DD228987A3 - COAL DUST pilot burner - Google Patents

Abstract

The invention relates to a pulverized coal Zuendbrenner for the operation with moist coal dust, with dust humidities up to 25% with a Kern class B should be allowed without a long-term Zuendbrenner use. It should be ensured via a controllable medium, a preheating of the burner and the pulverized coal and a control of the pulverized coal air flow rate. Furthermore, an internal and external recirculation is to be achieved in order to ensure rapid startup of the components of the ignition burner. This is achieved in that the outlet of the inner tube is connected to a return step forming, known muffle, the return stage is formed by an extension of the muffle to the inner tube in diameter ratio of 1.5 to 2.5, outside the muffle one Secondary air supply is arranged and / or that the Ejektorringduese is connected to a mixing tube. Fig. 1

Description

Title of the Invention Coal dust pilot burner

Field of application of the invention

The invention relates to a pulverized coal firefighting machine for operation with moist pulverized coal.

Characteristic of the known technical solutions

To ignite a pulverized coal-air mixture in the combustion chamber of a steam generator when starting, it is necessary to start a pilot burner system based on gas or heating oil.

In order to reduce or eliminate these high-quality primary energy sources for combustion purposes, it is known to operate pilot burner systems with treated pulverized coal. However, this requires considerable technical equipment requirements, since the processed coal dust is obtained either from a separator bunker system or via connecting lines from an operating steam generator.

When using wet coal dust for ignition purposes, it is known to produce a glowing layer of fuel on a grate in the combustion chamber over it to deposit the wet coal dust to dry and ignite. This also requires plant-technical requirements and high expenditures to create the glowing fuel layer.

The attempts to treat moist pulverized coal in a burner in such a way that it should be possible to ignite have not yielded a solution suitable for a realization. The known pilot burner with radial and / or tangential injection of the pulverized coal-air mixture and the secondary air are only reliable when special long-term ignition burners are arranged. In addition, operating currents due to blockages by the coal dust are to be expected.

Furthermore, only a plant-intensive assignment within the plant is possible.

Object of the invention

The aim of the invention is to develop a pilot burner for operation with wet coal dust, which dust up to 25 % with a grain class B should be allowed without a long-term Zündbrenner use.

Explanation of the essence of the invention

The invention has for its object to build a pilot burner so that a preheating of the burner and the pulverized coal and a control of pulverized coal and air flow rate is ensured by a controllable medium. Furthermore, an internal and external recirculation should be achieved in order to achieve a rapid warming of the components of the pilot burner. In addition, a simple plant linkage should be achieved with the pilot burner.

This is achieved in that according to the invention the outlet of the inner tube is connected to a recess forming a recess, known muffle, wherein the recess is formed by an extension of the muffle to the inner tube in the diameter ratio of 1.5 to 2.5, outside the muffle a secondary air supply is arranged and / or that the Ejektorringdüse is connected to a mixing tube.

The further embodiment of the invention is explained in more detail in the exemplary embodiments.

embodiment

In embodiments, the invention is explained in detail. The drawings show in principle:

1: the pulverized coal pilot burner with Ejektorringdüse and muffle, wherein inner tube and muffle form the return stage,

2: the coal dust pilot burner with Ejektorringdüse,

3: the pulverized coal pilot burner according to FIG. 1 with mixing tube and secondary air tubes, FIG.

4: the pulverized coal pilot burner according to FIG. 3 with double wall preheating, FIG.

5: the coal dust pilot burner of FIG. 3 with multiple wall preheating and central tube,

Fig. 6: the pulverized coal pilot burner of FIG. 3 with double Ejektorringduse and mixing tube.

Fig. 1:

The burner consists of the inner tube 4 and the outer tube 3, wherein between the inner and outer tube 4; 3, the insulation 37 is arranged with the inner steam coils 31. The inner tube 4 has the steam-driven ejector 15 with intake pipe 19.

