WO2009033835A1

WO2009033835A1 - Coal dust combination burner having a laser ignition device

Info

Publication number: WO2009033835A1
Application number: PCT/EP2008/058051
Authority: WO
Inventors: Tino Just; Christian Reuther; Manfred Schingnitz
Original assignee: Siemens Aktiengesellschaft
Priority date: 2007-09-12
Filing date: 2008-06-25
Publication date: 2009-03-19
Also published as: DE102007043428A1

Abstract

The invention comprises a pilot burner, which can be integrated into a coal dust combination burner for the gasification of powdery fuels having an oxidizing agent containing free oxygen at ambient or higher pressures and temperatures between 800-1800°C, wherein a laser beam generated in a laser source (8) can be guided through a quartz glass and a central pipe (1) into the reaction chamber, wherein the laser beam is focused such that the burning point is positioned in the mixed region of the oxidizing agent and the burnable gas.

Description

description

Coal dust combination burner with laser igniter

The invention relates to a pulverized coal burner which is used for the gasification of coal dust at high pressure and temperature. These consist essentially of a dust burner (main burner), which is arranged concentrically around a pilot burner. Both burners are operated with oxygen and work in the sub-stoichiometric range.

The pilot burner has two main tasks to accomplish: First, the pilot burner provides the ignition energy to ignite the main burner flame, and second, it maintains a permanent ignition potential for the main burner and increases pressure. The ignition of the pilot burner itself must be carried out in a closed reaction space without direct access from the outside at a slight overpressure (about 3 bar). This ignition is usually done by means of sparks.

The invention relates to a pilot burner for an entrained-flow gasifier for the gasification of pulverulent fuels with an oxidant containing free oxygen at pressures between ambient pressure and high pressures of 80 bar (8 MPa) and temperatures between 800-1800 ⁰ C with the features of claim 1.

Carbon dust burners are known for the partial oxidation of dust-like fuels which are ignited by an externally arranged pilot burner.

In the patent DD 285 523 a generic pilot burner for the partial oxidation of gaseous hydrocarbons to CO and H2-containing gases in a pressurized reactor is described.

This pilot burner consists of coaxial channels for fuel gas and oxidant, which are open to the reaction space and separated by channels through which water flows or are enveloped. In the fuel gas channel, an ignition cable is arranged, which is connected to a Hochspannungszündvorrichtung outside the burner and merges at its end facing the reaction space in a metallic electrode, which is guided to the burner tip and here forms a spark gap to the metallic wall. The electrode of this burner is positioned in the fuel gas channel so that it passes through the confuser, annular nozzle and diffuser forming the nozzle and has the spark gap to the metallic wall at the paraxial curvature of the diffuser, ie in the vortex region forming the transition to the oxygen channel , The arrangement of the metallic electrode is chosen so that on the one hand enables the direct ignition of the fuel gas / oxygen and on the other hand, the metallic electrode is cooled by the inflowing fuel gas.

The high-voltage ignition cable is introduced into the burner by means of two separate pressure seals. The resulting pressure-tight space is used as a safety zone against leaking fuel gas leaks and monitored pressure side.

Further combinations of combination burners consisting of an ignition, pilot and dust burner are described in:

- Sino German Gasification and CDM Form of 5.-6. August

2004 in Beijing

"Lignite and Coal Gasification for Syngas and Energy Gas Production" and

Chinese Patent Application No. CN 200520110716 of June 24, 2005 from the Beijing Aerospace Power Institute

"Vortex burner with flammable powder as fuel"

The transmission of the flame signal to the monitoring device by means of a multicore optical cable. The well-known pilot burner has the following defects.

the transmission of the flame signal from the reaction chamber to the flame detector takes place by means of a light guide , which is thermally stressed by the small distance to the flame and at the same time can be limited by impinging soot particles in the field of view. In addition, the metallic electrode located in front of the optical insight obstructs the free view into the reaction space.

For reasons of space, the metallic electrode must be designed as a wire, which is bent several times up to the electrode tip. By means of this unstable structure, the adjustment necessary for the ignition at the sparkover point can only be adjusted with difficulty. This causes ignition problems and the functionality of the burner is not always guaranteed. - The design of the water-cooled nozzle (confuser, cylinder and diffuser) is very complicated and leads, especially in the diffuser to thermal stresses that lead to cracking in the material and thus to the failure of the burner. - Due to the arrangement of the electrode tip within the diffuser of the nozzle necessarily forms a vortex area at this point, which mixes oxygen with the fuel and thus forms an ignitable mixture that can be ignited. If it comes to media fluctuations during the ignition, the vortex area and thus the mixture point shifts, which leads to misfiring. An increased susceptibility to interference is thus given.

