DD285674A7 - ARRANGEMENT FOR OPERATING A CARVED CARBON FAN VALVE - Google Patents

Abstract

The invention relates to an arrangement for operating a pulverized coal fan for the pulverized coal of a steam boiler. In this case, openings for integrating conveyor channels are arranged in the outflow section of the channels and / or in a transition section arranged after outflow section and / or in the stripping section of the transition section. Fig. 2 {pulverized coal firing; Fan mill; Business; Coal dust Foerdergas mixture; feeders; visually unattractive gas}

Description

Field of application of the invention

The invention relates to an arrangement for operating a pulverized coal fan mill for the pulverized coal of a steam boiler.

Characteristic of the known state of the art

With increasing water and ballast content in the raw lignite coal, serious consequences occur in the ignition and combustion in the pulverized coal of a steam boiler.

It is therefore a variety of solutions have become known to separate the resulting after the pulverized coal mill exhaust gas fine dust mixture small load and / or the exhaust gas fine dust mixture high load from coal dust conveying gas mixture within the classifier or thereafter. The separated mixture is put to particular uses, e.g. Brüdenbrenner (DD-PS 57276), Brüdengasableitung for condensation (DD-PS 243972), Brüdengaseinleitung in the combustion chamber or Nachschaltheizflächen (DD-PS 243329, DD-PS 251 604, DD-PS 262147).

Zündstaubgewinnung for pulverized coal pilot burner, extraction of ignitable coal dust for auxiliary burner (DD-PS 209343,229043), Brüdengas Sichterumgehung (DE-AS 122108, 1208158).

The disadvantages of these separation technologies within the classifier is that the classifier is interpreted according to the total Nachmühlengasstrom, high wear of the classifier installations occurs, special separation internals in the classifier are required by these internals another pressure loss occurs, for the removal of the separated gas quantities a drive is necessary, through the additional installations of the visual process is disturbed and a clear separation of the laden with particulate gas vapor from the coarse grain, in particular ballast shares, is not possible. Due to the Brüdengas-conveying gas-pulverized coal mixture within the classifier therefore considerable expenses for a vapor gas separation are required.

For these reasons, attempts have been made to carry out a separation of the vapor gases within the mill (DD-PS 245 369, 63957.57 276). By dissipating a large proportion of hot gas, dust drying within the mill is substantially reduced. In addition, increases with increasing gap width by Eckpanzerverschleiß the fine dust discharge; In addition, coarse dust is also discharged.

Object of the invention

The aim of the invention is to improve the grinding, visual and / or Feuerungsprozeß with little effort.

Explanation of the essence of the invention

The invention is based on the object by constructive measures conveying gas and / or dust immediately after beating by utilizing high flow rate and to use for effective fire control and for optimal operation of the pulverized coal fan mill.

This is achieved in that according to the invention in the discharge part of the mill and / or arranged in a arranged after discharge part transition part and / or in the discharge part of the transition part openings for the integration of delivery channels.

embodiment

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

1 shows the representation of the pulverized coal conveying gas mixture profile in the outflow cross section of the mill;

FIG. 2 shows the integration of conveying gas ducts over suction cross sections arranged in the transition part; FIG.

Figure 3: the integration of conveying gas ducts for pulverized coal main and support burner in the transition part;

4: the integration of conveying gas ducts for pulverized coal main and -Brüdenbrenner in the Ausströmquerschnitt the

Mill;

Fig. 5: the integration of the controlled conveyor gas channel in the transition part;

Fig. 6: the front view of Fig. 5;

Fig. 7; the integration of conveyor ducts for pulverized coal main, support and ignition burners;

FIG. 8 shows the integration of conveying gas channels into the transition part for forming a multi-chamber separator; FIG.

Fig.9: the side view of Figure 8;

Fig. 10: the separation of sight-worthy cold and hot gas in the transition part to mill;

Fig. 11: the integration of the hot gas channel in the transition part.

In order to separately suck gas with a high and / or low particulate matter from an unspecified or known pulverized coal conveying gas mixture from the discharge part of the mill, the outflow part of the mill and / or a transition part arranged after outflow part and / or in the outflow part of the transition part Variable height openings for opening height dependent dust loading, e.g. B. formed as longitudinal and / or transverse slots arranged. In this case, along the flow path is increasingly forming turbulence flow with fine dust diffusion in the edge region of the flow only with sufficient flow path effective and thus for the extraction of larger amounts of fine dust on sufficient height of openings available.

