EP0843141A1 - Coal feeding device for a brown coal drying plant - Google Patents

Abstract

The plant for drying unrefined brown coal in a fluidised bed, comprises gas-tight supply chutes (32-35) and following distributors (36-39) situated in a heated chamber (40) above drying units (1-8) into which the material is delivered at a controllable rate.

Description

The invention relates to a coal feed device for a plant for steam fluidized bed drying of broken Raw lignite, which has at least two drying units includes.

As a consequent further development of lignite-based electricity generation is the use of power plants of great performance and upstream drying of the raw lignite.

• der hohe Wassergehalt von 50 % - 60 % der Rohbraunkohle,
• der erforderliche niedrige Wassergehalt für Folgeprodukte, wie Briketts, Koks oder Kohlenstaub von 12 % - 18 % für eine stoffliche Nutzung,
• der erforderliche niedrige Wassergehalt für eine rationelle energetische Nutzung in Verbrennungsanlagen in einem Dampfkraftwerksprozeß, einem Gas-Dampf-Kombiprozeß mit integrierter vorgeschalteter Kohlevergasung- oder Druckwirbelschichtverbrennungsanlage.

Characteristics for brown coal drying plants are:

• the high water content of 50% - 60% of raw lignite,
• the required low water content for secondary products such as briquettes, coke or coal dust of 12% - 18% for material use,
• the required low water content for a rational energetic use in incineration plants in a steam power plant process, a gas-steam combination process with an integrated upstream coal gasification or pressure fluidized bed combustion plant.

The upstream is separate for this power plant technology Drying is essential. The possible increase in efficiency through an energetically favorable The greater the drying process, the higher the drying process water content to be reduced.

In addition to drying in tube dryers, there is also Steam fluidized bed drying of the broken raw lignite known. Such steam fluidized bed dryers belong to inter alia by DE-OS 37 24 960 or DD 224 649 A1 on the prior art. The broken one Raw lignite using steam as Fluidizing fluidized. By contacting the raw lignite with the heat exchanger wall and by convective heat transfer the resulting coal water vapor and the The so-called drag air is used to heat the raw lignite and expelled water.

In the future, the performance of lignite power plants rising more and more. The previously used lignite drying processes then the demands made can only withstand to a limited extent as drying systems integrated in power plants with dryer throughputs of 120 t / h raw coal are targeted. To guarantee the highest possible availability and operational reliability the power plant blocks will be built as part of an older but not pre-published European patent application proposed the required amount of coal on a dryer line consisting of several drying units split up.

Each drying unit includes a modular design a trigger unit in a vertical stacking arrangement for dried brown coal, one nozzle base unit, one Heat exchanger unit, a steam fluidized bed dryer unit and a feed unit for raw lignite.

This concept ensures that the availability of a Power plant with more than 7500 operating hours per year is not affected by the coal predrying.

The raw lignite becomes a drying unit via a cellular wheel sluice and into the steam fluidized bed dryer unit integrated screw conveyor given up. This facility has proven itself. Basically but is a further development for improvement of the coal entry process and to reduce the Desirable susceptibility to failure.

The invention is therefore based on the object of a coal feed device for a system for steam fluidized bed drying broken raw lignite to improve.

According to the invention, this object is achieved in those listed in the characterizing part of claim 1 Characteristics.

Thereafter, the coal feed device comprises at least a gas-tight allocation device, which is followed by a conveyor is. Allocation device and conveyor are in arranged a pre-treatment room. It is located above the drying units and is therefore outside the hydrocarbon atmosphere. The raw lignite is adjustable from the conveyor in the longitudinal direction of the conveyor transferred to the drying units.

A cellular wheel sluice preferably comes as the allocation device for use. Mechanical conveyors are continuous conveyors suitable with or without traction means. For the The use of a chain scraper conveyor is practical on. Basically, however, are link belt or trough chain conveyors suitable as well as screw conveyors.

