DD151993B1 - METHOD AND ARRANGEMENT FOR OPERATING A CARBON STEEL BREAKER - Google Patents

Description

Field of application of the invention

The invention relates to a method and an arrangement for operating a coal dust-fired auxiliary burner for a pulverized coal combustion.

Characteristic of the known technical solutions

For low-oil or -lose starting a pulverized coal for steam generators, it is known

- to win flammable coal dust and thus in the start-up and part-load process to operate backup fire (DD-PS 120533, 141 249,76762,42500,35689, DE-OS 2816733, 2806363, DE-PS 926024, 923213, 746929),

- To operate small oil auxiliary burner and small Kohlenstaubstützbrenner (DD-PS 119461);

- rust-fired support fire to operate (DD-PS 127937).

For the production of an ignitable pulverized coal for the realization of the known solutions are significant expenses in terms of plant and process engineering required and also lead only to satisfactory partial solutions, so far apart from an application. However, since with the increase in power plant performance and the increasingly ballast-rich raw lignite coal heating oil demand has become very large even with low-oil start-up, applicable for existing and new power plants solution is required.

To save support fire in partial load operation, it is known to concentrate the pulverized coal in the main pulverized coal burner (DD-PS 149256; 141249). Although this solution seems promising for partial load operation, however, start-up operation can not be realized in any way.

Are known combined facilities for the promotion and combustion of dust in pulverized coal pilot burners, which suck in additional blower air from the hot air duct and use for promotion (DR-PS 746 929).

However, the blower is not pressure-resistant in explosion-proof Förderleitungsbrennersystemem and is thus destroyed in deflagration.

It is also known to divert a partial flow of the hot gases or hot air to the mill and zuzumischen this Zellradzuteiler coal dust and to promote the burner (DR-PS 923213). Here, too, the explosion safety is not guaranteed in the case of reignition, because a connection line to the pulverized coal leading mill is present.

In all solutions, feeders (e.g., screws and cell wheels) are necessary to shut off the conveyor line to the bunker against air ingress that is severely subject to wear and requires electrical drives.

Furthermore, a pneumatic conveyor is known, which sucks on diffuser means with additional opening for the controlled supply of additional gas from a discharge port of a reservoir powdered to bulk bulk and blowing through a delivery line (DD-PS 65225). However, this solution requires fine-grained non-adhesive, dry bulk and is not suitable for coarse wet coal dust. The necessary small outflow estuaries lead to constipation. The additional opening for additional gas and the small cross-sections to the effectiveness of the diffuser are not suitable for coal dust. This device can also be used only for metering low mass flows, since the diffuser effect and air performance for large delivery pipe diameter can not be realized with this principle of action. Furthermore, the combustion-technically necessary mixture of primary air and dust to the burner is not feasible.

Object of the invention

The aim of the invention is to win a flammable coal dust for combustion in a support burner with simple means and to ensure the operation of the support burner without fuel oil.

Explanation of the essence of the invention

The invention has for its object to directly integrate the extraction of flammable coal dust in the pulverized coal firing and perform the operation of the support burner controllable with the combustible coal dust and to find a to be realized with little effort arrangement.

This is achieved in that according to the invention the pulverized coal with or without conveying gas as a concentrated dust flow by injector effect of pressure and / or hot air to the support burner controllably promoted and / or sucked by injector acting as secondary air pressure and / or hot air controllable in the support burner and as ignitable mixture is injected into the ignition muffle of the support burner. To implement the method according to the invention, the line leading to the support burner injector devices for pressure and / or hot air, the ignition muffle of the support burner is connected to a pressure, hot air and / or steam connection and has a Zündhilfsbrenner on.

embodiment

In one embodiment, the invention is explained in detail. The drawing shows:

Fig. 1: the arrangement in principle

Fig. 2: the efficiency scheme arrangement

In the horizontal part of the dust line 1.1 of the pulverized coal channel 2.1 for the pulverized coal main burner 3, the adjustable separation flap 4 is arranged (FIG. 1). Below the separation flap 4 bunker 5 is arranged with adjustable flap 6 in the output in the coal dust channel 2. Under the bunker slide 6 begins the line 8, which has a not shown air intake to the ambient air and a shut-off compressed air connection 9 in the bunker output. The line 8 opens into the burner head of the pulverized coal support burner 10, wherein the compressed air connection 9 also in the burner head in the annular gap around the mouth of the line 8 binds. The muffle of the pulverized coal support burner 10 is provided with hot and / or compressed air or steam connection 11 and / or Zündölanschluß 12. The filled with flammable coal dust bunker 5 is closed. The flap 6 is closed

 The mode of action is the following:

When starting the pulverized coal firing, first the pulverized coal supporting burner 10 is put into operation. The compressed air is put into operation. When shut off the compressed air connection in the bunker spout all the compressed air reaches the burner head and flows there through the annular gap around the mouth of the line 8 as secondary air in the coal dust support burner 10. In the mouth of the line 8, a negative pressure is generated, which by Injektorwirkung to the primary air flow from the air intake opening in the bunker output area via the line 8 leads to the burner head. However, it is also possible to additionally suck in hot air or pulverized coal via the injector device 7 by the injector effect of the compressed air and to introduce the mixture at the burner head. Now, if the Zündölanschluß 12 is put into operation, ignited the Zündölflamme and simultaneously open the flap 6, flammable coal dust flows into the bunker outlet and is transported by the primary air flow to the burner head, mixed with secondary air and ignited by Zündölflamme.

Depending on the length of the cable and the diameter of the pipe, the amount of compressed air to the burner head can be varied by making it possible to press a part of the compressed air via the adjustable compressed air connection to the bunker outlet, which thus forms part of the primary air and thus less primary air via the air intake opening from the ambient air is sucked. As a result, different amounts of coal and coal qualities can be adapted with their different conveying properties of pipe guides and sizes and the necessary amount of combustion air are provided on the muffle available. In this case, blockages in the line 8 are automatically freed by the suction effect of the burner head. But it is also possible to blow open by opening the compressed air connection 9 to Bunkerausgang the case of too large opening of the flap 6 forming deposits or fillings.

By the coal dust support burner 10, the combustion chamber of the steam generator is warmed up until such an ignition temperature is reached that the blown by the coal dust main burner 3 in the combustion chamber ballast-rich raw lignite ignites.

If this temperature is reached, the pulverized coal from ballast-rich raw lignite coal and the delivery gas via the pulverized coal channel 2 into the vertical dust lines 2.1, via the allocator, chute and pulverized coal mill, not shown, 2.2 and the horizontal dust lines 1.1; 1.2 promoted to the coal dust main burner 3. Due to the ignition temperature reached in the combustion chamber, the coal dust is ignited. As the heating progresses, the mill is put into operation and the separating flap 4 is opened again, so that part of the coal dust conveyed in the dust line 1.1 is precipitated as concentrated dust stream at the separating flap 4 and introduced into the bunker 5. As a result, the bunker 5 is continuously filled with flammable coal dust.

However, it is also possible that the separation flap 4 is already open when starting and filled by the timely start of the mill of the bunker 5 (Fig. 2).

In this case, the pulverized coal channel 2.2 is closed by the flap 36, so that the entire coal dust on the coal dust channel 2.1 and the fully open flap 4 and locked main burner 13 is conveyed with conveying gas through the bunker 5 to 8 line. Thereafter, the pulverized coal supporting burner 10 is ignited. Is in this driving the slide 6 partially opened from the beginning of the starting process, flammable coal dust is sucked with Mühlenfördergas in transit operation by the suction of the secondary air of the burner head via bunker 5 and 8 line, this secondary air replaces the missing primary air quantity from the line 8 and the combustion ensures the dust on the muffle. When sufficient for combustion primary air intake via the line 8 but also the suction on the burner head can be partially or completely done by the steam connection 11, which optionally still preheats the muffle. If the operation of the pulverized coal main burner 3 is stabilized, optionally the carbon dust supporting burner 10 is taken out of operation by hot and compressed air connections 9; 11 taken out of service and the flap 6 is closed. In this case, the separation flap 4 is to be kept open until the bunker 5 is sufficiently filled with flammable coal dust. The realization of the invention in the pulverized coal firing of a steam generator of high power is explained with reference to FIG. 2:

The pulverized coal main burner 3 consists of the dust lines 1.1; 1.2, the partial burners 13.1; 13.2 and the hot air box 14th

In the dust line 1.2, the adjustable separation flap 4 is arranged, which shuts off the dust channel 1.2 partially or completely to the partial burner 13.2, and connected to the bunker 5 hopper 15 incorporated. Zwichen hopper 15 and bunker input is the adjustable flap 16 and the bunker output the adjustable flap 6 is arranged. At the bunker exit, the line 8 provided with the injector device 7, which is connected to the coal dust support burner 10, begins. The hot air duct 17 is connected via the hot air line 18 to the hot air box 14, via the hot air line 19 to the line 8, via the hot air line 20 to the pulverized coal support burner and via the hot air line 21 to the ignition muffle 22. The compressed air network 23 is via the compressed air line 24 to the hot air box 14, via the compressed air line 25 to the line 8, via the compressed air line 26 to the coal dust support burner 10, via the compressed air line 27 to the ignition muffle 22 and the compressed air line 28 with the Zündölbrenner 29th connected.

