WO1994024486A1

WO1994024486A1 - Process and installation for burning organic materials and coal dust

Info

Publication number: WO1994024486A1
Application number: PCT/EP1994/001136
Authority: WO
Inventors: Franz Bauer; Horst Wetzel; Kurt STRÖER; Dieter Koritz; Detlef Witt; Herbert Schulze; Günter MÜLLELLERBUCHHOF; Siegfried Geisler; Klaus Klemprow; Otfried Blossfeld; Karin Grossmann; Matthias Mischke; Thilo Stahn
Original assignee: Veag Vereinigte Energiewerke Ag
Priority date: 1993-04-16
Filing date: 1994-04-13
Publication date: 1994-10-27
Also published as: AU6567894A; DK0694148T3; ATE154685T1; PL311160A1; FI954896A0; FI954896A; EP0694148A1; DE59403192D1; EP0694148B1

Abstract

The burning of organic materials is integrated into the operation of a steam boiler or fluidized bed furnace. This is done by feeding the organic material (34) as a fuel current or the flue gases generated from the drying, degassing or burning of the organic material as a flue-gas current into the coal pulverizing mill (15), flue-gas back suction system or combustion chamber (22) of the steam boiler (1) and withdrawing the combustion products as a combusted-material current via the flue-gas purification unit and as an uncombusted-material current via the wet-ash removal facility, with the uncombusted material fed back as fuel current into the coal pulverizing mill, flue-gas back suction system or combustion chamber or burn-out grate of the steam boiler.

Description

Process and plant for the combustion of biological substances and coal dust

The invention relates to a method and an arrangement for the combustion of biological materials, in particular wood chips, in a coal-fired steam boiler or a fluidized bed furnace.

For the incineration of bio-materials, such as wood waste, forest residues, plantation wood or renewable bio-materials (young trees, scrub, straw, reeds etc.) for the purpose of disposal, (landfill relief), recycling and disposal of bio-substances growing in regions (nature protection) and the reduction of CO2 From coal dust furnaces by substitution of raw lignite, it is known to operate additional furnaces or pre-furnaces in connection with coal dust-fired steam boilers (e.g. DD-PS 244 894, DD-PS 293 635, DD-PS 296 619, DE-OS 33 15 823, DE-OS 24 32 640, DE-OS 39 04 286, 30 31 154, DE-OS 34 44 480, DE-OS 35 29 615). The hot gases generated in the pre-firing are fed into the combustion chamber of the steam boiler. For the installation, regulation and operation of the pre-firing, however, considerable expenses have to be incurred in order to operate the pre-firing> 10 MW for a steam boiler> 50 MW stably and thus to achieve the desired effects.

All previously known measures represent only a partial solution to a single problem and do not result in a complex solution for the operation of a pre-firing in connection with a coal-fired steam boiler or a fluidized bed firing.

The invention has for its object to integrate the combustion of biological materials directly in a coal-fired steam boiler or a fluidized bed furnace.

SPARE BLADE RULE 26 This is achieved in that, according to the invention, the organic material is entered as a partial fuel flow and / or the flue gases generated from the drying, degassing and / or combustion of the organic material as a partial flue gas flow in the coal dust mill, flue gas recirculation and / or combustion chamber of the steam boiler, and the combustion products wherein the Unburned as a fuel split stream to the pulverizer, Rauchgasrücksaugung or combustion chamber of the steam boiler is recycled as a burnt part stream via the flue gas cleaning, and as a Outgoing ^* fired part stream is discharged via the Naßentaschungsanlage.

To achieve this, according to the invention, a biological agent feeder is integrated into the coal dust mill, flue gas suction and / or combustion chamber and / or into a drying, degassing and / or combustion device on a combustion chamber area of the steam boiler and the wet ash removal system of the steam boiler via an unburned feeder into the coal dust mill, Flue gas recirculation or combustion chamber of the steam boiler integrated.

The use of the method for the combustion of biological material in a fluidized bed furnace is such that the biological substance is entered into the fluidized bed furnace as a partial fuel stream and / or the flue gases generated from the drying, degassing and / or combustion of the organic substance are introduced into the fluidized bed furnace as well as the Combustion products are discharged as a burned partial stream via the flue gas cleaning system and the unburned product is returned to the fluidized bed furnace as a partial fuel stream.

SPARE BLADE (RULE 26) The invention is explained in more detail using an exemplary embodiment. The accompanying drawing shows

Fig. 1: The integration of the biological drying and degassing in the steam boiler system in principle

Fig. 2: The arrangement of the drying, degassing and combustion chambers provided with the burn-out grate on the combustion chamber end wall of the steam boiler in principle

Fig. 3: The arrangement in a side view

4: The integration of the pre-firing into the steam boiler system, the hot gases being conveyed from the pre-firing into the funnel area of the combustion chamber.

Fig. 5: The principle diagram of the circulation process on the coal-fired steam boiler

Fig. 6: The two-stage separation of the unburned

Fig. 7: The power plant with several steam boilers and a wet ash system

Fig. 8: The steam boiler system with direct return of the wet ash

Fig. 9: The structure of the flow and buffer arrangement in principle

10: The graphical representation of the course of temperature increase and water content reduction as a function of the storage period (greatly simplified)

SPARE BLADE (RULE 26) Fig. 11: The arrangement of the temperature measuring point in the wood chips pulp pile

Fig. 12: The principle of the arrangement of the pusher in the wood chip pile

Fig. 13: The arrangement of the stationary pusher with lateral removal in a schematic representation

The steam boiler 1 has the flue gas recirculation 2 and the grinding system 3 with a dust line 4 and burner 5 (FIG. 1). The raw coal shaft 6 and distributor 7 and the biological material shaft 8 with storage container 9 and distributor belt 10 are located on the flue gas return suction 2. The distributor 11 with the connecting duct 12 and / or the gas duct 13 is arranged below the flue gas return duct 23. The flue gas return chute 23 opens into the grinding system 3 and classifier 14 and / or into the additional grinding system 15 with classifier 16. Between the additional grinding system 15 and grinding system 3 there is channel 1 7, and / or the additional grinding system 15 has the dust shaft 18 with burner 19 or Blowing device 20 in the region of the end wall 21 of the combustion chamber 22.

