AU2013265332B2 - Method for processing pit-moist raw brown coal - Google Patents
Method for processing pit-moist raw brown coal Download PDFInfo
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- AU2013265332B2 AU2013265332B2 AU2013265332A AU2013265332A AU2013265332B2 AU 2013265332 B2 AU2013265332 B2 AU 2013265332B2 AU 2013265332 A AU2013265332 A AU 2013265332A AU 2013265332 A AU2013265332 A AU 2013265332A AU 2013265332 B2 AU2013265332 B2 AU 2013265332B2
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- brown coal
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- dry
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B1/00—Preliminary treatment of solid materials or objects to facilitate drying, e.g. mixing or backmixing the materials to be dried with predominantly dry solids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2201/00—Pretreatment of solid fuel
- F23K2201/20—Drying
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
- F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
- F26B3/08—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed
- F26B3/084—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed with heat exchange taking place in the fluidised bed, e.g. combined direct and indirect heat exchange
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Drying Of Solid Materials (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
Abstract
The invention relates to a method for processing pit-moist raw brown coal, in particular for the thermal utilization in a power plant boiler. The raw brown coal is first precrushed and then comminuted in at least one milling appliance (2) and also fed to downstream drying. The drying proceeds in a fluidized bed using an indirectly heated fluidized-bed dryer (3). Some of the dry brown coal taken off from the fluidized-bed dryer (3) is branched off and added back to the raw brown coal before the drying, as a result of which the fluidizability of the brown coal is improved.
Description
m 2013/174828 - 1 PCT/EP2013/060437
Method for processing pit-moist raw brown coal 10
The invention relates to a process for the foenef iclation of pit-’tnoist raw brown coal, in particular for thermal utilization in a power station boiler, wherein the raw brown coal is firstly precrushed and subsequently comminuted in at least one milling apparatus and passed to subsequent drying and the drying is carried out in a fluidized bed using at least one indiirectly heated fluidized-bed dryer which is operated using steam as fluidization medium. A process for drying water-containing brown coal in a fluidized bed is knovm, for example, from 15
In the fluidized-bed drying process described there, the feed coal is introduced by means of a screiv conveyor into the fluidized-bed dryer. 20 25 30
The process known from the aboveraentioned document is said to be suitable for drying lumpy materials having a size in the range from, for example, 0.3 cm to 10 cm. For this purpose, the material to be dried, for example brown coal, is fluidized iii a denser material such as silica sand. The process requires that the dried solid material is removed together with part of the particulate fluidizable material and that the solid material and the fluidizable material are separated from one another so that the fluidizable material separated off is returned to the fluidized bed. The process is complicated and cannot be readily implemented in industry. 35 Another process for drying brown coal, in particular for use in a power station boiler, is known from, for DE 196 20 047 Ai. This process Is operated ο (Ν S' σ^ (Ν (Ν m m IT) Ό (Ν m ο (Ν using exclusively brown coal as solid and steam as fluidizing medium. The brown coal to be introduced into the dryer is comparatively finely milled, for example to an average particle diameter dso of about 1 mm, to enable it to be fluidized in the fluidized bed.
Depending on the nature of the brown coal, such a fluidized-bed drying process can proceed relatively stably and in a problem-free manner in a steady-state fluidized bed.
As has already been described in DE 29 01 723 C2, this depends essentially on the fluidizability of the solid in the fluidized-bed dryer. The hydromechanical processes within a steady-state fluidized bed are extremely complex and can be simulated to only a limited extent. In a pilot plant operated by the applicant, disturbances in the mixing dynamics have been found from time to time, depending on the mass flow to be introduced. As a result of such disturbances, deposits of raw brown coal are preferentially formed on the heat exchangers of the fluidized-bed dryer. As a result, heat transfer is impaired, the performance of the dryer decreases significantly and in the worst case the fluidized bed collapses.
Experiments using fluidized-bed dryers at a variety of throughputs have shown that the fluidizability of raw brown coal depends not only on the loading of the fluidized-bed dryer as a proportion of the capacity but also on the type and composition of the raw brown coal.
There is a need for a process for the beneficiation of pit-moist raw brown coal using at least one indirectly heated fluidized-bed dryer which ensures essentially stable and disturbance-free fluidized bed operation even at a high throughput and for a variety of feed coals.
It is an object of the present invention to at least substantially satisfy the above need.