When connected from several drying units Lignite drying plants are useful multiple allocation devices and multiple conveyors intended. The individual drying units are then via the conveyor with wet lignite in line with the quantity required acted upon.

In addition to the distribution, the pre-treatment room is also used for Preheating wet brown coal. The pre-treatment room can be used for this in various ways, directly or indirectly are heated, for example by means of steam or Hot air. Heating the conveyor is also conceivable by means of suitable heating means, such as heating coils.

This way the cold wet brown coal that comes out a storage bunker on the allocation devices on the Conveyor arrives, are preheated in the pre-treatment room. Temperatures of over 100 ° C can be reached.

By preheating the wet brown coal Flow behavior improved and the tendency to stick greatly reduced. Consequently, malfunctions are caused by Contamination and blockages prevented.

Another major advantage is that it is already preheated Wet lignite in the fluidized bed of the drying units is abandoned. This creates stability supports the fluidized bed and improves the Fluid bed operating conditions reached. This ensures a high degree of dryness with high throughput.

Both the allocation devices and the conveyors are easily accessible from the outside and can therefore be easily maintained will. Because the pre-treatment room is outside the hydro-steam atmosphere, it can also to maintenance or during the operation of the drying system For repairs.

According to the features of claim 2, a conveyor Cross-adjustable discharge openings distributed over its length on. In this way, the application can of the individual drying units with wet brown coal regulated according to quantity requirements and dependent be controlled by the operating conditions.

When using a chain scraper conveyor, for example the discharge openings are in its bottom. A Chain scraper conveyor extends over several each Drying units. The discharge openings are then arranged above the drying units. Means The opening cross-section of the discharge openings can be a slide changed and the discharge regulated. The individual drying units will then be the required Amount of wet brown coal allocated.

The wet lignite passes from the conveyor via discharge chutes in the drying units, as this claim 3 provides.

A further developing the general idea of the invention Embodiment is characterized in claim 4.

After that, all drying units of the lignite drying plant assigned to a common steam collection chamber. Furthermore, the heat exchanger units are the Drying units through a partition in at least divided into two vertically aligned fluidized bed cells. The feed chutes pass through the steam collection chamber, around the fluidized bed cells with wet lignite to act upon.

By dividing the heat exchanger unit into two Fluid bed cells can cover the area of the fluid bed of a drying unit adjusted in its dimensions that stable fluid bed operating conditions available. This will result in intense heat transfer and achieved a high drying success. Also there is an essential one with regard to litigation Improvement of the overall system because of the fluidized bed in the fluidized bed cells much less sensitive reacts to changing operating parameters, for example different when giving coal Moisture content.

The fluidized bed cells preferably have dimensions of ² × ² m, so that fluidized bed areas of 4 m ² result.

It is expedient to have one in each heat exchanger unit Bundle of U or V-shaped heat exchanger tubes integrated. The heat exchanger tubes penetrate here the partition. The partition is perforated for this purpose and the heat exchanger tubes are through these openings guided. The partition therefore takes over additional support and Stabilization functions for the heat exchanger tube bundle.

In the fluidized bed cells of a drying unit the one fed continuously from above via the feed unit Raw lignite from the fluidizing medium from bottom to top flows through. The raw lignite becomes the fluidizing medium expelled hydro steam used. The amount vortex medium and the flow velocity are so matched that the raw brown coal bed in the fluidized bed transforms. The vortex speed is there above the vertebral point and remains approximately constant regardless of the coal mass flow. This is achieved through a steam cycle to which at least to overcome the flow loss still belongs to a blower, which is always part of the hydro-steam in the cycle promotes. The one flowing into the drying units Steam becomes pressure-dependent with a small temperature difference overheated.

The weight of the lignite grains is in the fluidized bed by the opposite flow force of the vortex medium almost canceled. The fluidized Lignite coal then behaves like a liquid and flows through the heat exchanger unit. Here an intensive heat transfer takes place high turbulence instead and that contained in the raw lignite Water is evaporated. This way, a reliable one Drying the raw lignite to almost any residual water content can be achieved.