The combination burner according to the Chinese patent application no. CN 2005 201 10716 is further characterized in that the pilot burner gas, and the associated oxygen flow through a common channel in the burner center to the burner mouth. This entails the great danger that when the flow velocity changes, as occurs during internal and external operations, a backfire into the burner channel occurs, which leads to its destruction with considerable danger to operational safety. The object of the invention is to provide a pilot burner which can be integrated into a pulverized coal combustion burner and in which the necessary ignition energy can be supplied in a non-wired manner.

The object is solved by the features of claim 1.

According to the invention, a laser beam of sufficiently high power is passed through the burner into the reaction space via optical detection, wherein the laser beam is focused in front of the burner mouth in the region of the mixture of fuel gas and oxygen. By focusing the laser beam in this area, the energy density is increased locally, so that thereby the fuel gas-oxygen mixture is ignited.

By forming the flame in the central axis of the reactor, advantages over the previous solution with regard to burnout and conversion are achieved. At the same time, the media supply to the reactor head is unbundled. With the fitting of the pilot burner in the pulverized coal burner design changes were simultaneously made to the pilot burner, so that a functionally reliable and trouble-free operation can be ensured.

Advantageous developments of the invention are specified in the subclaims.

The invention is explained in more detail below as an exemplary embodiment in a scope necessary for understanding with reference to a figure. Showing:

1 shows an embodiment of the coal dust combination burner according to the invention with integrated pilot burner.

The coal dust combination burner according to the invention comprises a centrally arranged pilot burner part with separate fuel gas and oxidant supply in separate channels, a flame monitoring device 6 and a laser source 8. To this assembly, an annular space 13 for supplying the oxidizing agent for the coal dust combination burner is arranged. At the annular outlet opening swirl vanes 14 are arranged for swirling the Oxydationsmittelstromes. The outer contour of the pilot burner in the center and the inner tube of the outer main burner form the Hauptbrenneroxidationsmittelkanal (13). Around this channel and the inner cooling part 18, the pulverized coal feed 15 and the cooled outer shell 16 of the main burner are arranged.

The pilot burner comprises a centrally arranged, inert gas, in particular nitrogen flushed, tube 1, which serves as an optical inspection opening for the burner located outside the flame monitoring device 6, arranged around the central tube annulus 2 for fuel gas supply, another annular space 3 for Oxidydmittelzuführung on the End face is closed and merges into individual nozzle holes 4 and the whole enclosing water-flowed annular space 5 for supply and discharge of the cooling water.

The centrally arranged tube 1 is guided within the fuel gas channel 2 as far as the burner mouth and is purged with nitrogen in the direction of the reaction space in order to prevent the penetration of hot gas or impurities from the reaction space. Opposite the atmosphere, the central tube with a special quartz glass 12 is pressure-tight manner. The optical flame monitoring located outside the burner recognizes the burner flame through the quartz glass 12 and is therefore protected against thermal stress and dirt particles.

The nitrogen-purged central tube 1 serves as a channel for a laser beam. This is generated outside the burner (8) and aligned by means of adapters (11), for example, prism or semi-transparent mirror in the central tube. Of the

Laser beam is focused by means of suitable optics in such a way that the focal point in the mixed region of oxidation tel and fuel gas of the pilot burner (17) and ignites this ignitable mixture.

The annular space 2 located around the central tube for supplying the fuel gas is retracted at the outlet to the nozzle formation (reduced in cross-section).

The supply of the oxidant for the pilot burner via the annulus 3. This annulus is at the outlet to the reaction chamber out with a replaceable screw 10, which is provided with a plurality of holes 4, closed. These holes 4 may be adjusted depending on the nature of the fuel gas in diameter and exit direction.

