EP2181287B1 - Combined pulverized coal burner comprising an integrated pilot burner - Google Patents

Description

The invention relates to a Kohlenstaubkombinationsbrenner, which is used for the oxygen gasification of dust-like fuels (lignite and / or hard coal or similar dusty fuels) under high pressures and temperatures in reactors with liquid slag and by means of an integrated pilot burner with gaseous fuel and Oxygen works and is put into operation and monitored with an electric ignition device and optical flame monitoring.

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

• Sino German Gasification and CDM Form vom 5.-6. August 2004 in Beijing "Lignite and Coal Gasification for Syngas and Energetic Gas Production" und
• Chinesische Patentanmeldung Nr. CN 200510079702.4 vom 24. Juni 2005 vom Beijing Aeronautical Power Inst. "Powder-combustible vortex burner"

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 documents EP 0363787 A1 and DD 285 523 each generic pilot burner for the partial oxidation of gaseous hydrocarbons to CO and H2-containing gases are described in a pressurized reactor.
Such a pilot burner consists of coaxial channels for fuel gas and oxidant, which are open towards the reaction space and which are separated or enveloped by channels through which water flows. 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 passage so as to pass through the confuser, annular nozzle forming the nozzle and diffuser passes and at the axis-parallel radius of curvature of the diffuser, ie in the vortex region, which forms the transition to the oxygen channel, the spark gap to the metallic wall has. 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 Energetic Gas Production" and
• Chinese Patent Application No. CN 200510079702.4 of June 24, 2005 from the Beijing Aeronautical Power Inst. "Powder-combustible vortex burner"

• die Übertragung des Flammensignals aus dem Reaktionsraum zum Flammenwächter erfolgt mittels Lichtleitkabel, das durch den geringen Abstand zur Flamme thermisch belastet wird und gleichzeitig auch durch auftreffende Russpartikel im Sichtfeld eingeschränkt werden kann. Außerdem behindert die vor den optischen Einblick befindliche metallische Elektrode den freien Einblick in den Reaktionsraum.
• Die metallische Elektrode muss aus Platzgründen als Draht ausgeführt werden, der bis zur Elektrodenspitze mehrfach gebogen ist. Durch dieses instabile Gebilde kann die zur Zündung notwendige Justierung an der Funkenüberschlagstelle nur schwer exakt eingestellt werden. Hierdurch entstehen Zündstörungen und die Funktionstüchtigkeit des Brenners ist nicht immer gewährleistet.

• Die Ausführung der wassergekühlten Düse (Konfusor, Zylinder und Diffusor) ist sehr kompliziert und führt besonders im Diffusor zu thermischen Belastungen, die zur Rissbildung im Material und damit zum Ausfall des Brenners führen.
• Durch die Anordnung der Elektrodenspitze innerhalb des Diffusors der Düse bildet sich notwendigerweise an dieser Stelle ein Wirbelgebiet aus, das Sauerstoffanteile mit dem Brennstoff mischt und damit ein zündfähiges Gemisch bildet, das gezündet werden kann. Kommt es bei der Zündung zu Medienschwankungen verschiebt sich das Wirbelgebiet und damit die Gemischstelle, was Fehlzündungen zur Folge hat. Eine hohe Störanfälligkeit ist damit vorgegeben.

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 is carried out by means of fiber optic cable, which is thermally stressed by the small distance to the flame and can also 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 has to be designed as a wire, which is repeated up to the electrode tip is bent. 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 the failure of the burner.
• The arrangement of the electrode tip within the diffuser of the nozzle necessarily forms a vortex area at this point, which mixes oxygen fractions with the fuel and thus forms an ignitable mixture which can be ignited. If it comes to media fluctuations during the ignition, the vortex area and thus the mixture point shifts, which results in misfiring. A high susceptibility to interference is thus predetermined.