The Zündmuffel 22 also has the steam connection 30 and the Zündölbrenner 29, the oil port 31. The bunker 5 is connected via the flap-controlled line 37 to the combustion chamber of the flue gas recirculation or the mill chute. The flap 36 optionally closes the dust lines 1.1; 1.2. The mode of action for a first operating case (pressure and suction conveying) is the following:

The mill is taken in cold condition in operation and abandoned a small amount of coal. The flap 36 closes the channel 2.1. The flap 4 closes the channel 1.2 to the partial burner 13.2. The flap 16 is opened at an angle φ. The flap 6 is closed. The bunker is empty. The hot air line 17 is connected to the neighboring steam generator. The steam line 30 and the hot air and compressed air lines 21; 18 and 27; 24 are put into operation. Via the compressed air 23 hot air is thus sucked from the hot air duct 17 and the hot air box 14 and the Zündmuffel preheated with simultaneous external steam supply 30. The throttling of the conveying volume of the mill by closing the channel 2.1 via the flap 36 in conjunction with the small amount of coal in the mill for the preparation of finely ground ignitable dust, which over the channel 1.2 and di <? Absch'eideklappe 4 iri the bunker 5 is stored. After separation of the dust in the bunker 5, the conveying gas is sucked back via the line 37 to the flue gas recirculation. After a short period of operation for partial filling of the bunker 5 together or optionally the hot air and compressed air lines 19; 20 and 25; 26 put into operation, the flap 6 is opened, promoted via the line 8 ignitable dust to the burner 10, the line 28 and 31 put into operation and the oil pilot burner 29 ignited. Immediately thereafter, the hot air-dust mixture ignites the burner 10 and the lines 28 and 31 are closed again. After preheating the combustion chamber, the coal addition is increased to the mill, the flap 36 is vertical and about both coal dust pipes 1.1; 1.2 the coal dust to the partial burners 13.1; 13.2 promoted and ignited by means of the pulverized coal support burner 10. If the operation of the support burner 10 is not necessary in continuous operation, the bunker 5 is driven empty and all switched on startup hot and compressed air lines 18; 19; 20; 21; 24; 25; 26; 27; 28 and the separating flap 4 and the flaps 6; 16 are closed. In the other case, the open flaps 6; 16 and separation flap 4 a continuous coal flow to the support burner to support the main burner and also with open lines 28; 31 a continuous flame of oil to support the pulverized coal support burner in operation and the hot air duct 17 connected to the hot air duct of its own steam generator.

In this mode of operation with simultaneous air supply, the promotion of the dust from the bunker 5 to the burner 1OaIs combined pressure-suction promotion will be done. By supplying a mixture of hot and compressed air via the lines 20; 26, wherein the compressed air 26 sucks the hot air 20 via an injector, an annular air flow is injected at the burner head over the junction of the line 8 under pressure, which generates a relative negative pressure in the line 8 and thus the Ansaugender the hot and compressed air 19; 25 with the added coal dust from the bunker. In this case, the hot air 19 is sucked in and mixed in via the injector device 7 via the compressed air 25. Depending on the proportion of individual air volumes 19; 20 and 25; 26 can optionally outweigh suction or pressure promotion and thus eliminates blockages or dust loads or the amount of subsidized dust can be controlled. It is possible, the difference in amount of air to the entire necessary for combustion on the burner air via the lines 21; 27 to admit to preheat in the ignition muffle 22 and gradually allocate along the combustion path in the area of the ignition muffle. The combined pressure-suction can be used in optional operation of the lines 25; 19; 20 and / or 26 lead to different mixing conditions between the fuel dust and air and thus conveying and burning behavior depending on the fuel dust quality at the burner muffle.

The mode of action for a second operating case (pressure delivery) is the following:

Before starting the pulverized coal pilot burner 10, the bunker 5 is filled with dust. Thereafter, the compressed air line 25 is put into operation and the flap 6 is opened. The pulverized coal falls into the injector 7 and is there flushed by the pressing pressure of the injector directly into the conical constriction and promoted via the cross-section same line 8 with minimum amounts of air to the burner 10. At the same time, the double wall of the ignition muffle 22 is flushed with secondary air via the compressed air line 27 and this is added stepwise along the combustion path in the ignition muffle 22.

The ignition of the mixture takes place in the ignition muffle 22 via suitable ignition devices by means of oil, gas or electric. The heat generated by combustion in the ignition muffle 22 leads to the heating of the inner double wall and thus to the preheating of the gradually added secondary air.