In this case, depending on the required amount of extracted gas and particulate matter, the width of the longitudinal slot to increase the opening to the square shape can be arbitrarily increased. At low height of the openings, however, low-dust conveying gas is sucked.

This effect can be enhanced by changes in the mill construction reinforced coal dust conveying gas profiles are produced in the outlet section of the mill and / or existing coal dust conveying gas and / or temperature profiles are known in Ausströmquerschnitt and used for the targeted arrangement of the openings. The coal dust fan mill 2 has the Schlagradnabe 83, the incident slope 84, the impact wheel 87, the mill housing 88, the motor-side side wall 78, the mill door side wall 79 and the spiral outer wall 82, the Ausströmquerschnitt 80 and arranged at Ausströmquerschnitt 80 transition part 3, as Diffuser is formed on (Fig. 1). Between the side surfaces of the impact wheel 87 and the side walls of the mill housing 88 and between the outer diameter of the striking wheel 87 and the spiral inner wall 86 and the spiral outer wall 82, the distance 90 is provided in each case. The transition part 3 has the outflow cross section 81.

The mode of action is the following:

During operation of the mill 2, flue gas 27 is sucked axially by the impact wheel 87 and conveyed via the outflow cross section 80 into the transition part 3. At the same time reaches 27 with the flue gas raw lignite 49 in the beater wheel, there is ground in the mill housing 88 and 87 impact wheel and conveyed off as coal dust conveying gas mixture 25 via the outflow 80.

The profile of the pulverized coal conveying gas mixture 25 and the dust distribution at the outflow cross section 80 is controlled by the following measures:

1. on the arrangement of the slope of the incidence 84 of the mill door and the associated influence of the discharge line 85 of the coal 49 in the region of the impact wheel 87;

2. on the formation of the Schlagradnabe 83 by controlling the mill flow 89 within the striking wheel 87;

3. About the diameter, the number and the height of the impact plates of the impact wheel 87;

4. over the distance 90 between the side surfaces of the Schiagrades 87 and the side walls 78; 79 of the mill housing 88 or between the outer diameter of the striking wheel 87 and the spiral inner wall 86 and the spiral outer wall 82nd

Due to the design, arrangement and design of these elements, the dust distribution and the gas flow 89 can be influenced and a profile for the pulverized coal conveying gas mixture at the outflow 80 are generated.

In particular, the distance 90 influences the edge flow of the pulverized coal conveying gas mixture.

For a given distance 90, the profile of the coal dust conveying gas mixture is shown:

The loading "b" (amount of dust / amount of gas) concentrates in the area of the spiral outer wall 82 and the motor-side side wall 78. The loading "b" is a minimum in the region of the Ausströmquerschnittes 80 on the spiral inner wall 86 and the mill door-side side wall 79. The gas velocity "V" of the pulverized coal conveying gas mixture has its maximum in the region of the outflow cross section 80 at the spiral inner wall 86 and at the mill door side wall 79. The same applies to the temperature distribution "T" of the conveying gas.

The described distribution is influenced by the arrangement of the designed as a diffuser transition part 3. If the diffuser of the transition part 3 has a corresponding slope and corresponding diffuser length "L", segregation occurs in the edge region, which causes fine dust to diffuse into the wall region of the diffuser bevel due to turbulence flows 77, while the coarse dust precipitates the flow of pulverized coal. In this way, a relative concentration of fine dust in the diffuser wall region over the outflow cross section 81 for the dust D ₀₀ 63 (passage through the sieve with the mesh size 0.063 mm) results at the outflow cross section 81 in the region of the exit of the transition part 3.

The mill 2 has the transition part 3 and the subsequent classifier 1 (FIG. 2). The vapor channel 61 is arranged over the high narrow Absaugequerschnitt 95 as Brüdenabsaugequerschnitt 91. The channel 21 is integrated via the Brüdenabsaugequerschnitt 91 with the low wide Absaugequerschnitt 94.