The combination burner according to the Chinese patent application no. CN 200510079702.4 is also characterized by the fact that the pilot burner gas, and the associated oxygen flow through a common channel in the burner center the burner mouth. This involves the great danger that when changing the flow velocity, as occurs during commissioning and decommissioning, a flashback occurs in the burner channel, which leads to its destruction with significant threats to operational safety.

From the GB 1001032 a burner for the simultaneous combustion of several different fuels is known, wherein each fuel a pair of concentric annular channels for this fuel or the oxygen are arranged, which open into a mixing chamber.

The invention is based on the objective, by constructive measures, a combination of pilot burner and pulverized coal burner in a burner unit as Kohlenstaubkombinationsbrenner The combination of both burners in one unit ensures a simpler and safer operation with even flame formation and minimizes the susceptibility to interference.

The object of the invention is to provide a simple pulverized coal burner with integrated pilot burner, which ignites reliably under the conditions of coal dust gasification under pressure and works safely.

The object is solved by the features of claim 1.

In the coal dust combination burner according to the invention a locally fixed and precisely adjustable spark gap is formed, which is designed very stable from the mechanical structure. The formation of the flame in the central axis of the reactor advantages over the previous solution in terms of burnout and sales 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.

• Fig. 1 ein Ausführungsbeispiel des erfindungsgemäßen Kohlenstaubkombinationsbrenners mit integriertem Pilotbrenner.

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

• Fig. 1 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 FÜ and an electrical High voltage ignition. To this assembly, an annular space 13 for supplying the oxidizing agent for the coal dust combination burner is arranged. At the annular Outlet openings are arranged swirl vanes 14 for swirling the Oxydierungsmittelstromes.
The outer cooling part 5 of the pilot burner in the center and the inner cooling part 18 of the outer main burner form the Hauptbrenneroxydationsmittelkanal 17. To this channel and the inner cooling member 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-flushed tube 1, which serves as an optical inspection opening for the located outside the burner flame monitoring device, arranged around the central tube annulus 2 for fuel gas supply, another annular space 3 for oxidant supply, which is closed at the end face and in individual Nozzle holes 4 passes as well as the whole surrounding outer pilot burner cooling part 5 for supply and discharge of the cooling water. To the outer cooling channel (5) of the pilot burner, a further tube 13 is arranged, which serves to hold exchangeable vertebral bodies, which serve for the directed supply of the main burner with oxidant.

The centrally located pipe 1 is guided within the fuel gas channel 2 to the burner mouth and at the end is unilaterally in a small, short electrode tip 6, which can ignite the ignition spark directed at the metal wall of the fuel gas supply. The metallic central tube is electrically interrupted in the front third and connected by a tubular insulator piece 7. The upper part of the central tube serves as a carrier of the introduced via a pressure-tight implementation ignition cable 8, whose end is connected to the burner mouth side part of the central tube after the insulation piece.
The central tube 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 outside of the burner Optical flame monitoring detects the burner flame through the quartz glass 12 and is thus protected against thermal stress and dirt particles.

The annular space 2 around the central tube for supplying the fuel gas is drawn in at the outlet to the nozzle formation (reduced in diameter). The outer, the annular space limiting tube contains in this region of the nozzle a ceramic insulating ring 9, which causes the reduction in diameter and prevents unwanted sparkover of high-voltage ignition of the central tube. Only directly at the outlet of this tube is again made metallic.

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 can serin depending on the nature of the fuel gas in diameter and outlet direction.
In addition to the holes 4 pointing in the direction of the reaction chamber, small holes 11 are still arranged in the screw-in part 10 and lead into the fuel gas channel.
About these two holes a small amount of oxidant is introduced into the fuel gas channel. These holes are arranged so that the small amount of oxidizing agent enters immediately above the electrode tip in the fuel gas channel and in this area an ignitable gas mixture is formed. Overall, a spatially fixed and precisely adjustable spark gap is formed by the sum of the structural configurations, which is made very stable by the mechanical structure.