The present invention provides a process for the beneficiation of pit-moist raw brown coal for thermal utilization in a power station boiler, wherein the raw brown coal is firstly precrushed and subsequently comminuted in at least one milling apparatus and passed to subsequent drying, where the drying is carried out in a fluidized bed using at least one indirectly heated fluidized-bed dryer which is operated using steam as fluidization medium, where the raw brown coal is introduced as bulk material having an average particle diameter dso of not more than 2 mm into the fluidized bed and a substream is branched off from the dried brown coal downstream of the fluidized-bed dryer and mixed into the raw brown coal before drying.
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(N m m Ό (N m H O (N wherein the proportion of recirculated dry brown coal is regulated as a function of the amount of raw brown coal introduced into the fluidized bed.
The particle size distribution can be ensured, for example, by variation of the speed of rotation of one or more of the mills located upstream of the fluidized-bed dryer. Mills employed are, for example, beater mills which achieve a different milling fineness as a function of the speed of rotation. The particle size distribution is checked by sieving and sampling can for this purpose be provided daily or even per batch. The samples are monitored in the laboratory by sieve classification. As an alternative, the particle size distribution can also be measured volumetrically by means of an on-line method.
To achieve stability of the fluidized bed, it is, first and foremost, important that the proportion of oversize particles (> 2 mm) is not too great since this could otherwise adversely affect the stability of the fluidized bed.
The particle size distribution can, as an alternative, also be ensured by milling of the dried brown coal being followed by sieve classification, with the oversize particles being sieved out and subjected to after-milling.
The present disclosure is based on the recognition that pit-moist raw brown coal has different cohesive behavior depending on its origin, and this has a more or less large influence on the fluidizability of the coal.
It is known that raw brown coal, as natural product obtained by mining, differs in respect of water content, proportion of carbon and mineral composition depending on its origin. Particular properties of the raw brown coal have to be accepted in use.
The applicant was able to discover experimentally that the fluidizability of the raw brown coal is closely related to its flowability and that the fiowability of the raw brown coal can surprisingly be positively influenced by mixing in dry brown coal of the same type.
According to embodiments of the invention, the same type of coal in the form of dry brown coal is accordingly added to the raw brown coal to be dried before the drying operation.
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The stability of the benefieiation proeess aeeording to embodiments of the invention, in partieular the stability of the fluidized bed within the fluidized-bed dryer, ean surprisingly be improved by part of the dried brown eoal being eireulated within the proeess, so that even raw brown eoal whieh is difficult to fluidize or cannot be fluidized can in this way be used and dried without problems with at the same time a comparatively high throughput through the fluidized-bed dryer.
The problem of fluidizability of the fluidized bed also depends on the loading of the fluidized-bed dryer as a proportion of capacity. Disturbances in the fluidized bed can, in particular, occur at a high loading of the fluidized-bed dryer as a proportion of capacity.
The mixture of raw brown coal and recirculated dry brown coal is, in the process according to embodiments of the invention, preferably fed via a star feeder into the fluidized-bed dryer which is under slightly superatmospheric pressure, introduced above the fluidized bed and distributed over the fluidized bed.
Particular preference is given to mixing a proportion of dry brown coal of from 10 to 30% by mass, preferably from 10 to 20% by mass, based on the total bed, into the raw brown coal.
The proportion of recirculated dry brown coal is preferably regulated as a function of the amount of raw brown coal introduced into the fluidized bed. Regulation can be effected by setting a particular ratio of dry brown coal to raw brown coal and metering in the dry brown coal accordingly. Depending on the plant loading set, the amount of recirculated dry brown coal can automatically be adapted at a constant ratio.
For the purposes of the present patent application, regulation is automatic regulation for which appropriate process control instrumentation is provided.
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The raw brown coal can have a fluctuating water content/moisture content of up to 65% by mass. The water content of the dry brown coal taken off from the fluidized-bed dryer is determined in the hygroscopic range at constant system pressure by means of the fluidized-bed temperature or the course of the desorption isobars. The dry brown coal taken off from the fluidized-bed dryer can have an average particle diameter dso of from 0.4 mm to 0.8 mm, preferably from 0.1 mm to 0.4 mm, possibly also from 0.1 mm to 0.2 mm. The moisture content of the dry brown coal can be in the range from 10% by mass to 15% by mass, preferably about 15% by mass - 18% by mass. The gauge pressure within the fluidized-bed dryer can be up to 10 bar. The moisture content of the dry brown coal can also be in the range from 8 to 20% by mass, preferably from 10 to 16% by mass.