The flue gas return duct 23 has the walling and the drying and degassing duct, the gas pipes with the openings, the central pipe with the opening slots or the partition with the gas openings.

The mode of operation consists in that hot flue gases 32 are sucked out of the combustion chamber 22 via the flue gas recirculation 2 from the grinding system 3 and / or additional grinding system 15 (FIG. 1). Raw lignite 33 is fed into the flue gas return duct 23 via the allocation device 7. Biological substances 34 are allocated at the same time as the coal flow. The organic substances 34 are allocated directly into the flue gas return 2 or into the drying and degassing shaft, which is surrounded by the hot gases 32 on all sides. The organic materials 34 are heated and degassed or partially burned. The resulting gases 35 pass through the connecting duct 12 and / or with the degassed and / or partially burned bio-substances 36 via the distributor 11 (FIG. 1) with the pre-dried raw lignite 48 into the grinding system 3. The bio-materials 36 prepared in this way are in the grinding system 3 milled as raw materials with the raw lignite 48 and fed to the burners 5 as a dust stream 37 via classifier 14 and dust channel 4.

However, it is also possible to supply the processed biological substances 36 to the auxiliary grinding plant 15 via the connecting duct 12 with the hot gas duct 49 via the gas duct 13. In the additional grinding system 15 and classifying system 16, the processed biological substances 36 are finely ground and introduced as a biological substance-dust mixture 38 via the channel 17 into the dust line 4 and / or via the dust shaft 18 into the burner 19. By supplying air 39 from the hot air duct 40, the biological substance-dust mixture 38 is burned in the flame 41 and / or blown into the dust flame 42 and burned via the blowing device 20 as a dust jet 47.

The biological substances 34 are passed around the gas pipes through which flue gases flow.

Hot gas partial flows 43 are conducted into the biological substances 34 via the openings 27. The stored organic substances 34 are thermally processed, made grindable and introduced into the grinding plant 3 and / or additional grinding plant 15. The back-sucked flue gases 32 flow through the central tube and the hot gas partial flows are fed to the biological substances 34 via the opening slots. For the thermal treatment of the biological substances 34, the hot gas partial flows are introduced into the biological substances 34 via the gas openings in the partition.

ERSATZBL TT (REGEL26) It is also possible for the resulting gases 35 to be fed directly to the grinding plant 3 via the gas duct 13 during the processing of the biological substances 34 and the processed biological substances 36 via the distributor 11 and the connecting duct 12 to the additional grinding plant 15 (FIG. 1).

With this separation, separate grinding or other use of the processed biological substances 36 can take place.

The steam boiler 1 with the combustion chamber 2, the ash funnel 3 and the pipe 4 has the coal dust mill 5 (FIG. 2). The coal dust mill 5 consists of the flue gas recirculation 6, the coal feed 7 of the coal dust line 8 and the coal dust burners 9. The fan 10 is connected to the burners 9 and the hot air box 13 via the hot air duct 11 and the combustion air line 12. The blowing device 15 for the biological substances 34 is arranged on the side and / or above the openings 14 for the flue gas recirculation 6 and is connected to the comminution device 16 (Hächsler, shredder), integrated hot air duct 17 and transport line 18. At a distance from the end wall 19 of the combustion chamber 2, the burnout chamber 20, consisting of the pipe system of the tubing 22, is arranged (FIG. 3).

The burnout chamber 20 has the sieve grate 23, the passage grille 21 and the air nozzles 26 with line 27 and control flaps 28.

The mode of action is as follows:

Hot flue gases 29 are sucked in by the coal dust mill 5 via the flue gas return suction 6 and, together with the coal 30, are fed to the coal dust burners 9 as a coal dust / flue gas mixture 31 after grinding via the coal dust line 8.

SPARE BLADE RULE 26 Due to the burner design, the flame 32 with the recirculation vortices 33 is maintained in the combustion chamber. If necessary, organic material 34 is supplied in different quality and shape via the line 18 and the blowing device 15 and hot air 35 from the hot air duct 11 to the burnout chamber 20. This organic material-hot air mixture 36 is blown onto the grate 23 with a relatively high impulse immediately above the openings 14 of the flue gas return suction 6.

It is also possible to provide distributor pipes 37 for distributing the mixture 36 over the width of the steam boiler 1. Correspondingly light bio-constituents burn in the burnout chamber 20 or are blown into the combustion chamber 2 and the recirculation vortex 33 with the burnout gas 24 via the passage grille 21. The high proportion of volatile constituents of the biological substances 34 requires the supply of air 39, which simultaneously acts as tertiary or secondary air for the coal dust combustion and the gas 38 is generated. In the upper part of the burnout chamber 20, the air 39 is regulated via the air nozzles 26 and is fed in through the regulating flap 28. The hard-to-burn portions 40 of the biological materials 34 fall onto the surface of the grate 23, burn out there further and, after extensive burn-out, fall in front of the openings 14 of the flue gas re-suction 6. The flue gases 29 which are sucked in and pass through the grille 21 as re-suction gas 25 into the lower part 41 the Ausbrandka mer 20 are sucked, carry the unburned portions of the biological substances 42 in the coal dust mill 5. In the coal dust mill 5 these difficult to burn parts 42 are ground, processed and blown into the combustion chamber 2 via the coal dust burner 3. A tipping or moving grating can be arranged as grating 23 without further notice. As a biological material 34 B. also use compressed flammable materials such as straw.

