use; The primary conduit forms a primary conduit flow channel extending in use to the primary conduit outlet for receiving and transporting a mixture of gas such as fuel and combustible gas;

The primary conduit having a primary conduit end pipe proximate to a primary conduit outlet forming a flow channel having a linear flow direction from a first inlet end to a second outlet end corresponding to the primary conduit outlet and a second conduit end pipe extending from the first inlet end to the first conduit end pipe A primary conduit elbow pipe upstream and in fluid communication with the primary conduit end pipe forming a flow channel having a direction of departure flow to a second outlet end corresponding to the inlet end;

Continuously in the downstream flow direction in the primary conduit end pipe within the annular flow channel around the core conduit:

A first swirler formation including at least one swirl vane at a first swirl position;

A second vortex subcomposition is located that includes at least one vortex vane at a second vortex position.

A change in direction when the fuel and gas mixture pass through the elbow pipe can create undesirable flow enrichment effects. The present invention seeks to mitigate this by creating a finite fuel and combustor flow distribution and concentration that improves combustion performance, as the finely divided fuel flows into and out of the end pipe.

The present invention accomplishes this by providing a combination of at least first and second eddy subformations as described above.

Each vortex vane includes a elongated vane formation disposed at an angle with respect to the primary conduit end pipe axis direction to provide a leading edge into the primary conduit flow channel in a familiar manner. Thereby, each vortex vane forms a pressure surface and a back surface and, in use, provides a pressure surface for flow in the primary conduit flow channel, thereby deflecting the flow.

Suitable swirling vane angles are between 20 ° and 60 °.

A vortex vane is disposed and configured so that the aforementioned deflection imparts rotational motion to the flow and deflects it. For example, a vortex vane includes a progressively curved vane formation that provides leading edges and progressively curved pressure surfaces for flow in the primary conduit flow channel in use.

The vortex vane may include elongated vane formation of a suitable cross-sectional shape including, for example, an L-shape, a rectangle, a triangle, a C-shape, a U-

The first and second vortex formation are arranged to create a more swirling flow towards the outside of the primary conduit flow channel to obtain a more uniform distribution of particle flow as the particle flow enters the end pipe from the elbow pipe. do.

One, the other, or both of the first and second eddy subformations preferably comprise a plurality of sets of vortex vanes. Advantageously, each vortex vane in such a plurality of sets is a geometrically congruent shape, except that it can be curved inversely.

Advantageously, the plurality of sets of vortex vanes include one or more pairs of vortex vanes. Advantageously, each vortex vane of the pair is disposed at the same angle but at an opposite angle to the primary conduit end pipe axis direction. Advantageously, each vortex vane in the pair is geometrically congruent, except that the vanes have an inversely curved progressive curve.

Advantageously, the plurality of sets of vortex vanes include two pairs of vortex vanes as described above. The first pair may be disposed at an opposite position by 180 degrees with respect to the second pair. For example, the first pair may be located on the elongate axis of the end pipe, within the uppermost portion of the primary pipe end pipe, and the second pair may be located on the lowermost portion of the primary pipe end pipe, Lt; / RTI >

The first vortex sub-formation is located at a first vortex location, the leading end of which is provided at a first location in the primary conduit flow channel, the first vortex sub- To the end. For example, the leading end is the leading edge of one or more vane formations as described above, which constitutes the first vortex formation, and the trailing edge is the trailing edge. Similarly, the second vortex sub-formation is located at a second vortex position downstream of the first vortex position, the leading end thereof is provided at a second position in the primary conduit flow channel, and the second vortex sub- Lt; RTI ID = 0.0 > downstream < / RTI > For example, the leading end is the leading edge of one or more vane formations as described above, which constitutes the first vortex formation, and the trailing edge is the trailing edge.

Advantageously, the first and second vortex sub-compositions are arranged overlapping and the second position of the leading end of the second vortex sub-composition has a length of the first formation between its leading end and its downstream end to some extent Follow. It is located, for example, at the midpoint of the length of the first formation.

In a possible embodiment, the primary conduit end pipe is coaxially disposed about the core conduit, and the core conduit forms a core flow channel for transferring additional gas flow, such as additional combustor gas flow, to the core conduit outlet, Thus, the primary conduit end pipe is disposed to form an annular flow channel about the core conduit.