Figur 1

eine Trocknungsanlage in der Seitenansicht;

Figur 2

einen vertikalen Querschnitt durch die Anlage;

Figur 3

einen horizontalen Querschnitt durch die Darstellung der Figur 1 entlang der Linie A-A;

Figur 4

eine Draufsicht auf einen Rostdüsenboden und

Figur 5

die Düse eines Düsenrohrs im Vertikalschnitt.

The invention is described in more detail below with reference to the exemplary embodiments illustrated in the drawings. Show it

Figure 1

a drying plant in the side view;

Figure 2

a vertical cross section through the plant;

Figure 3

a horizontal cross section through the representation of Figure 1 along the line AA;

Figure 4

a plan view of a grate nozzle bottom and

Figure 5

the nozzle of a nozzle tube in vertical section.

Figures 1 to 3 show one out of a total of eight Drying units 1-8 existing dryer line 9. How the individual can be seen from FIG Drying units 1-8 in pairs in groups 10, 11, 12, 13 interconnected. Figure 2 illustrates the Construction of a drying unit 1-8.

A trigger unit is arranged vertically one above the other 14 for dried brown coal TBK, a nozzle base unit 15, a heat exchanger unit 16, a steam fluidized bed dryer unit 17 and a task unit 18 for the wet raw lignite FBK.

Each heat exchanger unit 16 is vertical by one aligned partition 19 in two vertically aligned Fluidized bed cells 20, 21 divided. With that, dryer street 9 shown here a total of sixteen Fluid bed cells 20, 21.

Above the steam fluidized bed dryer units 17 a common vapor collection chamber 22 is arranged. Output side of the steam fluidized bed dryer units 17 are internals 23 in the form of grate floor units 24 intended. The grate floor units 24 consist of two Layers of one another and offset from one another Angle profiles 25. The internals 23 cause one Pressure loss in the drying units 1-8, so that a Uniformization of the volume flow in all drying units 1-8 is done. As a result, all drying units 1-8 always almost the same amount of hydro-steam KWD deducted, regardless of how far the individual drying units 1-8 from the location the outlet 26 of the vapor collection chamber 22 are removed.

Furthermore, the internals 23 take on a cleaning function, there entrained dust from the hydro-steam KWD is deposited on them.

About the steam collection chamber 22 from the Drying units 1-8 escaping hydro-steam KWD deducted and not through the outlet 26 here shown aftertreatment with dedusting, Reheating and circulation fan supplied.

Purified hydro-steam KWD is used as a fluidizing medium WM returned to the system via the nozzle base unit 15. Furthermore, the cleaned and heated hydro steam KWD as heating steam HD for the heat exchanger unit 16 can be used.

During operation, each drying unit becomes 1-8 damp Lignite FBK in a grain size range from 0 to 10 mm fed by the task unit 18.

For this purpose, the feed unit 18 is carried out from the bunker 27 Wet brown coal fed FBK. Arrived from bunker 27 the wet lignite FBK via four bunker funnels 28-31 in four rotary locks 32-35. These give the wet lignite FBK on four chain scraper conveyors 36-39. Two chain scraper conveyors 36, 38 and 37, 39, respectively lie side by side, with the chain scraper conveyor 36, 38 on the drying units 1-4 and the chain scraper conveyor 37, 39 on the drying units 5-8 extend.

The rotary valve 32-35 and the chain scraper conveyor 36-39 are in a closed pre-treatment room 40, the drying units above 1-8 the steam collection chamber 22 is arranged. The pre-treatment room 40 can be heated so that preheating the FBK wet brown coal can be made. The Preheating improves the flow behavior of the wet lignite FBK. Since the pre-treatment room 40 is outside the hydro-steam atmosphere, it can easily also during the operation of the drying system Maintenance or repair purposes.