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 13 is arranged, which serves as a carrier for exchangeable vertebral bodies 14 in Hauptbrenneroxydationsmittelkanal serves. As a result of this inventive design of the shell around the pilot burner, when the pilot burner is disassembled, the vertebral body 14 in the main burner oxidant supply 17 can be changed quickly and easily, and thus the main burner flame can be optimally adapted to the reaction chamber contour of the reactor.
By carrying out the oxidant supply with vertebral bodies, the exiting oxygen flow is strongly set into 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.

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 ° C, the ignition device of the pilot burner with flame monitoring and the dust burner are integrated as a combination burner and all operating channels from each other run separately to the burner mouth and the two are mixed only at the burner mouth.

In a further embodiment of the invention, the combination burner on a cooled outer housing 16 and a pulverized coal feed 15, the inner cooling part 18 serves to limit the inclusion of a centrally located pilot burner with external vertebral bodies 14 and at the same time forms the Hauptbrenneroxidationsmittelkanal 17, wherein the centrally located pilot burner for Commissioning the pulverized coal burner unit 15, 16, 17, comprising a central tube 1 as an optical insight into the gasification chamber with external flame monitoring, a fuel gas supply 2, an oxidant supply 3 and a combustion cooling chamber 5 is used.

In a further embodiment of the invention, the central tube (1) within the fuel gas channel (2) led to the burner mouth and at the outlet on one side into a small short electrode tip (6), which directed at the high voltage ignition the spark on the opposite outer metal wall of the Fuel gas supply channel (2) passes.

In a further embodiment of the invention, the metallic central tube (1) is interrupted in the front third and connected by an insulator (7).

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 whereby it is in the direction of the burner outlet opening with an inert medium, such as nitrogen, flushable to the penetration of hot gases to prevent from the reaction space.

In a further embodiment of the invention, the central tube (1) on the outside serves as a carrier for the isolated Hochspannungszündkabel (8) wherein the metallic end of the Hochspannungszündkabels (8) with the burner near the burner piece of the metallic central tube (1) (behind insulator 7) is to conduct the high voltage to the electrode tip (6).

In a further embodiment of the invention, the fuel gas supply channel (2) in the region of the constriction to the outlet nozzle on the outer channel boundary on a ceramic insulator (9) to prevent an uncontrolled high-voltage sparkover at the bottleneck.

In a further embodiment of the invention, the oxidant supply channel (3) in the region of the media outlet by means of a screw-in (10) with nozzle holes (4) over, which are adaptable depending on the desired flame shape in the exit direction and exit angle.

In a further embodiment of the invention are in the screw (10) on Oxidydmittelzuführungskanal (3) additionally small holes (11) arranged in the fuel gas channel (2) and thus a small amount of oxidant immediately above the electrode tip (6) in the nozzle region of the fuel gas channel ( 2) and locally form an ignitable mixture which is ignitable by the high voltage ignition spark.

In a further embodiment of the invention, the outer shell of the pilot burner with the inner cooling part (18) of the main burner part forms the Hauptbrenneroxydationsmittelkanal (17) which is equipped at the media outlet with exchangeable vertebral bodies (14) which are mounted on the outer shell (13) of the pilot burner and with the aid of which the flame geometry in the reaction space can be adapted.

In a further embodiment of the invention, the pulverized coal via one or more tangentially ending coal dust feed tubes (15) is introduced into the combination burner wherein the pulverized coal in the front burner part in a Kohlenstaubzuführungsrohren common Kohlenstaubringraum (19) enters and here under rotary motion fills the Kohlenstaubringraum and as evenly Distributed pulverized coal veil leaves the annulus and is intensively mixed in front of the burner mouth with the oxidant stream.

LIST OF REFERENCE NUMBERS

1

Central tube for visual inspection into the reaction chamber with external flame monitoring, nitrogen-purged.