As mentioned above, the fluidized-bed dryer is preferably indirectly heated by means of steam as heating medium. Part of the vapor from the dryer or alternatively external steam from a coupled power station process can be used for fluidizing the fluidized bed or the raw brown coal within the fluidized-bed dryer.
The dry brown coal which has been branched off can be intimately mixed with the raw brown coal using at least one mixing apparatus before introduction into the fluidized-bed dryer. Such mixing is not necessary under all circumstances, but significantly improves the adhesion of fine dry coal particles to the particles of the moist raw brown coal used.
For example, the dry brown coal can be cooled downstream of the fluidized-bed dryer and subjected to after-milling, with a substream of dry brown coal being branched off downstream of after-milling.
It is of course also possible to branch off the dry brown coal to be recirculated directly downstream of the fluidized-bed dryer, but cooling and after-milling is preferable, so that, for example, the dry brown coal having an average particle size dso of from 0 mm to 1 mm is added to the raw brown coal. The particle size distribution can likewise be determined volumetrically by sieve classification, and the after-milling can be carried out accordingly in the case of a deviating particle size distribution.
AH26(13047863_2):JBL ο (N δ-
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The recirculated dry brown coal can be mixed into the raw brown coal between two milling stages or downstream of a last milling stage. Of course, it is also possible to add the recirculated dry brown coal to the raw brown coal before a first milling.
In this case, intimate mixing is ensured simply by joint milling of raw brown coal and dry brown coal, so that separate mixing apparatuses may be dispensable. However, for a relatively effective and energy-efficient process, it is good practice to circulate as little as possible dry brown coal and to keep the path of the dry brown coal to be recirculated or conveyed concomitantly as short as possible. However, the point of view of explosion protection should also be taken into account. For the latter reason, it is preferable and sensible to add the recirculated dry brown coal to the raw brown coal downstream of fine milling of the raw brown coal and carry out mixing with the raw brown coal, for example by means of static or dynamic mixing apparatuses, in the feed line to the fluidized-bed dryer. Mixing can, for example, also be carried out via a conventional transport apparatus.
It is preferable for the proportion of dry brown coal mixed into the raw brown coal to be varied as a function of the adhesion properties of the raw brown coal and/or the loading state of the fluidized-bed dryer. As will be again stated below, it has been found that the flow properties and the adhesion properties of raw brown coal depend to a significant extent on the compressibility of the raw brown coal and thus on the bulk density of the raw brown coal in the compacted state.
The pouring of the raw brown coal into the fluidized bed is preferably carried out by means of at least one rotating distributor chute arranged above the fluidized bed, preferably according to a prescribed distribution based on the cross-sectional area of the fluidized-bed dryer.
AH26(13047863_2):JBL ο Ο (Ν δ' σ^ (Ν (Ν m Ό (Ν m ο (Ν A preferred embodiment of the invention will be described hereinafter, by way of example only, with reference to the accompanying drawings, wherein: The figures show: figure 1: a schematic depiction of the process principle of the beneficiation process according to the invention, and figure 2: a graph in which the bulk material strength of materials of differing flowability is shown as a function of the consolidation stress. Reference will firstly be made to the process principle depicted in figure 1, which illustrates the flow diagram of a fluidized-bed drying plant which can be connected, for example, to a power station boiler for firing with brown coal. From an open-cast brown coal mine, precrushed raw brown coal having an average particle size of from 0 mm to 80 mm is, for example, fed into a raw brown coal hopper 1. From the raw brown coal hopper 1, the raw brown coal is finely milled to an average particle size (dso) of about 0 mm - 2 mm in two mills arranged in series. The raw brown coal is then mixed with dry brown coal, as described further below, and introduced into a fluidized-bed dryer 3. The fluidized-bed dryer 3 is.