From the chain conveyors 36-39 the wet brown coal FBK via discharge chutes 41, 42 into the individual Fluidized bed cells 20, 21 passed. There are in the bottoms 43-46 of the chain conveyor 36-39 over their Length distributes discharge openings 47, 48 above the discharge chutes 41, 42. The opening cross section of the discharge openings 47, 48 is by means of sliders 49, 50 adjustable. By adjusting the slide 49, 50 is the individual fluidized bed cells 20, 21 in operation supplied wet lignite FBK according to quantity requirements regulated. The control is automated by a central operations control center. The slide actuators are designated 51, 52.

The bunker 27 is located centrally in the middle above dryer street 9. Via bunker funnels 28-31 and The cellular wheel locks 32-35 get the wet lignite on the four chain scraper conveyors 36-39. From here the wet lignite in the image plane of FIGS. 1 and 3 transported to the right or left.

It is clear from FIG. 3 that initially a part who transported on the chain scraper conveyors 37, 39 Wet brown coal through the outlet openings 47 and 48 falls into the drying unit underneath 5 or its fluidized bed cells 20, 21 arrives.

The wet lignite then falls during further transport through the discharge openings 47 ', 47' ', 47' '' or 48 ', 48' ', 48' ''. This way it becomes a continuous one Distribution of wet lignite FBK to the individual Drying units 1-8 made. Whichever Drying unit 1-8 straight with wet lignite FBK individual discharge openings can also be loaded 47-47 '' 'or 48-48' '' can be closed.

For loading the drying units in accordance with the quantity required 1-8 can also be provided that the conveying speed the chain scraper conveyor 36-39 continuously is adjustable.

The FBK passes through the discharge chutes 41, 42 Steam collection chamber 22 and enters the steam fluidized bed dryer unit 17th

The wet lignite FBK then falls down against it upward flowing vortex medium WM. As a vortex medium WM comes the expelled from the FBK wet brown coal and cleaned hydro-steam KWD used.

The steam fluidized bed dryer unit 17 comprises one Chamber 53 which widens in a trapezoidal shape. The cross-sectional expansion will reduce the speed of the hydro-steam flowing upwards KWD reached. This will remove fine grain reduced.

Below the steam fluidized bed dryer unit 17 is the heat exchanger unit 16 is arranged. Above the Heat exchanger unit 16 passes the brown coal bed into the fluidized bed through the heat exchanger unit 16 continues. The fluidized brown coal then flows through the fluidized bed cells 20, 21.

In the heat exchanger unit 16 are two in one another nested bundles 54, 55 of U-shaped configuration Heat exchanger tubes 56, 57 integrated. Every heat exchanger tube 56, 57 has longitudinal tube sections inclined to the horizontal 58, 59 on the vertical pipe sections 60, 61 merge.

The heat exchanger tubes 56, 57 summarized in a tube sheet 62. The steam distribution chamber 63, 64 and the condensate collection chambers 65, 66 each bundle 54, 55 are arranged on the same side. Via a steam manifold 67 and the manifold 68 is fed to the steam distribution chambers 63, 64 heating steam HD. This flows through the heat exchanger tubes 56, 57, their inclination for continuous drainage of the resulting condensate K. The condensate K occurs into the condensate collection chambers 65, 66 and is about deductions 69, 70 removed.

Due to the U-shaped hairpin configuration of the heat exchanger tubes 56, 57 are strains due to Changes in temperature are harmless.

Each heat exchanger unit 16 is separated by a partition 19 divided into two fluidized bed cells 20, 21. The Partition 19 is penetrated by bundles 54, 55. For this purpose, in the partition 19 to the cross section of the Heat exchanger tubes 56, 57 provided adapted openings. The heat exchanger tubes 56, 57 are through the openings passed through. They are carried by the partition 19 and stabilized.

A unit from bundles 54, 55, partition 19, tube sheet 62 and steam collecting chambers 63, 64 and condensate collecting chambers 65, 66 can be pre-assembled in the heat exchanger unit 16 can be installed transversely.