The mode of action is the following:

If the mill is charged with a stream of flue gas via the flue gas return duct 4 and with raw lignite, a flow formed from pulverized coal conveying gas mixture 25 forms at the outflow cross section 80 of the mill 2. About the Brüdenkanal 61 low-dust, but gas-rich mixture should be sucked. This is achieved by the arrangement of a Brüdenabsaugequerschnittes 91 in the low-dust flow on the spiral inner wall 86 and the mill door side wall 79 by placing a narrow, relatively high Absaugequerschnittes 95. Thus, a relatively large Absaugequerschnitt 91 is realized in the low-dust mixture. Although relatively high particulate matter enters the vapor channel 61 due to the very high arrangement of the cross section over the turbulence flow 77 with fine dust diffusion, this is not achieved by the arrangement of the suction cross section 91 in the region of the low-dust flow. If, on the other hand, vapor gas in the region of the gas-rich mixture flow is to be sucked out of the area of the spiral outer wall 82 or the motor-side side wall 78, then this vapor suction cross-section 91 must be designed as a low, wide suction cross-section 94. Here, despite the same cross-section 91 relatively low-dust mixture can be sucked off, because the turbulence flow 77 is formed only above the flow path and due to the small height of the cross-section, this particulate matter diffusion in the cross section 94 does not apply. For this reason, a relatively low-dust mixture of the flow of the gas 24 will follow in the channel 21.

The Absaugequerschnitt is high as a narrow cross-section 95 and low wide cross-section 94 in the region of the transition part 3 for dimensioning the Feinststaubanteils or the total dust content of the over the flow of the gas 13; 24 sucked conveyor dust gas mixtures arranged.

The main burner-Zündstaubbrenner system comprises the mill 2 with transition part 3 and classifier 1 (Fig. 3). The sifter 1 is followed by the coal dust channel 5 and the main burner 64. At the transition part 3, the diffuser-shaped extension is arranged, which opens via the outflow cross section 81 in the Zündstaubkanal 17 and the pilot burner 22.

The mode of action is the following:

During operation of the mill 2 and charging with lignite coal via the flue gas return duct 4, a conveying gas dust profile is formed in the region of the outflow cross section 80, which is enriched with dust in the region of the spiral outer wall 82. The flow of pulverized coal conveying gas mixture 25 will flow predominantly into the classifier 1. Due to the diffuser-like widening of the transition part 3, a turbulence flow 77 with fine dust diffusion forms in the region of the high narrow cross-section 95 in the diffuser region. Thus, fine dust is directed into the diffuser cross section 81 formed by the diffuser. The high concentration of pulverized coal in the area of the spiral outer wall 82 is used to draw off relatively much ultrafine dust into the outflow cross section 81 via the turbulence flow 77 and the diffuser formation via the gas flow 24 and to direct it to the pilot burner 22 via the ignition dust channel 17. The relative use of the exit velocities from the outflow cross section 80 of the mill 2 is hereby used to overcome even in the area of the pilot burner 22 even higher pressure losses due to the arrangement of spin bodies 96. These swirl bodies 96 or unverdrallte inner obstructions bring a high pressure drop, but lead to a relatively good turbulence in the region of the pilot burner 22 and thus to a flammable coal dust flame. The majority of the flow of pulverized coal conveying gas mixture 25 passes through the classifier 1 and the pulverized coal channel 5 to the main burner 64. The dust concentration on the flow of the gas 24 is further increased by the fact that a high narrow Absaugequerschnitt 95 is realized, but which its arrangement in the vicinity of the mill door-side side wall 79 of coarse dust is kept free. The coarse dust concentrates primarily on the engine side sidewall 78. The separate support burner operation of the support and / or pilot burner 22 (Fig. 3) is accomplished as follows: Closing the damper 97 will result in minimal coal feed through the circuit separator mill sifter over-pulverized pulverized coal conveying gas mixture over the channel 17 to the ignition and / or support burner when main burner 64 is out of operation drove.

Of course, such a support operation via channels, which bypass the classifier as bypasses, with closed Sichteraustritt done directly on the main burner, with parts of the main burner can also be shut off. The combined main burner-Brüdenbrenner system has the mill 2 with flue gas return duct 4 with the Ansaugequerschnitt (hatched) and the Ausströmquerschnitt 80 of the mill 2 (Figure 4b). The outflow section 80 is divided into the vapor suction section 91, which is e.g. is arranged as a triangle in the area of the mill door side wall 79 and spiral inner wall 86, and the Sichtstaubquerschnitt 92. The Sichtstaubquerschnitt 92 opens into the transition part 3, to which the separator 1 is connected.