Other constructions further configured to modify the flow may be provided within the primary conduit, particularly downstream of the vortex formation.

Optionally, a first particle diffuser may be provided, wherein the first particle diffuser comprises an axially mounted bullet formation such that the bullet formation progressively increases in the downstream flow direction, A first wall portion extending in a radially outwardly extending manner to provide a progressively increasing clog, and a second wall portion tapering in a radially inwardly extending manner to provide a progressively reduced clog of the primary conduit flow channel .

This provides the advantage that the bullet formation provides clogs that interact with the flow created by the vortex sub-formation to stabilize the distribution as the flow flows toward the burner outlet.

Optionally, the bullet formation may include a cylindrical third wall portion that is not tapered intermediate between the first and second wall portions.

Optionally, the bullet formation can be mounted so that it can translate axially back and forth along the burner. This provides the advantage of enabling control of particle distribution in the differential flow during use.

In embodiments involving a core conduit, the first particle diffuser may be mounted, for example, centered on the core conduit on the outer surface of the core conduit. The bullet formation may be mounted axially along the core conduit in an axial direction and slideably along the burner.

The first vortex subcomposition is preferably located in the primary conduit end pipe, generally at or immediately downstream of the point of communication between the primary conduit end pipe and the primary conduit elbow pipe, and is located, for example, in the transverse direction of the primary end pipe And is located downstream of the point of communication between the primary conduit end pipe and the primary conduit elbow pipe by a distance equal to or less than the diameter, for example. Alternatively, the first swirl subformulation may be located closer to the point of communication between the primary conduit end pipe and the primary conduit elbow pipe, e.g., less than 20% of the primary conduit end pipe diameter and optionally about 10% do.

The second vortex sub-formation is located further downstream but preferably overlaps with the first vortex sub-formation. The bullet formation, if present, is located further downstream and preferably beyond the second vortex sub-formation.

The present invention seeks to produce a flow of fractional fuel and combustor at a primary conduit outlet to improve combustion performance. The present invention achieves this by providing other optional structures, such as first and second vortex subcombination combinations and bullet formations as described above.

The primary conduits to which the principles of the present invention are otherwise applied are typically of a continuous flow for accommodating the supply of a gas such as a combustible gas and the supply of combustible particulate fuel and transporting it to the combustion location of the burner, The primary conduit having at least a primary conduit end pipe extending at least along the burner to a burner outlet and forming a linear flow direction parallel to the burner axis and an elbow portion immediately upstream of the primary conduit end pipe, , To form a departure flow direction that changes direction from the upstream flow direction upstream of the elbow portion to the downstream flow direction downstream of the elbow portion and downstream of the end pipe.

The core conduit optionally extends through the end pipe coaxially with the end pipe on the burner axis so that the outer surface of the core conduit and the inner surface of the end pipe form an annular primary flow channel, The surface forms a fluidly isolated core flow channel in a generally familiar manner.

The primary conduit end pipe preferably has a length at least three times its lateral extent, and in a typical case, the primary conduit end pipe is a cylinder at least three times its diameter.

The primary conduit comprises a primary conduit inlet arranged to receive a supply of a more completely combustible particulate fuel and a supply of gas such as a combustible gas and a primary conduit outlet in the vicinity of which combustion of the fuel is supported; The primary conduit forms a primary conduit flow channel extending from the primary conduit inlet to the primary conduit outlet for transferring a mixture of gases such as fuel and combustible gas in use; The primary conduit elbow pipe and the end pipe, to which the present invention is principally associated, are positioned continuously downstream of the primary conduit, contiguously toward the outlet.

The primary conduit is preferably in fluid communication with a supply of combustible particulate fuel and a supply of combustible gas at the primary conduit inlet.

In a more complete embodiment, there is provided a burner having a primary conduit as described above.

In this more complete embodiment, there is provided a burner having a burner inlet for receiving a supply of combustible particulate fuel and a supply of combustor gas, and a burner outlet in which combustion of the fuel in use is supported; The burner comprises:

And a primary conduit for transferring a mixture of gases, such as fuel and combustible gases, according to the first aspect described above.

The burner accordingly includes a primary conduit with a primary end pipe forming a flow channel for conveying a mixture of gases, such as fuel and combustible gas, for example coaxially disposed about the core conduit.