2

Fuel gas supply

3

Oxydationsmittelzuführung

4

Nozzle holes in the oxidant feed

5

Cooling part pilot burner

6

electrode tip

7

Isolator on the central tube 1

8th

High-voltage ignition cable

9

Ceramic insulator in fuel gas supply duct

10

Threaded part with holes

11

Ignition holes for oxidant injection

12

quartz glass

13

Support tube for vortex devices

14

Vertebral body in the main burner oxidant stream

15

Pulverized coal supply

16

Outer water cooling part

17

Hauptbrenneroxydationsmittelzuführung

18

Inner water chiller main burner

Claims (8)

1. Combination burner for the gasification of pulverised fuels with an oxidation means containing free oxygen for pressures between ambient pressure and high pressures of 80 bar (8 MPa) as well as temperatures between 800-1800°C, with the following features:

   - a central tube (1) essentially leading to the mouth of the burner (1),

   - arranged concentrically around the central tube (1) is an annular combustion gas channel (2) essentially leading to the mouth of the burner,

   - arranged concentrically around the annular combustion gas channel (2) is an annular oxidation means channel (3) essentially leading to the mouth of the burner,

   - arranged concentrically around the annular oxidation means channel (3) is an annular cooling channel (5),

   - arranged concentrically around the annular cooling channel (5) is an annular channel for the oxidation means of the pulverised fuel burner (17),

   - arranged concentrically around the annular channel for the oxidation means of the pulverised fuel burner (17) is an annular coolant channel (18),

   - arranged concentrically around the annular coolant channel (18) is an annular channel for the fuel of the pulverised fuel burner (15),

   - arranged concentrically around the annular channel for the fuel of the pulverised fuel burner (15) is an annular coolant channel (16), characterised in that

   - the central tube (1) supports an ignition tip (6) electrically insulated from the burner,

   - the insulation is implemented by a central tube (1) separated into two tube sections and the tube sections are mechanically connected by a tubular, ceramic insulating body (7),

   - the central tube (1) serves as a support for an insulated high-voltage ignition cable (8), wherein the metallic end of the high-voltage ignition cable (8) is connected to the section of the metallic central tube (1) located in the vicinity of the mouth of the burner which carries the ignition tip.
2. Combination pulverised fuel burner according to one of the previous claims,
   characterised in that
   the central tube (1) has a pressurised optical viewing window for flame monitoring at its end facing the mouth of the burner and is able to be flushed with an inert gas.
3. Combination pulverised fuel burner according to one of the previous claims,
   characterised in that
   the annular oxidation means channel (3) is closed off on the burner mouth side by an annular screw-in part (10) with nozzle holes (4). (A6)
4. Combination pulverised fuel burner according to one of the previous claims,
   characterised in that
   the combustion gas supply channel (2) has a ceramic insulating cladding (9) in the area of the constriction to the outlet nozzle. (A7)
5. Combination pulverised fuel burner according to claim 3 or 4,
   characterised in that
   the constriction of the combustion gas supply channel (2) is implemented by the annular screw-in part (10) of which the central hole has a smaller diameter than the internal diameter of the combustion gas supply channel (2). (A8)
6. Combination pulverised fuel burner according to one of the claims 3 to 5,
   characterised in that
   small holes (11) are arranged in the screw-in part (10), which lead into the annular combustion gas channel (2) in the immediate vicinity of the ignition tip (6). (A9)
7. Combination pulverised fuel burner according to one of the previous claims,
   characterised in that
   arranged around the annular coolant channel (5) is a tube (13) which serves as a support for replaceable eddy bodies (14) in the annular channel for the oxidation means of the pulverised fuel burner (17). (A10)
8. Combination pulverised fuel burner according to one of the previous claims,
   characterised in that,
   the annular channel for the oxidation means of the pulverised fuel burner (17) and the annular channel for the fuel of the pulverised fuel burner (15) are arranged to be mutually interchangeable. (A11)

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