The inner steam coil 31 and the steam-driven ejector 15 are connected via the steam line 8 with shut-off device 9 and the inner ejector 18 with valve 26 to the motive steam network. On the inner and outer tube 4; 3, the muffle 2 is arranged with the recess step 23, wherein the recess step 23 is formed by the extension of the muffle 2 to the inner tube 4 in the diameter ratio of 1.5 - 2.5. At the outlet of the inner tube 4, the tripping edge 22 is provided. The muffle 2 has the cone-shaped

Extension 24 on. In the return stage 23, the igniter opening 39 is arranged *

If the muffle 2 has no heat-storing material, then this is designed as a recirculation tube.

The mode of action is the following:

By opening the throttle device 9 and the valve 26, the inner tube 4 and the ejector 15 is preheated by the superheated steam. At the ejector 15 creates a negative pressure, so that conveying air is sucked. The conveying air is mixed with the emerging from the ejector 15 superheated steam. The conveying air-hot steam mixture generated by the tripping edge 22 and the return step, the vortex 12, so that the muffle 2 is warmed up.

After reaching a specific Vorwärmzustandes the conveying air moist coal dust is added.

The moist pulverized coal suspended in the conveying air is dried up after ejector 15 and preheated. Since the vortex 12 forms in the recess step as a stationary vortex, ignition takes place via the inserted through the opening Gaslunte.

Since the muffle 2 was also warmed up further, a stable initial ignition is formed. By adjusting the throttle device 9 and the valve 26, a control of the pulverized coal flow rate and the amount of steam is achieved.

Fig. 2:

The burner consists of the inner tube 4 and the outer tube 3, the enclosed cavity is filled with insulating material 37 and closed at both ends. Around the Innenrshr 4, the steam coil 31 is arranged with the inlet valve 9. At the outlet of the inner tube 4, the annular tripping edge 22 is arranged. In the inlet of the inner tube 4 opens centrally the intake pipe 19, which has the Ejektroringdüse 15. The Ejektorringdüse 15 has

the steam chamber with the inner pipe 18 and inlet valve 26. To the Ejektorringdüse 15, the annular nozzle 7 with the air chamber and provided on a bolt circle openings 10 is further arranged. The openings 10 can be covered with an adjustable hole circular ring.

The inlet valves 9; 26 are to the steam line 8; 20; connected.

The mode of action is the following:

The pilot burner is taken by opening the inlet and outlet valve 9 in operation, so that steam (300 ⁰ C to 540 ⁰ C at 10 at to 50 at) flows from the steam line 29 through the steam coil 31. As a result, the inner tube 4 is heated. After reaching the required preheating temperature, the Ejektorringdxise 15 is put into operation via the inlet valve 26. The expanding from the Ejektorringdüse 15 steam flows to the wall of the inner tube 4. At the same time from the intake pipe 19, the moist coal dust-air mixture and sucked out of the annular nozzle 7 via the hole circle, air chamber and the openings 10 ambient air. The sucked mixture is also conveyed by the ejector vapor to the wall of the inner tube 4. By steam and preheated pipe wall, a heat transfer to the mixture, so that a drying of the wet coal dust takes place and thus an extremely ignitable mixture is formed

 The annular tripping edge 22 serves to improve the ignition behavior.

In the further embodiment of the invention, it is readily possible to carry out the heating of the inner tube 4 by means of hot air or electrical energy. It is also possible to arrange a further annular nozzle on the intake pipe 19 and to connect the chamber thereof to a line which carries hot air, cold air or low calorific gas.

It is also possible, via the intake pipe 19 tarry moist waste products of gas production and / or wet ash

To promote power plants with or without coal dust. By controlling the motive steam amount via the inlet valves 9; 26; 29, a control of the pulverized coal-air mixture amount and the secondary air amount is achieved, so that the burner power is variable.

3:

This embodiment differs from Fig. 1 such that the steam coil 31 is omitted with steam supply 29 for the inner tube and for the inner tube 4 and outer tube 17, the insulation 37 is housed. On the inner tube 4, the mixing tube 21 is arranged. The D _a mpfkammer 14 with outer steam line 20 is connected directly via the openings 10 with the ejector 15. The central tube 5 with pilot burner 40 is inserted inside or outside of the muffle 2 in the combustion chamber wall 1.