In the classifier, the pulverized coal channel 5 is arranged with the main burners 64. The Brüdenabsaugequerschnitt 91 is connected to the vapor channel 91 and the vapor burner 63.

The entire outflow cross section 80 of the mill 2 opens into the transition part 3 (Figure 4a). At the spiral inside diffuser extension of the transition part 3 is in the area of the mill door of the flat Brüdenabsaugequerschnitt 91, which merges on the mill door side of the transition part 3 in the further Brüdenabsaugequerschnitt 91. At these slit-shaped lateral Brüdenabsaugequerschnitte 91 of the vapor channel 61 with a rectangular cross section (shown hatched) is involved, and this goes above the classifier 1 in a rectangular cross-section over.

The mode of action is the following:

During operation of the fan mill 2 and entry of flue gas 27 via the flue gas recirculation 4 into the mill 2, a conveying gas mixture 25 is conveyed through the outflow cross section 80, which analogously to the dust profile "b" in FIG. 1 in the region of the cross section 91 characterizes relatively low dust with high outflow velocities 4b), while dust-rich mixture with relatively low discharge velocities is present in the dust section cross section 92. This conveying dust mixture with relatively much dust and relatively little transport gas is conveyed via the transition part 3 into the classifier 1, sighted there and grit over the semolina return channel 93 of FIG Mill 2 is fed back, while the sighted conveying gas-dust mixture is fed through the coal dust channel 5 to the main burner 54 as a dust-rich, ignitable mixture .. The low-dust mixture as the vapor mixture passes through the Brüdenabsaugequerschnitt 91 and the vapor channel 61 to Brüdenbre men 63 and relieved on the gas side significantly the classifier 1 and thereby increases the ignition stability of the main burner 64 by deducting a significant amount of conveying gas. The high exit speeds in the cross section 91 are used to make the vapor channel 61 can be relatively long, so that at a location of the vapor burner 63, which is located above the main burner 64, the low-dust vapor mixtures injected there do not interfere with the ignition of the main burner.

The additional pressure gain through the high exit velocities in the cross section 91 is used to conduct the vapor mixture (Fig. 4d) in the separator 35, derive the separated particulate matter via the line 39 and z. B. a dust finger of the main burner 64, while the exhaust gas is passed through the Brüdenbrenner 63 or an opening in the combustion chamber or in the Nachschaltheizflächen of the boiler.

However, it is also possible to reintroduce the vapor channel 61 (FIG. 4c) into the main burner 64 or into the pulverized coal channel 5, thereby producing a normal dust mixture. This results in the advantage that a considerable amount of gas has been carried away over the cross section 91 and has bypassed the classifier as a bypass. Thus, the classifier on the discharge side can be relieved and a lower pressure build-up in the classifier will be required. This leads to an increase in the conveying gas dust flow rate of the mill, without the temperature drops to mill.

By lateral extraction of the vapor mixture from the cross section 91, the further separation of dust and gas is promoted (Fig. 4 a). Due to the deflection of the gas, a selection can additionally be achieved here, so that the vapor channel 61 is relieved of further fine dust particles. This is achieved in particular by the fact that the Brüdenabsaugequerschnitt is arranged in the region of the diffuser-side slope and in the area of the mill door diffuser wall as a low, but wide slot, so that a forming during overflow turbulence quickly breaks off again and the dust particles of the Umlenkströmung can not follow. When the slide 97 is closed, the conveying gas volume and the coal feed for the mill 2 are severely throttled and the majority of the grinding material of the mill is repeatedly circulated via the semolina return passage 93 and thus very finely ground (FIG. 4f). Fine-ground highly concentrated pulverized coal conveying gas mixture with excellent ignition behavior is blown into the burner 63 via the vapor channel 61 and vapor burner 63.

This can be ignited with oil burners or other ignition devices in the cold combustion chamber and used to start the steam boiler or used as a flame-retardant support flame for partial load, holding mode and peak load.