The promotion by means of pure compressed air ensures z. B. a high dust density in the primary air of z. B. 6-10 KgSt / kg air with only small amounts of air flow per burner power.

For small burner outputs after commissioning of the mill and the suction of conveying gas-dust mixture by means of the sucking line 37, which z. B. is involved in the flue gas recirculation before mill, deposited by suitable separation devices in the bunker 5 or an intermediate cyclone so much dust at the same time in the bunker 5 that the pulverized coal pilot burner 10 can be operated stably even in the starting operation of the mill with coal dust.

Of course, this variant also with additional air intake from the hot air duct 17 or from the environment by the injector effect of the compressed air 25; 27 via additional lines 19; 24 are operated. In this case, the line 8 is to be enlarged and the injector installed on the air intake side before coal.

In this case, increased demands on the inflow of a limited amount of coal over flap 6 to prevent spilling of the bunker outlet.

But it is also possible that at sufficiently high pressure of hot or cold air from the line 19, the pulverized coal is conveyed in the line 8 and only in blockages in bunker discharge or line 8, the compressed air 25 is taken to blow-up discontinuously into operation.

The invention provides the following advantages:

1. Using compressed air, the promotion of dust can be done at low air volumes; Compressing energy is saved.

2. The amount of pulverized coal to the burner can be controlled via the controllable air volume and thus the burner output.

3. By placing the compressed air injector directly in the bunker or in the extraction device behind the bunker dust from the storage state can be pressed by the pressing pressure of the injector directly into the line to the burner. In this case, optimal ratios of primary air and dust are achieved for the ignition and the metering device including drive is saved.

4. When operating pure compressed air without hot air and arrangement of the injector 7 in the bunker or bunker outlet, the conical constriction is used only for flushing the dust by means of compressed air. This leads to considerable simplifications of the wiring and cost savings, especially in pressure-resistant versions.

5. Is charged via compressed air of the burner with low-air dust-air mixture, the second compressed air can be introduced to the burner 10 via line 27 into the ignition muffle 22. In this case, the compressed air in the ignition muffle 22 can be warmed up by the combustion in the enclosed ignition combustion chamber and added metered via a plurality of outflow openings 27 into the ignition combustion chamber along the combustion path. This ensures that along the combustion path only as much preheated air is supplied, as is necessary for local combustion, and there are thereby maximum combustion temperatures.

Claims (13)

Invention claim: 1. A method for operating a coal dust-fired auxiliary burner for a pulverized coal, wherein from the coal dust duct coal dust deposited, promoted and / or bunkered and fed to the support burner, characterized in that the coal dust with or without carrier gas as a concentrated dust stream by injector effect of pressure and / or Hot air to the support burner controlled promoted and / or controlled by injector acting as secondary air pressure and / or hot air controllable sucked into the support burner and is blown as an ignitable mixture in the ignition muffle of the support burner. 2. The method according to item 1, characterized in that hot air is introduced as an additional medium in the ignition muffle of the support burner. 3. The method according to item 1 and 2, characterized in that the hot air is sucked by injector from an operating steam generator. 4. The method according to item 1 and 2, characterized in that the hot air is sucked by injector action from the own continuous steam generator. 5. The method according to item 1, characterized in that pressurized and / or hot air is introduced as primary air for the pilot burner. 6. The method according to item 1 to 4, characterized in that the hot air is introduced for preheating the pulverized coal burner, the support burner, the combustion chamber and / or the conveyor system for the combustible pulverized coal. 7. The method according to item 1, characterized in that the conveying gas is conveyed after deposition of the coal dust in the furnace, in the flue gas recirculation or in the mill chute. 8. The method according to item!, Characterized in that the pulverized coal is removed as a concentrated dust flow by gravity from a dust line of the coal dust duct controlled directly in front of a Kohlenstaubrenner. 9. Arrangement for carrying out the method, wherein a feed line is integrated in a pulverized coal channel and connected via a line to the support burner, characterized in that the line has injector devices for pressurized and / or hot air and that the ignition muffle of the support burner is connected to a pressure , Hot and / or steam connection is connected and / or has a Zündhilfsbrenner. 10. Arrangement according to item 9, characterized in that the input of the delivery line has a further arranged in the dust line of a coal dust channel adjustable flap. 11. Arrangement according to item 9 and 10, characterized in that the delivery line is designed as a bunker. 12. Arrangement according to item 9 to 11, characterized in that the delivery line is connected in whole or in part to the coal dust duct and the burner air box of the pulverized coal burner. 13. Arrangement according to item 9 to 12, characterized in that the delivery line is connected via a flap or slide-controlled line with the combustion chamber, the flue gas recirculation or the mill shaft shaft. For this 2 pages drawings