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AH26(13047863_2):JBL ΡΟΤ/ΕΡ2013/06 0437 wo 2013/174828 for example, heated indirectly by means of steam via appropriate heat-exchange internals. The steam feed to supply the heat exchanger is denoted by the reference symbol 4 in the process diagram (fig. 1) . The 5 fluidized-bed dryer 3 is operated in a known way under slightly superatraospheric pressure, with the raw brown coal being introduced into the fluidized bed via a star feeder which is not shown and via a distributor chute arranged in the upper part Of the fluid!zed-bed dryer 10 3. The vapor 5 taken off from the fluidized-bed dryer 3 is, after removal of dust in an electrostatic precipitator 6, passed to various other uses. It can, for exatTiple,, be x'eleased into the atmosphere. As an alternative, it can be condensed, with the low- 15 temperature heat from the condensation of the vapor being, for example, integrated into the boiler feed water preheating of a power station process. In a further alternative, the vapor can be compressed and fed back into the fluidized-bed dryer 3 for the purpose 20 of heating. The energy from the vapor can also be integrated into an ORC (organic rankine cycle) process. A substreara 7 of the vapor 5 is in any case fed as fluidizing medium to the fluidized-bed dryex" 3. The dry 25 brown coal 8 taken off from the fluidized-bed dryer 3 is firstly cooled in a cooler B and then after-milled in a mill 10 and fed into a dry brown coal silo 11. Possible places for taking dry brown coal off from the brown coal stream intended for thermal utilization are 30 denoted by El to E4, where El denotes an offtake point downstream of the fluidized-bed dryer 3 and upstream of the cooler 9, E2 denotes an offtake point downstream of the cooler 9 and upstream of the mill 10, E3 denotes an offtake point downstream of a mill IQ and upstream of 35 the dry brown coal silo 11. Finally, E4 denotes an offtake poi.nt downstream of the dry brown coal silo 11.
The substream of dry brown coal to be reeirGUlated is preferably taken off at E4, since because of the storage provided in the dry brown coal silo 11, better meterability of the substr^^ti to be recirculated is ensured,
The dry brovm coal silo 11 can be provided at the discharge end with a discharge star feeder which can be operated at a variable speed of rotation. The speed of rotation control of the discharge star feeder enables 10 the amount of dry brown coal to be metered so that it is possible to set a ratio of amount of dry brown coal recirculated to the amount of raw brown coal as a function of the cohesivity of the raw brown coal and/or as a function of the load as a: proportion of capacity 15 or the load state: of the fluidized-bed dryer 3, The dry brown coal silo 11 can have two separate dry brown coal offtakes, of which one is provided for dry brown coal recirculation or dry brown coal baekmlxing while the other is the offtake for dry brown coal as usable 20 product of the drying process. The use of two separate offtakes has, in particular, the advantage in terras of regulation that the sAibsequent transport path can also be used for filling the fluidized-bed dryer 3 with dry brown coal before start-up. Before a first introduction the fluidized-bed 25 of raw brown coal on start-up ;s cohesive dryer 3, it is necessary firstly to build up a fluidized bed by raeans of dry brown coal 8 since the raw coal is not fluidizable because of properties. 3 0 35 wo 2013/174828 - 10 - PCT/EP2013/O60437 A further advantage of such an ax'rangement is that should the raw coal feed fail, dry brown coal recirculation can corapensate for the discharge of dust from the fluidized bed and the fluidized bed and all control circuits of the fluidized-bed dryer can continue to be operated normally.
The positions R1 to R4 denote possible recirculation poixits for the dry brown coal to be recirctilated, where the recirculation: point R1 is provided dire:Ctly downstream of the raw coal hopper 1, the recirculation point R2 is provided between a first mill and a second mill, and the: recirculation point R3 is provided dovmstream of a second mill and upstream of the fluidized-bed dryer 3. The recirculation point R4 is provided directly upstream of the fluidized-bed dryer 3. 10 15 wo 203,3/174828 11 PCT/EP2013/060437
The applicant has surprisingly found that the flowabillty of various raw coals is directly related to their fluidizability in the fluidized bed. Mixing dry brown coal into the raw brown coal which is difficult to fluidize enables the flowabillty of the raw brown coal to be introduced into the drying process to be s i gni f i cantly improved.
To demonstrate this relationship, the applicant has 20 examined various raw brora coals from various open-cast mines and also each dry brown coal obtained from these raw coals in respect of their f low properties. The various coal samples, designated below as samples 1 to 5 in the interests of simplicity, and the dry brown 25 coals obtained therefrom, designated below as TBK 1 to TBK 5, were each subjected to flowability tests, with a flowabillty being determined as ratio of a consolidation stress to a compressive stress. The: flowability is given by;:: 30 ffc = O], to Oc, where ffo is the flowability, oi is the consolidation stress and Oc is the compressive streiagth, Such a flowability can be determined both by means of the known single “axis pressure: test and by means , of 35 commercially available ring shear instruments. Such a ring shear instrument is commercially available from, for example, the company Dr. bietmar Schulze
Sohuttg'Utmesstechnik (ring shear instrument ST-XS) . - 12 - PCT/EP2013/060437 wo 2D13/174828 Various other available. of ring shear instruments are
The flowability of bulk material can be classified as follows: ffc < 1 non-flowing 1 < ffc < 2 very cohesive to non-flowing 2 < ffc < 4 cohesive 10 15 20 4 < ffc < 10 readily flowing 10 < ffc free-flowing.