The present invention is characterized in that first and second vortex sub-formations and bullet formations as described above are provided in the primary conduit to produce a differential fuel flow and combustor distribution and concentration to improve combustion performance.

In accordance with this basic feature, the burner of the present invention may include additional elements for supplying the material to the burner outlet and / or for supporting combustion and flame stability at the burner outlet and / Allow.

Particularly alternatively, the burner may comprise at least one additional conduit, for example one or more secondary conduits, including an additional flow channel for supplying additional gas, such as additional burner gas, to the combustion site at the burner outlet, Gt; or higher order conduit. &Lt; RTI ID = 0.0 > Typically, such additional conduits are disposed about, for example, coaxial with, the primary conduit. Optionally, such additional conduits may include a vortex generating device for imparting a vortex to the gas flow therein.

The conduit may comprise any suitable arrangement forming a elongated flow channel. Each of the core, primary and, where applicable, secondary, tertiary, and higher order conduits may include one or more elongate structures that form elongated flow channels. In the case where the conduit comprises a plurality of flow channels, such conduits are, for example, generally parallel. In familiar designs, the core, primary, secondary, and tertiary or higher order conduits may be positioned about one another, e.g., axially, to form an axial flow in the burner elongated direction. For example, a core conduit may be provided along the burner axis, a primary conduit may be disposed about it, a secondary conduit may be additionally disposed therearound, and a tertiary and higher order conduit may additionally be provided around So as to form axial flow channels parallel to the burner elongated direction. Such an arrangement would be familiar.

Typically, for example, concentric and / or coaxial tubes, such as concentric and / or coaxial cylinders, may form annular flow regions or sectors for primary, secondary, and higher order conduits. For example, an annular flow channel comprising a single or a plurality of annular sectors may constitute a primary flow, a secondary flow and a tertiary flow as desired.

Preferably, the burner of the present invention is configured for combustion of particulate carbon fuel and, if desired, is a differential fuel burner. Preferably, the burner comprises a source of particulate carbon fuel for feeding the fuel to the burner inlet, and more particularly to the inlet of at least the primary conduit.

Preferably, the fractional fuel burner is an undifferentiated coal burner, for example a bituminous coal or a burner for dried, undifferentiated low grade coal. As a consequence, preferably the finely divided fuel is undifferentiated coal, such as undifferentiated bituminous coal or dried and undifferentiated low grade coal. Alternatively, the burner of the present invention may be configured for combustion of a pulverized carbon fuel such as biomass, pulverized carbon waste material, and the like.

In a more complete aspect of the invention, a combustion device is provided, and such combustion device comprises:

Combustion chamber; And

And at least one and preferably a plurality of burners as described above positioned to form a combustion site within the combustion chamber.

Preferably, the combustion device comprises a boiler for generating steam.

Preferably, the fuel used is particulate carbon fuel and, if desired, a particulate fuel, most preferably an undifferentiated coal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, preferred embodiments of the present invention will be described, by way of example only, with reference to the accompanying drawings.
Figure 1 shows an example of a possible embodiment of the invention.
Figure 2 shows design / dimension considerations for the embodiment of Figure 1;

1 shows an example of a possible embodiment of the present invention in which a primary air elbow pipe 1 is led through a primary air end pipe 3 to a burner outlet 7. The elbow pipe forms a 90 degree change in the flow direction and the end pipe provides a linear axial flow direction at the burner outlet having a length at least three times the diameter. Together they form a downstream portion of the primary conduit arranged to deliver the combustible particulate fuel and the feed of the combustor gas to the primary conduit outlet where combustion of the fuel is in use during use. The primary conduit is annularly disposed about the core conduit 5 to supply core air to the burner outlet. Other conduits (not shown) may be included in a familiar manner in a complete burner design.

The primary flow channels formed by the primary conduits are progressively downstream along the first set 9a and the second set 9b of vortex vanes and the bullet formation 15 projecting outwardly from the outer surface of the core conduit ). Each of which is mounted axially about the burner axis. Bullet structures may be mounted around the core conduit and axially translated along the burner.