The mode of action is the following:

The commissioning is analogous to Fig. 1, while the superheated steam from the outer steam line 20 via the steam chamber 14, which preheats the mixing tube 21, flows directly to the ejector 15. The intake air sucked in via ejector 15 and mixing tube 21 with D _a mpf heats the inner tube 4 on. The ignition takes place with Gaslunte or pilot burner 40, so that a stable initial ignition is achieved.

Fig. 4;

In the combustion chamber wall 1, the pulverized coal pilot burner is fastened to the outer tube 3, which forms the secondary air supply with the air tube 7.

The secondary air supply is through four at the back. End face arranged air tube 17 is formed, which are connected by means of steam-driven injectors 10 via the inlet 6 with the environment or with the air system.

The injectors 10 are connected via the outer injector 20 with the outer steam chamber, which is formed by the intermediate tube 34 with deflection 35 and by the outer tube 33 and disposed around the outer tube 3. The outer steam chamber has a steam inlet via steam line 8 with shut-off device 9. Steam line 8 and outer injector line 20 are designed as ring lines with corresponding branch lines to the outer steam chamber or to the injectors 10. The air tube 7 forms with the steam jacket tube 16, the inner tube 4 and the deflector 22, a steam chamber with the steam inlet via the stub 14, which can be shut off via the valve 26 from the supply line 25, and the steam outlet via the inner ejector 18. In the back End wall of the inner tube 4 opens centrally the mixing tube 21, which merges into the intake pipe 19 and the ejector 15, which is connected to the inner ejector 18, has. Adjoining the inner tube 4 in the region of the combustion chamber wall 1 is the muffle 2, which forms a return step 23 with the inner tube 4 and forms a conical enlargement 24 for the combustion chamber 1. If the muffle 2 with the conical enlargement 24 does not have any heat-storing material, then this only consists of a recirculation tube in which the recirculation edges 36 are arranged. This construction is possible for certain applications with the same ignition safety and stability.

The mode of action is the following:

When the pilot burner is started up, superheated steam is first conducted via the opening of the valve 26 via the branch lines 14 into the steam chamber. This warms the air tube 7 before and is used at the deflection 35 for preheating the return stage 23. The superheated steam flows along the inner tube 4 in order to also preheat it, and exits the steam chamber via the inner ejector line 18 and enters the ejector 15. From there it enters the mixing chamber.

pipe 21 and generates in A _n suction tube 19 a negative pressure. Thus _n suction pipe 19 conveying air is sucked in from the conveying gas dust line for A, mixed with steam and preheated and injected through the inner tube 4 and the muffle 2 in the combustion chamber. 1

After a sufficient preheating time, the conveying gas dust line is charged with pulverized coal, mixed with conveying air and with the superheated steam from the ejector 15 in the mixing tube 21 and preheated in the inner tube 4, dried and treated ignitable. By means of gas rinsing, pilot burner or electric ignition device, the mixture is ignited in the area of the muffle 2 or combustion chamber inlet. In the return stage 23, a stable hot vortex flow 12 is formed, which secures after ignition from the outside the further initial ignition of the primary mixture conveying air / dust. But it is also possible to arrange the ignition device outside of the muffle 2 and the burner in the combustion chamber wall 1. If the muffle 2 and the vortex flow 12 have warmed up sufficiently, superheated steam from the steam line 8 is introduced via the opening of the shut-off device 9 for further air addition and to increase the discharge rate. The hot steam flows back via the ring and stub lines of the steam line 8 in the outer steam chamber between the outer tube 33 and the intermediate tube along the deflection 35 on the outer tube 3, ¹ warms the outer tube 3 strongly and passes through the ring and stub lines OCE outer injector pipe 20 into the injectors 10 a.

Thus, 6 hot or cold air from the L _u ftsystem or cold air is sucked in from the surroundings optionally depending on the arrangement of the inlet, mixed with the hot steam, is preheated and injected through the tangential arrangement of the air tubes 17 as a swirl flow in the outer tube. 3 After the secondary air outlet from the annular cross-section between the outer tube 4 and the air pipe 7 forms before the muffle 2 a swirl flow, which leads to an inner and outer recirculation and mixing of primary and secondary air, the primary igniter ignition at the return stage 23 the

stable ignition and thus combustion of the mixture in the recirculation zone before the muffle 2 secures.