REPLACEMENT BLADE (RULE 26) The shaft with a lock is arranged in the side wall inside or outside the steam boiler 1. The shaft is designed as a treatment-degassing shaft and consists of the membrane wall, which is designed as a passage grille 21 in the upper part. The shaft is connected to the hot air duct 11 via the line 27. The burnout grate and / or shredder is arranged in the lower part of the shaft. The duct, distributor and the blowing mill are connected to the burnout grate. The burner is connected to the blowing mill via the line. The burner has a line with a control flap. The channels are optionally provided for the direct integration of the channel and / or shaft into the steam boiler 1.

The steam boiler 1 has the coal dust grinding system 2, the oil burner system 3, the scraper belts 4, the main air supply line 5, the ash funnel 6, the coal dust burner 16 and the combustion chamber 20 (FIG. 4). Directly next to the steam boiler 1, the pre-firing 7 with burner 30 and combustion chamber 12 is arranged.

The pre-firing 7 is connected to the bunker 9 (storage space) via the distributor 11 and the transport system 10. The pre-firing 7 has the oil burner 26, which is connected to the oil burner system 3 via the supply line 27. The burner 30 has the air box 31, which is connected to the main air supply line 5 via the air duct 32 and control device 14. The main air supply line 5 is integrated in the secondary heating surfaces 33 of the steam boiler 1 and connected to the fresh air fan 15. The combustion air line 34 leading to the coal dust burners 16 with hot air flaps 17 is integrated into the main air supply line 5. The pre-firing 7 is integrated into the ash funnel 6 of the combustion chamber 20 via the hot gas line 19 and connected to the wet ash disposal 25 via the ash line 23.

SPARE BLADE RULE 26 The pre-firing is optionally to be provided with the heating surfaces 28, which are integrated into the heating surface system of the steam boiler 1 or a heat consumer.

The pre-firing 7 is included in the safety emergency circuit 35 of the steam boiler 1.

The mode of action is as follows:

The supply of the biological materials 8 to the pre-firing 7 takes place from the bunker 9 via the transport device 10 and the distributor 11 to the burner 30 and into the combustion chamber 12. The required combustion air 13 is taken from the hot air duct 5 via the air duct 32 and according to the need by the control device 14 controlled.

To maintain a corresponding air pressure in front of the control device 14, the fresh fan 15 is fully extended and the air quantity control of the coal dust burner 16 is carried out via the hot air flaps 17.

With this switching state, a maximum hot air pressure in the hot air duct 5 is achieved. The hot gases 18 generated from the organic material combustion are passed via the hot gas line 19 into the ash funnel 6 of the steam boiler 1 at a negative pressure of approximately 20 kPa. The negative pressure in the area of the ash funnels 6 of the combustion chamber 20 supports the discharge of the hot gases 18 from the pre-firing 7.

However, it is also possible to operate the organic matter combustion with excess pressure.

The introduced hot gases 18 raise the temperature level in the combustion chamber 20 by maintaining hot gas vortices 21, mix with the combustion gases 22 from the dust firing and ensure good heat transfer to the boiler heating surfaces of the ash funnels 6.

SPARE BLADE (RULE 26) The excess air in the hot gases 18 with O2> 10% has the effect of burnout air with the largely complete combustion of CO in the safe temperature range t _f > 700 ° C. Any unburned fines that are carried along from the organic material combustion are completely burned out in the further gas path in the trains, in particular in the second train of the steam boiler 1. Because of this injection, the main firing of the steam boiler 1 with the coal dust burners 16 can be operated with a low excess of air with a correspondingly low NO _x formation in the area of the dust firing. The hot gases introduced with the 02 content of> 10% ensure the oxidation of CO to CO2 • This technology of blowing in far below the main firing of the steam boiler 1 acts like burnout air in a safe thermal temperature range, which reduces the CO content. The main firing with the coal dust-conveying gas mixture 29 is thus operated with a slight excess of air <1.3, so that the NO _x formation is lower.

The ash 24 from the organic material combustion is fed to the wet ash disposal 25 and / or the grinding plant 2 via the ash line 23. The oil burner 26 is arranged in order to ensure a constant burning of the bio-substances 8 in the pre-firing 7. Heat release of the hot gases 18 is made possible via the heating surfaces 28. With appropriate control of the entire system, consisting of steam boiler 1 and pre-firing 7, the organic material combustion can be operated intermittently or in terms of thermal output from minimum load to maximum load. Due to the introduction of the hot gases 18, the use of the disposal facilities 25 and the constant provision of hot air, a wide range of performance in the combustion of organic matter is ensured.

SPARE BLADE (RULE 26) In order to maintain the ignition of the bio-substances 8, the oil burner 26 with vapor pressure atomization in a power range of 2 to 5 MW can be implemented thermally and the hot gas re-suction from the combustion chamber. This eliminates the need for a separate oil supply.

The biofuel combustion in the pre-firing 7 has a maximum thermal output of approx. 60 MW, which corresponds to 20% of the firing output of the steam boiler 1 at full load (100 MW el.), And in part-load operation (70 MW el Max. 40 MW to operate thermally. With this range of services, the maintenance of the boiler control of the pulverized coal firing of the steam boiler 1 is ensured. It is not necessary or sensible to connect the boiler control to the pre-firing 7 for biofuel combustion, it complicates the entire system without any noteworthy advantages. In order to meet the switch-off conditions in the event of a malfunction, the pre-firing 7 is to be included in the safety emergency circuit 35. H. Switching off the oil burner 26 and interrupting the supply of the biological substances 8.

The removal of the combustion air 32 from the existing air supply system (t- ~ ~ 280 ° C) is unproblematic due to the existing reserves in the system. When the hot gases 18 from the pre-firing 7 are integrated into the dust boiler 1, the entire waste gas disposal, including dedusting, is ensured.

A separate emission measurement technology for the biofuel combustion in the pre-firing 7 is not necessary. The authorities are billed using the emission measurement technology of steam boiler 1.