Of course, the separator 35 is switchable as Sichterbypaß. In this solution, the vapor channel 61 is passed completely into the separator 35 and its exhaust gases in the pulverized coal pipe 5 or in the burner 64 derived (Fig.4e). Thus, the separator is operated by the pressure gain of the vapor line 61 against the pressure loss of the main flow over classifier 1.

In this case, the separated in the separator 35 fine dust can optionally bunkered for starting and supports or passed directly via Zündstaubleitungen to a support or pilot burner and burned to ignition stable.

But it is also possible (Fig.4e) to introduce the exhaust gases of the separator in a Nachschaltheizfläche, in the combustion chamber or in the flue gas duct until before induced draft.

The solutions provide the following benefits:

1. The high outlet energies and speeds at the mill outlet in conjunction with little dust are used to exclude low-dust gas components from the sighting and to relieve the sifter.

2. The system requires less pressure loss and thus increases mill performance.

3. The sifter can be made smaller, the wear in the sifter sinks, and the separation efficiency of the sifter increases.

4. It can be driven without being seen.

5. Without additional separation units, such. As cyclones, the classification of a pilot burner with dust accumulation is possible.

6. Wear-intensive sealing measures in the mill housing between the impact wheel and mill housing can be omitted. Elaborate fitting work of the coal incidence slope or the mill hub to equalize the dust profile over the discharge cross section can be omitted.

7. The mill can additionally be operated with limestone.

8. Brüdenbrennerkanäle and Zündstaubbrennkananäle and the bypass channels of the classifier can be arranged on existing systems without much effort.

In the transition part 3 of the hot gas duct 7 is incorporated as part of the classifier 1 (Fig. 5 and 6). The hot gas duct 7 is formed by the guide plate 66, which is arranged from the top of the classifier 1 via the stuffing box 67 with the drive 68 height adjustable within the classifier 1. The guide plate 66 is arranged at a distance χ = 0.2 to 0.5 (width of the classifier 1) from the side wall of the classifier 1 (Figure 6).

In the hot gas duct 7 of the provided with the adjustable flap 69 with drive 73 channel 62 is included. The flap 69 is dimensioned so that closed in the position "a" of the channel 62 and in the position "b" at an angle of z.Z. 60 °, the channel 62 is open. In the transition part 3, the stator 71 is arranged with drive 74 in front of the gap formed by the guide plate 66 opening 70.

The mode of action is the following:

The Nachmühlengas 58 with coal dust 4 to mill 2 with the pulverized coal concentration 75 on the rear wall 72 of the classifier 1 flows through vorhmaasübergangsteil 3. According to the design of the transition part 3, the dust-free edge flow 76 forms. About the drive 68, the guide plate 66 is adjusted or sunk into the transition part 3, that the desired gap opening 70 between guide plate 66 and wall 8 of the transition part 3 is reached. During this adjustment phase, the flap 69 in the sifter 1 in position "a" and thus closes the channel 61. After the gap adjustment, the flap 69 is brought into position "b". The flap 69 lies at an angle of e.g. 60 ° on the guide plate 66 at. In order to regulate the dust loading, it is possible, optionally, to adjust the gap opening 70 once and / or to direct the stator 71 from the post-mill medium flow coarse grain 59 in the direction of the gap opening 70. With this arrangement, it is possible to discharge fuel dust in the desired load via the channel 62 according to the requirements.

This achieves the following advantages:

1. No removal of fine dust of the main burner by direct gas separation (or dust) to mill. The sifter effect for Feinstauberhöhung remains intact.

2. Low operating costs.

3. The sifter volume remains unaffected.

4. Simple and retrofitting possible.

5. Control of dust loading.

6. Low wear on the guide plate, as the flow to the lower edge takes place.

7. Avoidance of Sichterquerströmung.

Into the transition part 3 are at an angle of e.g. 10 to 15 ° of the cold gas duct 6 and the hot gas duct 17 incorporated (Fig. 7). The hot gas duct 17 has the flap 26 and is connected via the channel 61 to the burner 63 in the burner level II.

The cold gas duct 6 has the flap 26 and is connected via the channel 62 with the vapor burner 22 in the burner level III. The pulverized coal channel 5 is connected to the main cole dust burner 64 in the burner level I.