Fig. 5:

The burner consists of the intake pipe 19, which is connected to the steam-driven ejector 15. This opens in the mixing tube 21, which adjoins the inner tube 4. Adjoining the inner tube 4, in the direction of the combustion chamber 1, is the tripping edge 22 and the muffle 2, which has the recess step 23 and the conical enlargement 24. In the center of the inner tube 4, the central tube 5 is arranged, which is welded tight and provided at its periphery with openings. The central tube is connected to a supply 25 with valve 26 and has on the front side of the trip edge 27. At the outer diameter of the muffle 2, the air supply connects. It consists of an outer tube 3 and an inner air tube 17, both open into the inlet 6 and the air inlet housing 7 and are equipped with guide vanes 11. To the outer tube 3 outer D _a mpfwendeln 28 are wound, which is provided with an outer steam supply 29 and via a connecting line 14 into its central steam coil 30, which is arranged around the inner air pipe 17 opens. An outer ejector line 20 leads to the ejector 15 from the central steam coil 30. An inner steam coil 31 is likewise wound around the inner tube 4, which is connected to the steam line 3 with shut-off device 9 and opens into the ejector 15 via an inner ejector line 18. The ejector 15 with Ejektorleitungen is housed in a housing.

The mode of action is the following:

Before the burner is put into operation, it is preheated. This is done by opening the steam line 8 via the shut-off device 9 and the outer steam supply 29. Thus, steam flows from the steam line 8 to the inner steam coil, thereby heating the inner tube 4.

Via the internal ejector line 18, the steam flows to the ejector 15 as well as from the outer steam feed 29 into the outer steam coil 23, via the connecting line 14 into the middle steam coil, thereby heating the outer tube 3 and the air tube 17. From there, the steam also flows via the outer ejector 20 to the ejector 15,

The exit of the steam from the ejector 15 leads to the intake of conveying air from the intake pipe 19. The vapor-air mixture mixes in the mixing tube 21, enters the preheated inner tube, there is also further preheated, flows around the central tube 5 and flows over the Muffle 2 in the combustion chamber.-At the outlet of the hot mixture from the inner tube 4 is formed by the existing recess step 23 an annular outer vortex flow 12, which is still favored by the trip edge 22. Also formed in the free end wall region of the central tube 5 in front of the tripping edge 27, an annular inner recirculation zone 13. Thereafter, the opening of the valve 26 via the supply line 25 fuel gas is passed into the central tube 5, which enters through the openings 10 in the inner tube and with the mixes hot air-steam mixture and in the region of the inner recirculation zone 13 or Wirbelströmung 12.zündet. The existing there stable gas flame warms up the muffle 2. In the further Anfahrbetreib the sucked on the intake pipe conveying air coal dust is added. The forming in the mixing chamber 20 coal dust-air-steam Geraisch. is further preheated in the hot inner tube 4 and stably ignited by means of the areas of the recirculation zone 13 and vortex flow 12. The recirculation zones 13 and the swirling flow 12 form stable burning coal dust vortices, so that with appropriate coal quality, the fuel gas supply can be throttled via the supply line 25, closed or replaced by steam supply or air supply.

But it is also possible to ignite the coal dust-air-steam mixture by a gas or oil vortex burner, which outside or inside the muffle 2 a pilot flame

or to ignite by electric ignition or heating ~ in the area of the vortex flow 12 and the recirculation zone 13 and thereby to replace the fuel gas supply by the central tube 5. In this case, the central tube 5 can serve for receiving a pilot burner or an ignition device, from the combustion chamber side end face of the central tube 5, the pilot flame or the electric ignition device, the inner recirculation zone 13 stably ignited, Another solution is that the inner ejector 18 not but with the ejector 15 is connected to the supply line 25, so that the superheated steam of the inner steam coil 31 is used to preheat the central tube 5 and via the openings IO for further preheating of the pulverized coal conveying gas-steam mixture is used.