The steam boiler 1 with the flue gas recirculation 2, the grinding system 3 and the coal dust burners 4 has the ash funnel 5 and the wet ash removal system 6 (FIG. 5). The wet ash discharge 7 ends above the wet ash belt 8.

26 The transport device 9 is integrated between the wet ash removal system 6 and the flue gas return suction 2. Immediately after the wet ash removal system 6, the separation system 10 is integrated. The organic material transport system 11 with the distributor 12 and organic material storage 13 is arranged in front of the grinding plant 3. The troughs 9.1; 9.2 of the wet ash removal system 6 of the steam boiler has the scraper chain 14 which runs with the upper run 15 in the water bath 16 and with the lower run 17 in the dry. The trough cheeks 18.1; 18.2 have the overflow 19. At the overflow 19 are the gutters 20.1; 20.2 connected, which open into the trough 21. The trough 21 has the sieve plate 22 and the water guide plate 23. The discharge device 35 with the cups 24 is inside the trough 21. The cups 24 are designed as sieves. Via the transport device 25 there is a connection between the discharge device 35 and the flue gas return 2 of the grinding system 3. The outlet channel 26 of the trough 21 has the suction line 27 with the pump 28. The pressure line 29 with the shut-off and / or control device 30 opens into the jet apparatus 31. To regulate the water level 32 there is the additional water line 33; 34.

The mode of action is as follows;

Raw lignite 36 is fed to the grinding plant 3 via the flue gas return 2 (FIG. 5). At the same time, the grinding plant 3 is mixed continuously and / or discontinuously with biological substances 37 via the transport system 11, allocator 12 and biological substance storage 13. The coal-bio-dust mixture 39 is blown into the combustion chamber 40 of the steam boiler via the dust line 38 and coal dust burner 4. Due to the poor grindability of the biological substances 37 in the grinding plant 3, some of the biological substances 37 precipitate as unburned 41 in the combustion chamber 40 via the ash funnel 5. These light portions of the unburned 41 float on the surface of the water bath 16 of the wet-ash plant 9 (FIG. 6). The unburned 41 is conducted into the overflow 19 with the aid of the jet apparatus 31 and / or guide devices. The water-unburned mixture 42 slides over the sieve plate 22 arranged in the trough 21, and the water 44 flows off. The unburned 41 is discharged by means of the discharge device 35 with its cup 24 with constant drainage. With the aid of the transport device 25, the unburned 41 reaches the flue gas return line 2 of the grinding plant 3 via the connection piece 43. The water 44 that runs off is fed again to the jet apparatus 31, controlled by means of the control device 30, by means of the pump 28 via the pressure line 29. The water loss is constantly caused by fresh water 45 via line 33; 34 filled up. Due to the thermal processing of the unburned 41, the grindability is improved and the proportion of the partially burned fractions that precipitate out is reduced. This reduction is made up by the constant supply of biological material 37 from the biological material storage 13. This constant circulation of unburned materials ultimately ensures that all of the organic matter is burned off in the coal dust furnace. The organic material supply is fixed at 5% to 30% of the thermal boiler output.

The power plant has the deep coal bunker 1 and the deep coal bunker 2 (FIG. 7). The deep coal bunker 1 with bunker pockets 27 has the track systems 3.1; 3.2 on. The transport system 4 exists between deep coal bunker 1 and deep coal bunker 2. Boiler 5.1; 5.2; 5.3 have the electrostatic precipitators 6.1; 6.2; 6.3, the wet ash conveyor system 7 and ^' the dry ash conveyor system 8. The transport system 10 exists between the wet ash belt system 7 and the wet ash bunker 9. The wet ash bunker 9 has the track system 11, which is connected to the track system 3.2. The dry ash transport system 8 is connected to the dry ash bunker 12. The track system 13 is located below the dry ash bunker 12. The transport system 17 from the wet ash removal system 29 is integrated in the boiler 5 between the combustion chamber 15 and the grinding system 16 (FIG. 8). The allocation device 18 exists between the coal bunker 2 and the flue gas recirculation 19 of the grinding plant 16. The funnel 30 of the combustion chamber 15 and the funnel 31 of the flue gas train 32 are integrated in the wet ash plant 29 via line 33. The boiler 5 has the burners 20 with the dust channel 21.

The mode of action is as follows:

The raw coal 22 is over the track system 3.1; 3.2 transported to the deep coal bunker 1. The pre-broken coal 23 is introduced into the coal bunker 2 via the transport system 4 (FIG. 7). For each boiler 5, the raw coal 23 is allocated to the grinding plant 16 via coal bunker 2 and allocation device 18 according to the power requirement (FIG. 8).

The coal 23 is ground in the grinding plant 16 and fed to the burners 20 as a coal dust / carrier gas mixture 14 via the dust channel 21. The coarse ash and the unburned 24 from the funnels 30; 31 are collected as wet ash 25 via the wet ash belt system 7, transport system 10 into the wet ash bunker 9. The wet ash 25 is continuously and / or discontinuously layered, tilted and / or stored in separate bunker pockets 27 by means of a track wagon 26 via the track system 11 onto the stored raw coal 22 in the deep coal bunker 1. The separately collected wet ash 25 is mixed with the pre-broken coal 23 from the bunker pockets 27. The wet ash lies on the coal 23 and absorbs the moisture. Coal 23 and wet ash 25 re-enter the grinding plant 16 in accordance with the transport routes.

RULES 26) Due to the wetting of the unburned material 24, a good thermal comminution takes place in the grinding plant 16, and the grindability of materials that are difficult to grind mechanically, such as wood chips, is also achieved. This circulation of the wet ash 25 is maintained until it is completely comminuted, incinerated and disposed of as fine ash, so that no wet ash to be disposed of arises from the power plant. The entire ash is removed as dry ash 28 from the electrostatic precipitator 6, disposed of via dry ash transport system, dry ash bunker 12 and track system 13. The coarse ash and the unburned 24 are allocated as wet ash 25 from the wet ash removal system 29 via the transport system 17 directly to the grinding system 16.