In the nozzle base unit 15 there are two grate nozzle bases 71, 72 incorporated. As shown in Figure 4, everyone exists Grate nozzle base 71, 72 from a row parallel and side by side horizontal nozzle pipes 73. The grate nozzle bottoms 71, 72 are inserted into the nozzle base unit from one side 15 inserted. The loading of the grate nozzle bottoms 71, 72 with vortex medium WM is carried out from the vortex medium ring line 74 from via the feed lines 75, 76 and the Distribution lines 77, 78. The vortex medium WM then occurs out through nozzles 79 and flows up through the fluidized bed cells 20, 21.

FIG. 5 shows the structure of a nozzle 79.

The nozzle 79 includes a nozzle tube 73 fixed to the vertically upward nozzle 80, which by a Cap 81 is closed. At the top 82 are radial Nozzle openings 83, 84 arranged.

The vortex medium WM passes through an opening 85 in the nozzle tube 73 in the nozzle 80 and flows through the nozzle openings 83, 84 radially. This is where the vortex medium gets WM in a between socket 80 and cap wall 86 located in the annular space 87. In the annular space 87, the vortex medium WM first flow downwards before crossing the Annular gap 88 can emerge. Through this training the Nozzle 79 is avoided that fine-grained brown coal in the Nozzle openings 83, 84 can flow. This will cause constipation the nozzle tubes 73 prevented.

To achieve the fluidized bed in every drying unit 1-8 is cleaned hydro-steam KWD as a fluidizing medium WM on the nozzle base unit 15 and the grate nozzle bases 71, 72 initiated. This depends on the pressure overheated with a small temperature difference. Of the Hydro-steam KWD flows through the wet lignite FBK on the way through the heat exchanger unit 16 or the fluidized bed cells 20, 21 and the steam fluidized bed dryer unit 17 from bottom to top. Here the lignite to be dried is Hydro-steam KWD in a suspended state transferred. The amount of hydro-steam introduced KWD and the inflow speed are designed so that in Area above the heat exchanger unit 16 a homogeneous fluidized bed is created, which is characterized by the heat exchanger unit 16 or the fluidized bed cells 20, 21 continues. There is extraordinary in this flight stream favorable conditions for heat transfer. On the way through the heat exchanger unit 16 is from the downward flowing brown coal evaporates hydrocarbon and the water content is reduced to approx. 10% residual moisture.

The driven hydro-steam KWD of all drying units 1-8 then gets into the steam collection chamber 22 and from there via outlet 26 for aftertreatment.

Excess steam can flow from the circulatory system to the Balance the mass balance to be taken to the pressure to keep constant in the drying units 1-8. Of the Excess steam can be used as heating steam HD or otherwise will.

Dried brown coal TBK is over the extraction units 14 deducted from the drying units 1-8. As the Figure 1 shows, a trigger unit 14 is two Drying units 1, 2; 3, 4; 5, 6; 7, 8 assigned.

The withdrawal takes place via a screw conveyor 89 with two oppositely aligned spiral sections 90, 91 and a rotary valve 92. The side walls 93, 94 of the trigger unit 14 are in the direction of the screw conveyor 89 inclined so that the dried brown coal TBK easily can flow to the screw conveyor 89.

The cellular wheel locks 92 of the individual extraction units 14 carry the dry lignite TBK on a discharge conveyor 95 from where the dry brown coal TBK to Further use in the power plant process is brought. Of the Discharge conveyor 95 extends below the drying units 1-8 in an encapsulated discharge space 96, which, if necessary, for inerting and / or cooling the Dry lignite TBK can be used.

To condense the hydro steam KWD to the Inner surfaces 97, 98 of the steam fluidized bed dryer unit 17 and the steam collection chamber 22 are to be avoided whose outer walls 99, 100 heatable. The deduction units are also 14 heatable.