The oxidant supply space 3 is enveloped by a water cooling system 5, which protects the internals and the nozzle of the pilot burner from thermal stress. To the water cooling 5 of the pilot burner, a further tube 19 is arranged, which serves as a carrier for exchangeable vertebral bodies 14 in Hauptbrenneroxydationsmittelkanal. By this inventive design of the shell around the pilot burner, the vertebral body 14 in the Hauptbrenneroxydationsmittelzu- guide can be quickly and easily changed during disassembly of the pilot burner and thus the main burner flame can be optimally adapted to the reaction space contour of the reactor.

By carrying out the oxidant supply with vertebral bodies / swirl vanes, the exiting oxygen flow is strongly set in rotation, into which the dust jets emerging via the specially designed supply elements 15 are sucked.

By a different employment of the vertebral bodies or swirl blades, the flame formation can be influenced in its width and length.

In a creative variant of the coal dust combination burner according to the invention, the annular spaces of the oxidizing tion medium supply (3) and the fuel gas supply (2) to be interchanged. Furthermore, it is possible to exchange the oxidant supply main burner (13) with the Brennstaubkanal (18) in position. In this case, the pulverized coal feed tubes (15) in the new fuel dust channel and the vertebral bodies (14) and the vertebral support tube (19) in the new oxidant supply main burner are to be arranged. A combination of both variants is possible.

The invention comprises a combination burner for the gasification of pulverulent fuels with a free oxygen-containing oxidizing agent at ambient or higher pressures, and temperatures between 800-1800 ⁰ C, wherein the combination burner of a gas-fired pilot burner with ignition and flame monitoring, arranged in the center of the combination burner is and a burner for dust-like fuel, which is arranged symmetrically around the pilot burner, wherein all operating channels separated from each other by water flowing through cooling channels led to the burner mouth and the media are mixed only at the burner mouth.

In a further embodiment of the invention, the combination burner comprises an outer water cooling part (16) and 2 to 6 carbon dust supply pipes (15) which are distributed over the circumference, the inner water cooling part (7) the boundary for receiving a centrally located pilot burner with external vertebral bodies (14) and at the same time forms the oxidant supply main burner (13). Furthermore, the centrally arranged pilot burner, consisting of a central tube (1) serves as an optical insight into the gasification chamber with external flame monitoring (6), a fuel gas supply (2) with screw-in nozzle (9), an oxidant supply (3) and water-cooled cooling chambers (5). Commissioning the pulverized coal burner unit, consisting of inner water cooling part (7), oxidant supply main burner (13), the vertebral body (14), coal dust supply pipes (15), outer water cooling part (16) and Brennstaubkanal (18). In a further embodiment of the invention, the central tube (1) is closed with respect to the atmosphere with a quartz glass (12) and carries on the non-pressurized side an optical flame detector, being flushable in the direction of the burner outlet opening with an inert medium, for example nitrogen, to make the penetration hotter Prevent gases from the reaction space.

In a further embodiment of the invention, the channel of the

Oxidant supply (3) in the region of the media outlet by means of a screw-in part (10) with nozzle holes (4), which are adaptable depending on the desired flame shape in the exit direction and exit angle.

In a further embodiment of the invention, the outer shell of the pilot burner with the inner cooling part (7) of the main burner part forms the Hauptbrenneroxydationsmittelkanal (13), which is equipped at the media outlet with exchangeable vertebral bodies (14) which are mounted on the Wirbelkörperträgerrohr (19) of the pilot burner and with the aid of which the flame geometry can be adapted in the reaction space.

In a further embodiment of the invention, a laser beam generated in a laser source (8) is guided by means of adapters (11) through the central tube (1) into the reaction space.

In a further embodiment of the invention, the guided through the central tube (1) in the reaction chamber laser beam is focused such that the focal point in the mixed region of O xidationsmittel and fuel gas (17).

In a further embodiment of the invention, the energy density at the focal point of the laser beam is so great that the fuel gas-oxidizing agent mixture in the mixed area of oxidizing agent and fuel gas (17) is brought to the ignition. In a further embodiment of the invention, the oxidizing agent supply main burner (13) including the vertebral body (14) and the vertebral carrier tube (19) and the Brennstaubkanal (18) including the pulverized coal feed tubes (15) are arranged reversed

In a further embodiment of the invention, the oxidizing agent supply pilot burner (3) and the fuel gas supply (2) are arranged reversed.

In a further embodiment of the invention, both the oxidizing agent supply main burner (13) including the vertebral body (14) and Wirbelkörperträgerrohr (19) and the Brennstaubkanal (18) including the Kohlenstaubzufüh- tubes (15) and the oxidant supply pilot burner (3) and the fuel gas supply (2) arranged reversed.