If alkaline and alkaline earth-containing organic matter is added to a furnace for a part of the coal, the coarse ash produced by the combustion is added to the flue gas as an additive to the combustion and / or fine ash to the flue gas path. This ensures that the SO _x -free biofuel combustion eliminates part of the SO _x emissions otherwise produced by coal combustion (dilution effect) and is used to bind the SO _x from the coal combustion due to the alkalis and alkaline earths released from the biofuel. This reduces the SO _x emissions according to the general relationship as follows:

RBK ^so x new ~ * ^so x old RBK + BM

where mean:

o _x new SO _x emission with organic substances S SOO _xv .a = _l ". ■ t_- SO _x emission without organic substances

RBK amount of coal

BM amount of organic matter. The invention is explained in more detail using an exemplary embodiment.

It is assumed that the raw lignite to be burned has a sulfur content of 0.5%, the organic material has a potassium content of 2% and z. For example, if you add 10% organic matter, the following results:

With a coal quantity of 100 t to be burned, this results in a released sulfur quantity of 500 kg, so that for the

Emission 2000 mg of sulfur per 1 Nm ^{3 of} flue gas are formed.

If the amount of coal is reduced to 90 t, a

450 kg of sulfur free. By adding 10 t of organic material for the combustion, no sulfur is released, but 200 kg of potassium.

Due to the molar mass ratio of S: 2K, the released potassium has a sulfur binding capacity with a degree of binding of n = 0.5

Mol S

S = • n • amount of potassium

Mol K

32

0.5 • 200 kg

2-41

39 kg

Therefore, only 411 kg of sulfur are released for the emission, so that the emission of mg

2000 on

Nm ³ 411 kg sulfur mg mg • 2000 = 1644

500 kg sulfur Nm ³ Nm ³

decrease.

That is, By replacing 10% coal with 10% organic substances, the sulfur emission is reduced by 17.8%. Depending on the amount of the organic material to be mixed, desulphurization can be achieved within the permissible limit values. To improve the mechanisms of action, the inactive parts of the coarse pockets, e.g. B. slag, and / or fine ash, e.g. B. sand, separated. The separation of the coarse ash by suspension in the wet ash removal system of the furnace and the circulation of the water also gives the advantage that the solubility limit of potassium salts is exceeded so that they do not dissolve and can enter the furnace process.

Due to the favorable technical, environmental and economic requirements, wood chips are burned as a mixed fuel with lignite in the furnace of the coal-fired power plant.

Wood chips from the whole-tree and thin-wood chopping carried out on site by chippers with the following delivery condition arrive at the power plant without intermediate storage:

Water content 43.

Wood chips composition Needles <5% bark <15%

Sapwood <80% heartwood ≤ 15%

Wood chips size 5 mm to 40 mm (including an unquantified

Fine grain fraction)

Density 250-350 kg / m ³

Before the wood chips are processed in the power plant for the storage and drying process, they have to be removed using a fine dust and magnetic separation. This separates fine grains and any metallic parts that may have entered, so that the subsequent process is not disrupted.

Then it is estimated how the storage time (drying time) and the water content will develop due to the delivery condition of the wood chips.

This estimate is based on the mathematical relationship:

x = at + x _f

with the areas

30 <x <x.

and

0 <t <40 Here mean:

t = drying time in days x = water content in% a = gradient of water content change in% per day x ₀ = water content as delivered

For the delivered wood chips batch, the following temporal behavior of the water content inside the pile results: with

x »- 0.3 t + 42

The wood chips are in the power plant on the prepared concrete surface 1 z. B. by means of a crane's grab from a minimal height as a loose heap 3 (FIG. 9).

This embankment in the form of the dam 2 up to a dumping height of approx. 6 m takes place at a dumping angle of approx. 45 °

Due to the quantity to be filled up (approx. 75 tons), the heap 3 results with the basic dimensions of 12 m length and 8 m width. A canopy is not necessary in normal weather conditions. Is to be expected with very heavy rainfall, a cover of the pile 3, z. B. with a special film.

The heap 3 thus constructed represents the continuous and buffer arrangement through which the dynamic storage and

Drying takes place.

The heap 3 remains after the construction of the continuous and

Buffer arrangement closed, so that the following

Temperature increases, including the decrease in water content, occur in heap 3 (Fig. 10): Day temperature water content reduction

Delivery day 7 ° C 43% after 7 days 35 ° C 40% after 16 days 55 ° C 38% after 30 days 60 ° C 35% after 34 days 74 ° C 32%

In the closed heap 3, due to the temperature increase inside, the water contained in the chips is evaporated and the water vapor is introduced into the cavities of the heap 3 through which the cooler ambient air flows released into the environment.

The reduction in the water content in the heap 3 is linked to the material flows which occur due to the temperature differences of the heap 3 to the ambient air and lead to a change in the wood moisture in the direction of the migration movement (drainage) of the warm moist air.

After a storage period of approx. 30 days, the water content has decreased by 25% reduced (Fig. 10). Extending the storage time does not result in a significant further reduction in the water content of the wood chips. Rather, the conditions for burning the wood chips have been reached, which ensure a technical, environmentally friendly and economical mode of operation. The pile 3 is removed in accordance with the conveying and dosing regime of the furnace.

For the continuous operation of the firing with wood chips, it is necessary to set up and operate a certain number of continuous and buffer arrangements. It will be a simple procedure to determine the

Drying condition of a wood chips pile for

Burning purposes described.

This is loosely heaped up on the base plate 1

Wood chips pile 2 stored (Fig. 11).

In the center of the pile 2, the temperature measuring point 3 is arranged, which is connected via line 4 to the temperature measuring and / or registering device 5. They are too

Spot checks possible.