The mode of action is the following:

From the mill 2 4 flue gas 27 is sucked from the combustion chamber 40 of the boiler via the flue gas return duct. With the coal 49, which is processed and ground in the mill 2, the Nachmühlengas 58 passes into the transition part 3. The coal dust exiting at high speed with Nachmühlengas 58, in particular the mass-afflicted sand and the coarse grain 59, enters the sifter. 1 The cold gas 24.1 and the hot gas 13 passes as a fine dust mixture in the cold and hot gas duct 6; 17. With the arrangement of the bevels on the transition part 13 little coarse dust enters the channels 6; 17, because the high-velocity carbon dust particles are not deflected laterally. In the channel 61 mainly Nachmühlen-hot gas 13 is directed with strongly dried fine dust 46 and the burner level Il fed through the flap 26. With the arrangement and design of the burner 63 and the dust treatment is a short, hot flame 65th

achieved that heats up in particular the sucked-back flue gases 27 and supports the combustion and the flame formation of the burner level I. On the drive side of the mills 2 is deducted via the slope of the transition part 3 and cold gas duct 6, due to the different coal loading on the Schlagradbreite, gas 24.1 as a relatively cold Nachmühlenteilgas. This gas 24.1 with low dust load passes through the channel 62 below the integration of the flue gas return duct 4 into the combustion chamber 40 in the Brüdenbrenner 22 of the burner level III. The afterburner gas 58 heavily laden with pulverized coal, reduced by the amounts of gases 13; 24.1, enters the relatively small, specially armored classifier 1 and after sighting via the pulverized coal pipe 5 into the pulverized coal main burners 64 of the burner level I. To this burner 64 a lot of dust, e.g. 80% of the total amount of dust after mill 2.

This achieves the following advantages:

1. Increase of the conveying gas quantity of the mill by changing the throttle characteristic.

2. Increase the post-mill temperature or the raw lignite throughput even with increasing ballast content.

3. Improvement of Staubauftrocknung.

4. Small sifter - low construction volume.

5. Distribution of the dust load in wear-intensive and low-wear parts.

6. Reduction of the dust channel cross sections.

In the transition part 3 (Figures 8 and 9) are on the openings 8; 9 of the partial chamber acting cold gas duct 6 and the hot gas duct 17 integrated and form with the classifier 1 the Mehrkammersichter. In the openings 8; 9 are the adjustment flaps 50; 51 arranged. Within the channels 6; 17 are the adjustable viewing elements 52; 53 arranged. The sifter 1 has the semolina return funnel 54 and the semolina return passage 55. The channels 6; 17 also have the other semolina recycling funnels 56 and semolina recycling channels 57.

The mode of action is the following:

In the mill 2 reach the flue gas 27 and the coal49. The Nachmühlengas 58 as coal dust-flue gas-vapor mixture is passed into the transition part 3. About the controllable adjustment flaps 50; 51 is immediately after mill 1 a low-dust gas-dust mixture 13; 24.1 deflected and acting in the part chamber view channels 6; 17 dissipated. The adjustment flaps 50; 51 are dimensioned so that they form an extension of the sifter intermediate wall in the vertical position and are at the center of the slope of the transition part 3 at the end. In the closed position are the adjustment flaps 50; 51 at the slopes of the transition part 3 and thus close the flow cross-section to the cold or hot gas ducts 6; 17th

In maximum open position, the adjustment flaps 50 extend; 51 to the vertical of the outlet cross-section of the mill 1. About the so adjustable flaps 50; 51 is at the respective mill side, the hot gas 13 and cold gas 24.1 in the channels 17; 6 steered.

According to the desired degree of dust, the classifier elements 52; 53 regulated.

The separated coarse grain 59 of the channels 6; 17 passes over the semolina recycling funnels and channels 56; 57 in the semolina recycling funnel 54 of the classifier 1. With the partial gas part chamber direction the Nachmühlengas 58 is divided so that a large proportion of gas from z. B. 40% of the amount of visible gas as partial gas 13; 24.1 into the channels 6; 17 is flowing. The residual gas with a lot of dust, z. B.

80% of the total dust load, flows through the classifier 1, which is provided according to the high dust load with reinforced Sichteinbauten.

The separated coarse grain 59 from the channels 6; 17 is passed via Grießrückführkanal 57 directly into the flue gas return duct 4 or in the semolina return funnel 54 or semolina return passage 55.