Fig. 6:

In the opening of the combustion chamber wall 1, the air tube 7 is arranged with the conical enlargement. Around the muffle 2, the tube 17 is arranged for the secondary air outlet and equipped with ladder blades 11 for swirl generation. The fingertip secondary air outlet is open to the ambient air. The air pipe 17 are evenly distributed and have the injector 10 with inlet 6. The injectors are connected via the supply line 25 and valve 26 to the steam network. The heat-storing muffle 2 has the conical enlargement 24 and attached to its recess step 23 annular recirculation edges 36. The adjoining the muffle 2 inner tube 4 has the annular tripping edge 22 on. The ratio of the diameter of muffle 2 to inner tube is about 1.5 2.5, so that the recess step 23 is formed. In the inner tube 4, the ejector 15 is centrally integrated, the intake manifold also serves as a mixing tube 21 for the outer ejector 38 arranged in front of it. The outer ejector 38 closes off as an intake pipe 19, which is connected to the delivery line.

Ejector 15 and outer ejector 38 are connected by the shut-off internal ejector 18 and outer ejector 20 via the connecting line 14 to the output of the inner steam coil 31. The steam coil 31 is connected to the steam line 8 with shut-off device. The ejectors 15; 38 and the inner steam coil 31 are arranged in the insulation 37, which is surrounded by the outer tube 3.

The mode of action is the following:

When starting the burner 9 hot steam is passed through the steam line 8 into the inner steam coil 31 and thus preheat the inner tube 4 by opening the shut-off device. The steam enters the outer ejector 38 via the connecting pipe 14 with the inner ejector pipe 18 and the outer ejector pipe 20 open, generates a negative pressure in the intake pipe 19, whereby conveying air from the connected conveying pipe is sucked into the mixing pipe, mixed with steam and preheated from the hot Inner tube 4 flows out. In this case, the return edge 23 in conjunction with the tripping edge 22 leads to an annular stable vortex flow 12. The annular Rezikulationskanten 36 additionally cause small inner recirculation zones 13, so that the muffle 2 is preheated. After a preheating of the conveying air pulverized coal is added, which is dried in the mixing tube 21 and the inner tube 4 and preheated and exits as an ignitable mixture from the inner tube. About a not shown pilot burner, the emerging from the muffle 2 coal dust-air-steam mixture is ignited. Thereafter, at the return stage 23, a stable initial ignition is formed by the vortex flow 12, which is further assisted by recirculation and deposition of glowing dust particles in the inner recirculation zones 13. Thereafter, steam is passed via the line 25 into the injectors 10 via valve 26, sucked through the inlet 6 ambient air and slides through the air tube 17 in the annular secondary air supply, twisted on the guide vanes 11 and the

Burning the residual dust used the primary flame. With further increase in performance of the burner, it is necessary that in addition the ejector 15 is taken in 3betrieb with open inner ejector 18. Thus, the negative pressure in the intake pipe 19 is increased and the promotion of a larger amount of the conveying gas-dust mixture is ensured · About the commissioning of the ejectors 15; 38, in addition to the control of the amount of steam via the throttle devices in the Ejektorleitungen 18; 20 the power of the burner can be controlled in. Wide limits. The same applies to the secondary air quantity, which is sucked in without operation of the injectors 10 via the free rear annular cross section through the negative pressure in the combustion chamber and the amount of which can be considerably increased by the steam control of the injectors 10.

It is also possible, instead of the guide vanes 11, to tangentially engage the air pipes 17 with injectors in order to produce the swirl flow.

The invention achieves the following advantages:

1. The preheating of the burner wall takes place before the ignition burner is put into operation, so that the safe ignition is given immediately at start-up. The preheating is also possible with external steam.

2. By the Ejektoransaugung the coal dust-air mixture this is pressed to the highly preheated burner wall; Thus, a safe ignition of coarse moist lignite coal dust class B with dust moisture to at least 25 % is possible.

3. The Dampfejektorwirkung ensures due to the sufficiently high form a good turbulence of the coal dust air mixture with an improved initial ignition and a high intake to secure the throughput. Here are z. B. through a 10 m long conveyor pipe (100 mm j3) by Selbstansaugung mindestesn 2 t / h coal dust conveyed.

4. By the simultaneous use of preheat steam as ejector steam, the supplied steam heat with a high pre-pressure is fully usable for preheating, suction and atomization simultaneously of air and dust.

5i The only control quantity required for burner operation (throughput of dust and air) is the amount of steam or steam pressure.