List of reference symbols

1 -

Drying unit

2 -

Drying unit

3 -

Drying unit

4 -

Drying unit

5 -

Drying unit

6 -

Drying unit

7 -

Drying unit

8th -

Drying unit

9 -

Dryer line

10 -

group

11 -

group

12 -

group

13 -

group

14 -

Deduction unit

15 -

Nozzle base unit

16 -

Heat exchanger unit

17 -

Steam fluidized bed dryer unit

18 -

Task unit

19 -

partition wall

20 -

Fluidized bed cell

21 -

Fluidized bed cell

22 -

Steam collecting chamber

23 -

Installation

24 -

Grate floor unit

25 -

Angle profile

26 -

Outlet

27 -

bunker

28 -

Bunker funnel

29 -

Bunker funnel

30 -

Bunker funnel

31 -

Bunker funnel

32 -

Cell wheel lock

33 -

Cell wheel lock

34 -

Cell wheel lock

35 -

Cell wheel lock

36 -

Chain scraper conveyor

37 -

Chain scraper conveyor

38 -

Chain scraper conveyor

39 -

Chain scraper conveyor

40 -

Pre-treatment room

41 -

Discharge chute

42 -

Discharge chute

43 -

Floor v. 36

44 -

Floor v. 37

45 -

Floor v. 38

46 -

Floor v. 39

47 -

Discharge opening

47 '-

Discharge opening

47 ''

Discharge opening

47 '' '

Discharge opening

48 -

Discharge opening

48 '-

Discharge opening

48 ''

Discharge opening

48 '' '

Discharge opening

49 -

Slider

50 -

Slider

51 -

Slide drive

52 -

Slide drive

53 -

chamber

54 -

bunch

55 -

bunch

56 -

Heat exchanger tube

57 -

Heat exchanger tube

58 -

Length section

59 -

Length section

60 -

Vertical pipe section

61 -

Vertical pipe section

62 -

Tube sheet

63 -

Steam distribution chamber

64 -

Steam distribution chamber

65 -

Condensate collection chamber

66 -

Condensate collection chamber

67 -

Steam manifold

68 -

Distribution line

69 -

Deduction

70 -

Deduction

71 -

Rust nozzle bottom

72 -

Rust nozzle bottom

73 -

Nozzle pipe

74 -

Vortex medium ring line

75 -

Supply

76 -

Supply

77 -

Distribution line

78 -

Distribution line

79 -

jet

80 -

Support

81 -

cap

82 -

upper end of 80

83 -

Nozzle opening

84 -

Nozzle opening

85 -

Opening in 73

86 -

Cap wall

87 -

Annulus

88 -

Annular gap

89 -

Auger

90 -

Spiral section

91 -

Spiral section

92 -

Cell wheel lock

93 -

Sidewall v. 14

94 -

Sidewall v. 14

95 -

Deduction conveyor

96 -

Discharge area

97 -

Inner surface v. 17th

98 -

Inner surface v. 22

99 -

Outer wall v. 17th

100 -

Outer wall v. 22

FBK -

Wet brown coal

HD -

Heating steam

K -

condensate

KWD -

Hydro steam

TBK -

Dry lignite

World Cup -

Vortex medium

Claims (4)

Coal feeding device for a system for steam fluidized bed drying of broken raw lignite, which comprises at least two drying units (1-8), characterized in that at least one gas-tight metering device (32-35) and a conveyor (36-39) connected downstream thereof in a heatable Pretreatment room (40) above the drying units (1-8) are arranged, the raw lignite in the longitudinal direction of the conveyor (36-39) can be transferred to the drying units (1-8) in a quantity-adjustable manner. Coal feeding device according to claim 1, characterized in that the conveyor (36-39) has discharge openings (47, 48) which are adjustable in cross-section over its length. Coal feeding device according to claim 1 or 2, characterized in that discharge chutes (41, 42) are assigned to the conveyor 36-39). Coal feed device according to claim 3, characterized in that the drying units (1-8) are assigned a common steam collecting chamber (22) and the feed chutes (41, 42) the steam collecting chamber (22) for loading at least two vertically oriented fluidized bed cells (20, 21). as parts of a heat exchanger unit (16) which are divided by a partition (19).

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