With this arrangement of the partial gas distribution in a multi-chamber separator, the pressure drop over the classifier is substantially reduced, with the semisolid gas flow through the recirculations into the classifier 1 being very low.

This achieves the following advantages:

1. Reduction of the pressure loss of the grinding plant.

2. Small classifier training.

3. Grain sighting with high dust load, improved grinding fineness.

4. According to intended use individually adjustable chamber views.

5. Subsequent installation at low cost.

6. Increase of the raw lignite throughput also with increasing ash content of the raw lignite coal.

7. Treatment of low calorific value fuels.

The integration of the cold gas duct 6 into the transition part 3 (FIG. 10) adjoins the deflector 19 arranged in the exit region 12 of the mill 2.

The mode of action is the following:

Immediately from the transition part 3 to exit area 12 of the mill 2 is discharged from the amount of total gas 23, a weakly loaded with dust amount of cold gas 24.1 through the openings 20 and cold gas channels 6.

This gas 24.1 has only a very low proportion of coarse dust. Due to the sampling point, this dust partial gas quantity is no longer required. With the supply of this amount of gas 24.1 in the pulverized coal conveying gas mixture 25 by classifier 1 or optionally in the Brüdenbrenner 22 of the classifier 1 is relieved by this amount of gas.

The pressure difference across the classifier 1 determines the gases 24.1 which have been sucked off or short-circuited outside the classifier. The discharged gases 24.1 are increased by the dynamic flow pressure. This reduced amount of gas in the separator in turn causes a minimization of the pressure loss in the separator 1, whereby the gas quantities 24.1 are reduced.

This achieves the following advantages:

1. Reduction of wear in the classifier.

2. Increasing the amount of fine dust by classifier through better reflection conditions.

3. Increase of Nachmühlentemperatur by increasing the suction hot gas quantity.

4. Little effort in the realization.

5. Simple control or operation.

6. No additional drives required.

7. Increase in mill output.

8. Subsequent installation possible on existing systems.

9. Reduction of the classifier by reducing the amount of gas in the classifier.

At the mill suction side 15 (FIG. 11), the hot gas duct 7 is integrated into the transition part 3 via the opening 14. In Mahlkammerseitenwandbereich 18 of the mill 2, the opening 32 is provided immediately after the Schlagradleisten 31, offset from the opening 14, in which the hot gas channel 33 is integrated with flap 26. The hot gas channel 33 is combined with the hot gas channel 7 and forms the drying channel 34. The drying channel 34 is integrated into the separator 35, which is connected via the lock 36 with the bunker 37.

The trigger 38 of the bunker 37 is connected via the line 39 with the arranged on the combustion chamber 40 of the boiler burner 41. The exhaust air line 42 of the separator 35 is integrated either via the line 43 into the mill 2 or via the line 44 and vapor burner 45 in the combustion chamber 40.

The mode of action is the following:

From the mill 2 4 flue gas 27 is sucked in from the combustion chamber 40 via the flue gas return duct and passes with the coal 49 to be ground in the mill 2. About the opening 14 of the transition part 3 from the coal dust conveying gas mixture 25 warm gas 13 with Particulate dust 46 sucked. Due to the mill load is discharged by the distribution of the coal 49 on the Mühlensaugseite 15 a small but fine ground amount of dust. In addition, passes through the opening 32 hot gas 47 into the hot gas channel 33 and the hot gas channel 7. The amount of hot gas 47 is controlled by the flap 26 so that the corresponding Staubauflockerungsgrad is achieved, so that the fine dust 46 dries on the drying channel 34 sufficiently the cyclone 35 arrives. The exhaust gas 48 passes either via the line 43 back into the mill or via the line 44 and the vapor burner 45 in the combustion chamber.

Of course, all variants described are arbitrarily coupled together, so that in particular the separate deduction of low-dust conveying gas with much or little fine dust for Sichterumgehung, for the operation of ignition and support burners, Brüdenbrennern, to increase the performance of the fan mill and its wear reduction, but also for separate Feinstauberzeugung, bunkering and storage can be used. For the reduction in wear in the mill system, the disconnection and connection of low-dust conveying gas ducts in the edge area of the flow cross-section of the mill or transition piece can be used.