In the illustrated embodiment, each of the first set 9a and the second set 9b of vortex vanes comprises a set of four vanes arranged in two pairs. The first pair is shown above, and the second pair is shown below. Each vane in the pair faces the pressure surface in an axial flow direction in the end pipe at an angle to provide a leading edge so that the two members of the pair are mirrored when viewed from the axial direction pairs, which are essentially identical. That is, each member of the pair forms an angle at the same angle but opposite to the pipe axis direction. If the vanes have gradual curves, the vanes are likewise curved inversely.

The first vortex sub-formation is preferably located in the primary conduit end pipe, immediately downstream of the point of communication between the primary conduit end pipe and the primary conduit elbow pipe, thereby forming a first vane in which the leading edge of the first vane is disposed Thereby forming a starting point 11a. The second vortex sub-formation is located further downstream of the first vortex sub-formation, thereby forming a second vane start point 11b at which the leading edge of the second vane is disposed. In this embodiment, the second starting point is located in the middle of the length of the first vane so that the two sets overlap. The bullet formation is located beyond the second vortex sub-formation and further downstream.

The vortex vane tends to produce vortex flow only at the outer side in order to obtain a more uniform particle distribution within the PA end tube and to stabilize the flow. The illustrated embodiment shows two sets of four vanes + four vanes, wherein the starting points are different so that the second set starts at the middle length of the first set vortex. Other different sets were tested, such as the degree of insertion (types A and B). The two sets more efficiently break the flow and the swirl motion is maintained by the second set swirl. The bullet then acts to re-distribute the particles and stabilize the flow. It can be moved up and down to control mixing and flow.

Flow patterns are shown and suitable design parameters are considered with reference to FIG.

The flow generally changes from an elbow pipe bending flow to a linear flow in the PA end pipe. Two typical representative flows are shown. The vortex vane arrangement produces an outer vortex flow "A " and a linearized inner flow" B ". A protective sleeve 17 for the core pipe / bullet and a protective liner 19 for the inner surface of the end pipe can be provided.

Suitable design parameters are as follows.

● Non swirler area "B" for PA area "C" (protective sleeve inside diameter)

- 40%? B / C? 70%

- recommended 50% ≤ B / C ≤ 60%

- The swirl height can be obtained accordingly.

● Thickness of whirlpool vane:

- 40mm is used here

- Depending on the erosion, the thickness may change.

Vortex angle vane ●

- 20 ° ≤ whirlpool vane ≤ 60 °

- Recommended 45 °

- The smaller the angle, the longer the vane length.

● PA pipe length "L"

- L? 1.5 x? PA

- recommended L ≥ 3 × φPA

● Elbow bending radius "R"

- R? C / 2

- where R = C is used

● 10% ≤ Bullet blocking ≤ 40%

- Recommended 20%

(60%? Area ratio E / C? 90%)

● Bullet position "K", K ≥ 0 mm

- Recommended, K ~ 100mm from the end of the whirlpool.

These and other combinations and variations of the principles of the present invention are directed to an end pipe outlet which improves combustion performance by alleviating undesirable flow concentration effects due to directional changes as the fuel and gas mixture is delivered into the end pipe through the elbow pipe Fuel mixture and combustor flow distribution and concentration at the < / RTI >

Claims

A primary conduit for a burner having a primary conduit outlet; The primary conduit defining a primary conduit flow channel extending to the primary conduit outlet;
Said primary conduit having a primary conduit end pipe proximate to said primary conduit outlet forming a flow channel having a linear flow direction from a first inlet end to a second outlet end corresponding to said primary conduit outlet and a second conduit end pipe upstream of said primary conduit end pipe And a primary conduit elbow pipe in fluid communication therewith and forming a flow channel having a departure flow direction from a first inlet end to a second outlet end corresponding to an inlet end of the primary conduit end pipe;
Within the primary conduit end pipe in the annular flow channel around the core conduit continuously in the downstream flow direction:
A first vortex formation including at least one vortex vane in a first vortex position;
And a second vortex formation comprising at least one vortex vane at a second vortex position is located.

The method according to claim 1,
Each vortex vane comprises a elongated vane formation disposed at an angle with respect to the primary conduit end pipe axis direction to provide leading edge into the primary conduit flow channel thereby forming a pressure surface and a back surface, To provide a surface for flow within the primary conduit flow channel.