6. The formation of inner and outer Rezirkulationsw-irbel a rapid heating of the muffle is guaranteed.

7. A safe and stable initial ignition is achieved.

8. The pulverized coal throughput and the amount of air are controllable,

Claims (25)

invention claim 1. pulverized coal pilot burner with a primary mixture leading intake pipe and then extended inner tube and / or between intake manifold and inner tube disposed Ejektorringdüse, characterized in that the outlet of the inner tube is connected to a recess forming a known muffle, wherein the Rücksprungstufe is formed by an extension of the muffle to the inner tube in the diameter ratio of 1.5 to 2.5, outside the muffle, a secondary air supply is arranged and / or that the Ejektorringdüse is connected to a mixing tube. 2. pilot burner according to item 1, characterized in that the muffle is designed as a recirculation tube · 3. pilot burner according to item 1, characterized in that the steam chamber of the Ejektorringdüse is connected to a controllable motive steam connection. 4. pilot burner according to item 1 and 3, characterized in that the Ejektorringdüse having an air-pressurized annular nozzle. 5. pilot burner according to item 1, characterized in that the inner tube is designed as a double tube and has a steam, hot air or electrically heated heat exchanger. 6. pilot burner according to item 4, characterized in that the annular nozzle is acted upon with fresh air, hot air and / or fuel gas. 7. pilot burner according to item 1, characterized in that the outlet of the inner tube has an annular tripping edge. 8. pilot burner according to item 3, characterized in that the steam-heated heat exchanger is connected in series with the steam chamber of the Ejektorringdüse. 9. pilot burner according to Punkt.1 and 2, characterized in that arranged around the inner tube and / or the muffle secondary air and / or pulverized coal pipes. 10. pilot burner according to item 1, 2 and 9, characterized in that further muffles are arranged at the outlet of the secondary air and / or pulverized coal pipes, wherein secondary air and / or pulverized coal pipes and the further muffles form a recess. 11. pilot burner according to item 1, 2, 7, 9 and 10, characterized in that at the outlet of the inner tube and / or the secondary air and / or pulverized coal tubes a tripping edge and / or a dust body is arranged. 12. pilot burner according to item 1, 2, characterized in that turbocharger rings are arranged in the muffle. 13. pilot burner according to item 1 and 5, characterized in that within the inner tube, a steam, air and / or Brenngasbeaufschleses, provided with openings central tube is arranged. 14. Pilot burner according to item 1 ,. 5 and 9, characterized in that the inner tube or the secondary air and / or pulverized coal pipes have steam or air operated, tangentially arranged ejectors. 15. pilot burner according to item 1, 9 and 10, characterized in that an initial ignition device or a pilot burner is arranged in the return stage. 16. pilot burner according to item 1, 5 and 9, characterized in that the wall of the inner tube and / or the secondary air and / or pulverized coal pipe are designed as steam or air-operated double tubes. 17. pilot burner according to item 1 and 13, characterized in that the combustion chamber facing end side of the inner tube and / or the central tube is provided with heat-storing material. 18. pilot burner according to item 1, characterized in that at the outlet of the mixing tube, a further steam or air operated Ejektorringdüse is arranged. 19. pilot burner according to item 18, characterized in that the Ejektorringdüse is provided with a further mixing tube. 20. pilot burner according to item 5, characterized in that the double tube is provided with a heat insulation or storage. 21. pilot burner according to item 1, 3 and 4, characterized in that, depending on the pressure in the annular nozzle, taken from the pressure or differential pressure in the intake or conveying air line or in the coal discharge device of the steam controlled from the steam network and / or Coal dust controllably fed into the supply line. 22. pilot burner according to item 21, characterized in that in front of the annular nozzle an acted upon by a controller influenced by the pressure, located on the steam network valve is arranged. 23. pilot burner according to item 22, characterized in that measuring points are arranged for the pressure or differential pressure in the steam chamber and / or supply line and / or discharge device. 24. pilot burner according to item 1, characterized in that the pilot burner is used to promote a pulverized coal conveying gas mixture. 25. pilot burner according to item 1 to 21, characterized in that the pilot burner is connected via a conveying gas line with a arranged on a pulverized coal bunker, an annular gap having removal carousel. For this 6 sheets of drawings