Due to the loose bed, the natural drying of the pile 2 allows free convection of all areas, so that in the first drying phase a temperature of max. 80 ° C is reached. When this temperature was reached, the water content of the wood chips was reduced from> 40% to approx. 30%.

After this drying phase, a decision is made as to whether the wood chips are already suitable for combustion and are to be removed for firing, or whether the aggregate 2 should continue to be used to further reduce the moisture.

If the operation of the pile 2 is to take place in a second drying phase, the temperature measuring point 3 in the center of the pile is replaced by a moisture measuring point and connected to a moisture measuring and / or registering device.

Another temperature measurement is not real due to the mechanisms of action that occur in the second drying phase. The operation of the pile 2 then takes place on the basis of the determined development of the water content to an intended final value, for. B. of 25%.

The wood chips are then transported to the furnace and burned there.

On the base plate 1, the wood chips pile 2 is piled up (Fig. 12). Above the base plate 1 is the pusher 3 with drive 4 and along the heap 2 the conveyor

5 provided. The thrust device 3 has the thrust element

6, which is connected to the drive 4 via the drive rod 7. The thrust element 6 is wedge-shaped

Part 8 and the shield-shaped part 9 provided. The drive

4 is designed as an oscillating hydraulic drive. The portal device 11 is arranged in the longitudinal direction to form the pile 2 (FIG. 13). The portal device 11 has the movable support 12 which receives the thrust element 6. The thrust element 6 also has the wedge-shaped parts 13; 14 on.

It is also easily possible to arrange several rows of stationary thrust devices 3 above the base plate 1, which are provided with their own drives 4. The drive 4 is a mobile device, e.g. B. a tractor, can be trained to ensure the section feed movement (direction of travel).

It is easily possible to arrange the conveying device 5 centrally on the base plate 1 and to design the pushing devices 3 as partial pushing devices from the sides of the pile 2. As a result, the dry wood chips material is conveyed into the conveyor 5.

The mode of action is as follows:

With the drive 4, the thrust element 6 is set in oscillating movements and the dry wood chips material located in the interior of the pile 2 to the conveyor

5 promoted (Fig. 12).

This conveying process is realized with the shield-shaped part 9 of the thrust element 6. Through the wedge-shaped elements 8, the thrust element 6 returns to the starting position, so that again in the area of Thrust device 3 reaching dry wood chips is detected. The removal with the portal device 11 (FIG. 13) takes place in sections within the pile 2. By means of the wedge-shaped parts 13; 14 of the thrust element 3 ensures that propulsion of the thrust element 3 is possible within the pile. The dry wood chips material is fed via the conveyor 5 for firing z. B. promoted for a coal-fired steam boiler. The moist wood chip material located in the apex area and in the embankment areas of the heap 2 is only included in the conveying process to a small extent. This moist material remains on the base plate 1 at the end of the conveying process and forms the basis for a new pile to be built.

The following advantages are achieved by the invention:

I. Grinding of biological substances 2. Burning of biological substances with a large grain size range

3. Adherence to a necessary lay time and good preparation of the organic materials including determination of the drying status

4. Continuous and / or discontinuous delivery 5. Use of the incinerator of existing steam boilers

6. Use of the disposal system of an existing steam boiler system

7. Combustion of the biological substances in the high temperature field of the steam boiler. 8. The unburned is completely burned off by recycling

9. Reduction of the CO 2 content

10. Reduction of SO _x emissions

II. Application of the invention for fluidized bed combustion List of the reference numerals used for FIG. 1

1 steam boiler 47 dust jet

2 Flue gas recirculation 48 Raw lignite 3 Grinding system 49 Hot gas

4 dust pipe

5 burners

6 raw coal shaft

7 allocators 8 bio material chute

9 storage containers

10 allocation belt

11 allocators

12 connecting duct 13 gas duct

14 sifters

15 Additional grinding plant

16 sifters

17 channel 18 dust shaft

19 burners

20 blowing device

21 end wall

22 Combustion chamber 23 Smoke gas return duct

32 flue gas

33 raw lignite

34 organic fabric

35 gas 36 organic matter

37 dust flow

38 Bio-dust mixture

39 air

40 hot air duct 41 flame

42 flame of dust List of the reference numerals used for FIGS. 2 and 3

1 steam boiler 36 organic material / hot air mixture

2 combustion chamber 37 manifold 3 ash funnel 38 gas

4 tubing 39 air

5 coal dust mill 40 share

6 smoke evacuation system 41 lower part

7 Coal supply 42 Bio material 8 Coal dust pipe

9 coal dust burners

10 fans

11 hot air duct

12 Combustion air line 13 Hot air box

14 openings

15 blowing device

16 shredding device

17 Hot air duct 18 Transport line

19 end wall

20 burnout chamber

21 passage grille

22 Tubing 23 Sieve screen

24 burnout gas

25 return gas

26 air nozzle

27 Line 28 control flaps

29 flue gas

30 coal

31 Coal dust and flue gas mixture

32 flame 33 recirculation vortex ^" 34 organic material 35 hot air List of the reference numerals used for FIG. 4