3. The method according to claim 1 or 2,
Each vortex vane comprises a progressively curved vane formation providing a leading edge and a progressively curved pressure surface for flow in the primary conduit flow channel.

4. The method according to any one of claims 1 to 3,
Each vortex vane comprising a vane formation of a vane angle of 20 [deg.] To 60 [deg.] With respect to the primary conduit end pipe axis direction.

5. The method of claim 4,
Each vortex vane including a vane formation of a vane angle of 45 DEG with respect to the primary conduit end pipe axis direction.

6. The method according to any one of claims 1 to 5,
Wherein one, the other, or both of the first and second vortex formations comprises a plurality of sets of vortex vanes.

The method according to claim 6,
Each vortex vane in the plurality of sets is geometrically congruent, except that some may be reversed.

8. The method according to claim 6 or 7,
Wherein the set of plurality of vortex vanes comprises at least one pair of vortex vanes.

9. The method of claim 8,
Wherein each vortex vane of the pair is disposed at the same angle but in the opposite direction with respect to the primary conduit end pipe axis direction.

10. The method according to claim 8 or 9,
Each vortex vane in the pair is a geometric co-ordinate, primary conduit, except that the vanes have an inversely curved progressive curve.

11. The method according to any one of claims 8 to 10,
Wherein the plurality of sets of vortex vanes include exactly two pairs of vortex vanes having a first pair disposed at a position 180 degrees opposite to the second pair.

12. The method according to any one of claims 1 to 11,
Wherein the first vortex sub-formation is located at a first vortex location, the leading end thereof is provided at a first location in the primary conduit flow channel, and the second vortex sub- formation is located at a second vortex location downstream of the first vortex location, And the leading end thereof is provided at a second location in the primary conduit flow channel downstream of the first location and the first and second vortex subcompositions are arranged to overlap, Wherein the second position of the leading end follows to some extent the length of the first formation between its leading and trailing ends.

13. The method according to any one of claims 1 to 12,
The primary conduit end pipe is disposed coaxially about a core conduit and the core conduit forms a core flow channel for transferring additional gas flow, such as additional combustor gas flow, to the core conduit outlet, Wherein the conduit end pipe is disposed to form an annular flow channel about a core conduit.

14. The method according to any one of claims 1 to 13,
Wherein the bullet formation includes a first wall portion extending in a radially outwardly extending manner to provide progressively increased clogging of the primary conduit flow channel in a downstream flow direction, And a second wall portion that is tapered in a radially inwardly extending manner to provide progressively reduced clogging of the primary conduit flow channel, and a second wall portion that is tapered in an inwardly extending manner to provide a progressively reduced clogging of the primary, Primary conduit, including wall portion.

15. The method according to any one of claims 1 to 14,
Wherein the bullet formation includes a cylindrical third wall portion that is not tapered midway between the first and second wall portions.

16. The method according to any one of claims 1 to 15,
Wherein the bullet formation is mounted so that it can translationally move axially along the burner.

17. The method according to any one of claims 1 to 16,
Said primary conduit end pipe having a length at least three times its lateral extent.

18. The method according to any one of claims 1 to 17,
Further comprising a primary conduit inlet arranged to receive a supply of a combustible particulate fuel and a gas such as a combustible gas; The primary conduit forming a primary conduit flow channel extending from the primary conduit inlet to the primary conduit outlet for transferring the mixture of fuel and gas to the outlet; Wherein the primary conduit elbow pipe and the end pipe are positioned continuously downstream of the primary conduit and toward the outlet.

19. The method of claim 18,
A primary conduit in fluid communication with a supply of combustible particulate fuel and a supply of combustor gas at the primary conduit inlet.

A burner inlet having a burner inlet for receiving a supply of combustible particulate fuel and a supply of combustor gas and a burner outlet in which combustion of fuel during use is supported; Wherein the burner comprises a primary conduit according to any one of claims 1 to 19.

21. The method of claim 20,
At least one additional conduit, for example one or more secondary conduits, including an additional flow channel for supplying additional gas, such as additional combustible gas, to the combustion site at the burner outlet, and optionally one or more tertiary or higher A burner further comprising a conduit of degree.

22. The method according to claim 20 or 21,
A burner configured for combustion of particulate carbon fuel, such as undifferentiated coal.