Thus, by switching off the conveying gas channel 6 and connecting the conveying gas channel 17 (FIG. 7), the conveying gas, but in particular the dust load at the outflow cross section, is directed in the direction of the flue gas suction side or spiral inner side and thus the mill wear increases in this area and the mill on the motor side is relieved of wear and / or spiral outside occur. Thus, a further reduction in wear and increase in service life of the mill can be achieved.

By adding marginal conveying gas channels occurring by leaks between the impact wheel and housing dust-free gas content can be used directly, so that expensive sealing measures can be omitted.

As a further advantageous new effect is relieved by the additional extraction of fine dust with conveying gas via additional delivery lines immediately after the spiral exit of the classifier and the semolina return of particulate matter.

This decisively improves the reflection, impact and grinding conditions in the classifier or in the mill.

Thus, the condition is given that the mill produces more fine grain without additional pressure loss.

The wear in the mill is decisively reduced.

By reducing the Grießrücklaufmengen or fine grain fractions of the mill is relatively humid semolina dust supplied for further drying. This increases the drying effect, and in addition a lower permissible temperature according to classifier for mill operation can be permitted.

Claims (22)

1. Arrangement for operating a pulverized coal fan mill, characterized in that openings are arranged with variable height for an opening height-dependent dust loading for the integration of delivery channels in the discharge part of the mill and / or arranged in a downstream part of the transition part and / or Abströmteil of the transition part. 2. Arrangement according to claim 1, characterized in that the openings are arranged on the outer side and / or motor side and / or rauchgasrücksaugseitig and / or spiral inside. 3. Arrangement according to claim 1 and 2, characterized in that the openings are arranged in edge regions. 4. Arrangement according to claim 1 to 3, characterized in that the openings are formed as longitudinal and / or transverse slots. 5. Arrangement according to claim 1 to 4, characterized in that the transition part is formed diffuser-like. 6. Arrangement according to claim 1 to 5, characterized in that the conveying channels are connected to main, support and / or vapor burners. 7. Arrangement according to claim 1 to 6, characterized in that the Ausströmquerschnitt by mill and / or the flow cross-section of the transition part and / or the outflow of the transition part divided into separate outflow ducts for coal dust conveying gas mixture and / or cold and / or hot gas is. 8. Arrangement according to claim 1 to 7, characterized in that, by visual cross-section, a semolina return channel with or without further Sichteinbauten, z. As cyclone, blinds, branch channels and / or channel constrictions, is arranged. 9. Arrangement according to claim 1 to 8, characterized in that the conveying gas channels are incorporated in separators and / or cyclones. 10. Arrangement according to claim 1 to 9, characterized in that the mill is associated with an additional metering device for aggregates, in particular limestone, dry dust or filter dust. 11. Arrangement according to claim 1 to 10, characterized in that the conveying channels are integrated on the suction side of the mill in the transition part. 12. Arrangement according to claim 1 to 11, characterized in that conveying channels are integrated via adjustable flaps in the transition part. 13. Arrangement according to claim 1 to 12, characterized in that viewing elements are arranged in conveying channels. 14. Arrangement according to claim 1 to 13, characterized in that conveying channels and the classifier are designed as multi-chamber view. 15. Arrangement according to claim 1 to 14, characterized in that the conveying channels are integrated at an angle of 10 to 15 ° in the transition part. 16. Arrangement according to claim 1 to 15, characterized in that arranged in the side region of the classifier, a vertically adjustable guide plate and is incorporated in the thus created Sichterteilraum the delivery channel via a flap. 17. Arrangement according to claim 1 to 16, characterized in that before the inlet gap of the guide plate, a rotating stator is arranged. 18. Arrangement according to claim 1 to 17, characterized in that in the conveying channel, a hot gas channel is integrated. 19. Arrangement according to claim 1 to 18, characterized in that the hot gas duct is integrated via an adjusting flap in the region of the corner armor in the mill. 20. Arrangement according to claim 1 to 19, characterized in that a separator is connected as a bypass to the classifier. 21. The arrangement according to claim 20, characterized in that the exhaust pipe of the separator is incorporated into the combustion chamber, in the Nachschaltheizflächenkanäle, the flue gas ducts to induced draft and / or in the suction side of the mill. 22. The arrangement according to claim 20, characterized in that the separator is connected to a bunker and / or support and / or pilot burner. For this 8 pages drawings