1 steam boiler

2 coal dust grinding system 3 oil burner system

4 scraper tape

5 Main air supply line

6 ash funnels

7 pre-firing 8 organic material

9 bunkers

10 transport system

11 allocators

12 combustion chamber 13 combustion air

14 control device

15 fresh air fans

16 coal dust burners

17 Hot air flap 18 hot gas

19 hot gas line

20 combustion chamber

21 hot gas vortex

22 Fuel gas 23 Ash pipe

24 ashes

25 wet ash disposal

26 oil burners

27 supply line 28 heating surface

29 Coal dust and feed gas mixture

30 burners

31 air box

32 Air duct 33 Post-heating surface

34 Combustion air line

35 Safety and emergency switching List of the reference numerals used for FIGS. 5 and 6

1 steam boiler 31 jet apparatus

2 smoke evacuation 32 water level

3 Grinder 33 Additional water pipe

4 coal dust burners 34 Additional water pipe

5 ash funnels 35 discharge device

6 wet ash removal system 36 raw lignite

7 wet ash discharge 37 organic matter

8 wet ash band 38 dust pipe

9 Transport device 39 Coal-organic dust mixture

9.1 Trough 40 combustion chamber

9.2 Trough 41 unburned

10 separation plant 42 water-U burned mixture

11 Biofuel transport system 43 sockets

12 allocators 44 water

13 Biological storage 45 fresh water

14 scraper chain

15 upper run

16 water bath

17 lower run

18.1 Trough cheek

18.2 Trough cheek

19 overflow

20.1 Drainage channel

20.2 Drainage channel

21 trough

22 sieve plate

23 water guide floor

24 cups

25 transport device

26 drain channel

27 suction line

28 pump

29 pressure line

30 control device List of the reference numerals used for FIGS. 7 and 8

1 deep coal bunker 28 dry ash

2 coal bunkers 29 wet ash removal system 3.1 track system 30 funnels

3.2 Track system 31 funnels

4 Transport system 32 flue gas flue

5 boiler 33 pipe 5.1 boiler 5.2 boiler

5.3 boiler

6.1 electrostatic precipitators

6.2 electrostatic precipitators

6.3 Electrofilter 7 wet ash conveyor system

8 Dry ash transport system

9 wet ash bunkers

10 transport system

11 Track system 12 Dry ash bunker

13 track system

14 coal dust / carrier gas mixture

15 combustion chamber

16 Grinding plant 17 Transport plant

18 Allotment device

19 smoke evacuation

20 burners

21 dust channel 22 raw coal

23 coal

24 unburned

25 wet ash

26 rail wagon 27 bunker bag List of the reference numerals used for FIG. 11

1 base plate

2 heap 3 temperature measuring point

4 line

5 Temperature measuring and / or registration device

List of the reference numerals used for FIGS. 12 to 13

1 base plate

2 wood chips piles 3 pusher

4 drive

5 conveyor

6 thrust element

7 drive rod 8 wedge-shaped part

9 shield-shaped part

10 row

11 portal setup

12 movable support 13 wedge-shaped part

14 wedge-shaped part

Claims

Process for the combustion of bio-material, in particular wood chips, in a coal-fired steam boiler, characterized in that the bio-material as a partial fuel flow and / or the flue gases generated from the drying, degassing and / or combustion of the organic material as a partial flue gas in the Coal dust mill, flue gas suction and / or combustion chamber of the steam boiler entered and the combustion products are discharged as a burned partial flow via the flue gas cleaning and as an unburned partial flow via the wet ash removal system, the unburned as a fuel partial flow into the coal dust mill, flue gas suction or combustion chamber and / or Burnout rust of the steam boiler is returned.

2. The method according to claim 1, characterized in that the biological substances in the flue gas return system

Steam boiler abandoned, self-dried and degassed and separated or fed in together with the coal of the coal dust mill of the steam boiler and / or an additional mill.

3. The method according to claim 2, characterized in that the organic materials ground in the additional mill are conveyed into the coal dust channel of the cooling dust mill.

4. The method according to claim 2, characterized in that the ground organic substances in the additional mill promoted in a separate coal dust channel and the

Burner system or a separate burner system can be supplied.

5. The method according to claim 2 to 4, characterized in that the volatile degassing components are introduced directly into the flue gas back-suction system.

6. The method according to claim 2 to 4, characterized in that the volatile degassing components are promoted with the degassed biological substances in the coal dust mill.

7. The method according to claim 2 to 4, characterized in that the part of the volatile degassing components are fed directly into the flue gas re-suction system and the other part with the degassed biological substances in the coal dust mill.

8. The method according to claim 2 to 4, characterized in that hot gas from the flue gas back-suction system is introduced into the biological materials.

9. The method according to claim 2, characterized in that hot gas is introduced from the combustion chamber into the biological materials.

10. The method according to claim 2 to 9, characterized in that the biological substances are conveyed in a separate drying and degassing channel acted upon by the hot or return gas of the steam boiler.

11. The method according to claim 10, characterized in that the volatile degassing components are conveyed into the combustion chamber and / or the coal dust burners and / or the flue gas flues of the steam boiler.

12. The method according to claim 1, characterized in that the biological substances in and / or on a combustion chamber area of the steam boiler are dried and degassed and burned and that the unburned of the biological substances in the Rauchgasrück¬ suction and / or the coal dust mill is promoted.

13. The method according to claim 12, characterized in that the biological materials are blown with hot air from the steam boiler on a grate and the fuel gases generated are supplied with secondary air from the hot air system of the coal dust burner.

14. The method according to claim 13, characterized in that the unburned incurred below the grate is promoted in the area of the flue gas recirculation.

15. The method according to claim 12, characterized in that the biological materials are fed to a drying and degassing chamber, the fuel gases of the combustion chamber and hot air are introduced and the unburned pulverized coal mill and / or an additional mill is supplied.

16. The method according to claim 15, characterized in that the unburned is promoted via the additional mill in the coal dust duct of the coal dust mill and / or via the biological material duct in a burner.

17. The method according to claim 15 and 16, characterized in that the fuel gas is conveyed from the drying and degassing chamber into the flue gas recirculation and / or in the coal dust duct.

18. The method according to claim 12, characterized in that the biological materials are conveyed on an inclined path through the combustion chamber and subjected to hot air.

19. The method according to claim 12, characterized in that the biological materials are conveyed into a burnout shaft operated with a grate or fluidized bed.