Reference sign list

1 central tube, flushed with nitrogen

2 fuel gas supply 3 oxidant supply pilot burner

4 nozzle bores

5 water-cooled refrigerators

6 flame monitoring

7 Inner water cooling part 8 Laser source

9 screw-in nozzle

10 screw-in part with holes

11 adapters

12 quartz glass 13 oxidant feed main burner

14 vertebral bodies in the main burner oxidant stream

15 coal dust feed pipes, 2 to 6 pieces distributed over the circumference

16 Outer water cooling section 17 Mixed area of oxidant and fuel gas

18 fuel dust channel

19 vertebral carrier tube

Claims

claims

1. pilot burner for an aerofoil gasifier for the gasification of pulverized fuels with a free-oxygen oxidant at pressures between ambient pressure and high pressures of 80 bar (8 MPa) and temperatures between 800-1800 ⁰ C, having the following characteristics

A central tube (1) substantially leading up to the burner mouth, around the central tube (1) substantially to the point of

Brennermund leading fuel gas ring channel (2) is concentrically arranged,

a fuel cell ring channel (3) is arranged concentrically around the fuel gas ring channel (2), substantially up to the burner mouth leading oxidant ring channel (3),

- The central tube (1) on the burner mouth facing away from the atmosphere with a quartz glass (12) is closed and in the direction of burner mouth with an inert medium, such as nitrogen, rinsed, - in a laser source (8) generated laser beam through the quartz glass and the central tube (1) can be guided into the reaction space and

- The laser beam is focused so that the focus is in the mixed region of oxidant and fuel gas (17) in front of the burner mouth.

2. pilot burner according to claim 1, characterized in that on the exposed to atmospheric pressure side of the quartz glass, a flame monitoring device (6) is arranged, which has an optical connection through the quartz glass in the reaction space.

3. pilot burner according to claim 2, characterized in that an adapter (11) is arranged on the acted upon by atmospheric pressure side of the quartz glass, the optical path of the laser beam and the optical path of the flame monitoring device separates.

4. Pilot burner according to claim 3, characterized in that the adapter has an optical prism for separating the optical paths.

5. Pilot burner according to claim 3, characterized in that the adapter has a semi-transparent mirror for separating the optical paths.

6. Pilot burner according to one of the preceding claims, characterized in that around the oxidant ring channel (3) a cooling water ring channel (5) is arranged concentrically.

7. pilot burner according to one of the preceding claims, characterized in that the pilot burner is supplemented by a main burner to a combination burner, wherein the main burner a Hauptbren- neroxidationsmittelkanal (13), a cooling water ring channel (7), an annular channel for supplying the dusty fuel (18) and a cooling water ring channel (16).

8. pilot burner according to claim 7, characterized in that the Hauptbrenneroxidationsmittelkanal (13) concentrically around the cooling water ring channel (5) is arranged, the cooling water ring channel (7) concentrically around the Hauptbrenneroxidationsmit- telkanal (13), the annular channel for supplying the dust-like fuel ( 18) is arranged concentrically around the cooling water ring channel (7) and the cooling water ring channel (16) is arranged concentrically around the annular channel for supplying the dusty fuel (18).

9. pilot burner according to claim 8 characterized in that the outer shell of the cooling water ring channel (5) has a Wirbelkörperträgerrohr (19) which is equipped in the region of the oxidant outlet with exchangeable vertebral bodies (14).

10. pilot burner according to claim 7, characterized in that the annular channel for supplying the dust-like fuel (18) is arranged concentrically around the cooling water ring channel (5), the cooling water ring channel (7) is arranged concentrically around the annular channel for supplying the dust-like fuel (18) said main burner oxidant passage (13) is disposed concentrically around said cooling water passage (7) and said cooling water passage (16) is concentrically arranged around said main combustor oxidant passage (13).

11. pilot burner according to claim 10, characterized in that the outer shell of the cooling water ring channel (7) has a Wirbelkörperträgerrohr, which is equipped in the region of the Oxidationsmit- telaustritts with exchangeable vertebral bodies (14).

12. Pilot burner according to one of the preceding claims, characterized in that

Fuel gas ring channel (2) and oxidant ring channel (3) are arranged reversed to each other.