20. The method according to claim 1 with a pre-firing, characterized in that the pre-firing directly with the hot air, pilot burner, grinding system, main burner, combustion chamber, heating surface, flue gas and ash removal system and with the safety and emergency switching of the steam boiler is driven. ^'

21. The method according to claim 20, characterized in that the bio-materials are allocated to the pre-firing, the hot air and the pilot oil are introduced in a controlled manner depending on the degree of drying of the bio-materials, the hot gases from the pre-firing are conveyed into the funnel area of the combustion chamber of the steam boiler and the ash from the pre-firing is introduced into the wet ash removal and / or grinding plant of the steam boiler.

22. The method according to claim 20, characterized in that the unburned is conveyed from the pre-firing into the flue gas recirculation.

23. The method according to claim 1, 14, 15, 16, 20, 21 and 22 for the complete burning of unburned, characterized in that the incinerated in the wet ash plant of the steam boiler from the biofuel and coal dust combustion in a known manner by The floating effect is hydraulically separated from the non-combustible, the unburned is held up by the water by filtering and continuously added to the mill, flue gas return or burner system of the steam boiler as secondary fuel.

24. The method according to claim 23, characterized in that the filtering is carried out in two stages by the stationary in a first stage and in a second stage in the transport process, the unburned is separated from the water.

25. The method according to claim 23 and 24, wherein the coarse ash-unburned mixture of the raw coal is charged, characterized in that the coarse ash-unburned mixture is driven in the wet-ash system-fuel feed-combustion chamber and gradually burned as well as gradually after one or more cycles Fine ash through which flue gas flues are disposed of.

26. The method according to claim 1 to 25 for reducing the Sθ2 ~ emission during the combustion of SO _x- containing coal, characterized in that the furnace for a part of the coal alkali and alkaline earth-containing biological material is given, the coarse ash produced by the combustion as an additive the combustion and / or fine ash are added to the flue gas path as an additive to the flue gas.

27. The method according to claim 1 to 26 for drying organic matter, in particular from wood chips

Coniferous wood, characterized in that the organic material, in particular wood chips, are dynamically stored and dried in the as-delivered state in a heap of loose, natural drainage, built-up, continuous and buffer arrangement with a solid surface, and the continuous and buffer arrangement in Depending on the composition of the wood chips, the water content, the outside temperatures and the amount of precipitation is operated for a limited time.

28. The method according to claim 27, characterized in that the water content for the center of the pile according to the mathematical relationship x = at + xo

for the areas

30 <x <x _f

and

0 <t <40

is determined; mean:

t = drying time in days x = water content in% a = gradient of water content change in% per day x ₀ = water content in delivery condition in%

29. The method according to claim 27 for determining the drying state, characterized in that the temperature in the center of the pile is measured in a first drying phase and, after reaching a maximum temperature of approx. 80 ° C, a water content of approx. 30% is concluded and in that with further natural drying in a second drying phase, the moisture in the center of the pile is measured in a manner known per se.

30. The method according to claim 27 for the removal of a biomass cluster, characterized in that the

Biological material from the lower area of the pile, which is stored directly above the subsurface, is oscillated transversely to the pile structure and is conveyed in sections into a known conveyor system arranged longitudinally to the pile structure.

31. Arrangement for the combustion of biological material, in particular wood chips, in a coal-fired steam boiler, characterized in that a biological substance distributor is integrated in the coal dust mill, flue gas re-suction and / or combustion chamber and / or in a drying, degassing and / or combustion device on a combustion chamber area of the steam boiler is and the wet ash removal system of the steam boiler is integrated into the coal dust mill, flue gas recirculation system or combustion chamber and / or burnout grate of the steam boiler via an unburned distributor.

32. Arrangement according to claim 31, characterized in that the organic material distributor with the flue gas return system of

Steam boiler is directly or indirectly connected and integrated into the coal dust mill of the steam boiler and / or an additional mill and that the discharge channel of the additional mill is integrated into the flue gas return system, into the coal dust burner system, into a separate burner system or into the combustion chamber.

33. Arrangement according to claim 32, characterized in that the organic material distributor is integrated into a drying and degassing duct arranged in the flue gas return suction system.

34. Arrangement according to claim 31, characterized in that a drying, degassing and combustion device is arranged in and / or on a combustion chamber area, in which an allocator is integrated and which is connected to the flue gas recirculation and / or the coal dust mill.

35. Arrangement according to claim 31 with a pre-firing, characterized in that the pre-firing directly into the steam boiler hot air, ignition burner, grinding, main burner, combustion chamber, heating surfaces, flue gas and de-ashing system is integrated and coupled with the safety and emergency switching of the steam boiler.

36. Arrangement according to claim 35, characterized in that in the combustion chamber of the pre-firing a biofuel distributor with biofuel burner is integrated, the biofuel burner is connected to the hot air system of the steam boiler and the combustion chamber of the pre-firing is integrated into the combustion chamber as well as the pre-firing de-ashing system in the wet de-ashing system of the steam boiler.

37. Arrangement according to claim 31 to 36 for the complete burning of unburned material, characterized in that the wet ash removal system of the steam boiler is connected to an unburned non-combustible water separating device and this is integrated into the mill, flue gas return suction or burner system.

38. Arrangement according to claim 37, characterized in that the wet ash removal system is connected via a line system with the fuel feed of the steam boiler.

39. Arrangement according to claim 31 to 36 for conveying a pile of organic matter, wherein the organic matter is stored as a loose pile on a solid and level surface, characterized in that directly above the surface provided with an oscillating drive with a shield and wedge-shaped Partly provided pushing elements having a pushing device is arranged.

40. Use of the method for the combustion of biological material, in particular wood chips for fluidized bed combustion, characterized in that the organic material as a partial fuel flow and / or the flue gases generated from the drying, degassing and / or combustion of the organic material as a partial flue gas flow into the Fluidized bed combustion entered and the combustion products discharged as a burned partial stream via the flue gas cleaning and the unburned is returned to the fluidized bed combustion as a partial fuel stream.

13 pages of drawings