The hulk material strength Cc as a function of the consolidation stress στ. for regions of different flowability is shown by way of example in figure 2.
The samples examined by the applicant were examined at a temperatui'e of about 19at an atmospheric humidity of about 30% relative humidity. The result of the flowability measurements is shown below in table 1, where Oc denotes the bulk material strength or compressive strength of the bulk material after it has been compacted under the stress Oi, ffc is the ratio of oi to Oc, pb in kg/m^ is the bulk material density, pe is the measure of the internal friction angle of the bulk material in the case of steady-state flow, φϋϋ is the gradient angle of the linearised flow location approximated as a straight line and is the internal friction angle in steady-state flow. 30
Table 1:
Sample [PeJ Oc [Pa] ffc [-] Pb [kg/mh 1 4020 1703 2.4 530 48 37 40 2 40S7 2320 1.8 501 53 36 42 3 3890 1946 2.0 504 49 35 40 4 4443 2007 2.2 554 49 37 42 5 4104 2096 2.0 S29 50 35 41 10
In the case of the raw brown coal samples 1 to 5, the flowability ffc in table 1 is from 1,8 to 2,4 for the consolidation stress studied. The samples without influence, of consolidation over time can thus be classified as cohesive to: very cohesive. The most unfavorable flowability is in the case of sample 2, while the most favorable flowability is obtained for sample 1: based on the bulk material: strength Cc of sample 1, sample 2 has a strength which is greater by
As regards the dry brown coal,: samples 6 to 10, the flowability of the di-y brown coal is significantly 15 better than that of; the raw brown coal. 20 TBK from 1 4219 5X4 8.2 543 41 38 38 TBK from 2 4109 5X4 8.0 604 44 41 39 TBK from 3 4192 403 XO . 4 574 40 38 38 TBK from 4 4022 524 7.7 650 40 37 37 TBK from: 5 4243 S34 7.9 607 42: 39 39 WG 2013/174828 - 13 PCT/EP2013/0 604 37
The raw browffl coal sample 2 displays the most unfavoidable flow properties. ¥arious proportions of the dry brown coal TBK 2 (dry brown coal from sample 2) were then mixed in proportions by weight of 5%, 10%, 15% and 20% into the raw brown coal sample 2. The mixture was then examined to determine its flowability, and the raeasurement result is shown in table 2. 25 Table 2:
Proportion of TBK Οχ [Pa] o« [?a] ffc [-1 Pb me ["] <PiiT>. t“3 'Psf id 0% 4067 2320 1.8 501 53 36 42 5% 3780 2148 1.8 502 51 33 39 10% 3935 X923 2.0 511 48 33 39 15% 3780 1650 2.3 ,519 47 35 38 wo 2013/174828 PCT/EP2 013/060 43 7 20% 1 3758 1 1356 2.8 523; 43 33 37 100% 4109 1 514 8.0 604 44 41 39 - 14 -
The bulk density v;as determined both in the uncompacted loose state and after consolidation under a stress of about 4 kPa (values from table 1) , The bulk density both in the uncompaeted state and in the consolidated state of the sample is shown in table 3 below both for the samples 1 to S and for the samples TBK 1 to TBK 5 and also for various mixtures. 10 10
Table 3: Sample Bulk density Pb [kg/m^1 at a consolidation stress of ~> 0 kPa approx. 4 kPa 1 433 53 0 2 380 5 01 3 410 504 4 467 554 5 447 529 TBK from 1 453: 453 TBK from 2 603 604 TBK from 3 574: 574 TBK from 4 640 650 TBK from 5 604 607 2 + 0% of TBK 380 501 2 + 5% Of TBK 380 502 2 4- 1Q% of TBK 400 511 2 + 15% of TBK 410 519 2 + 20% of TBK 429 523 100% of TBK 603 604 W© 2013/174828 IS - Ρ€Τ/ΕΡ2013/060437
Sample 2 has a particularly low bulk density. This corresponds with the unfavorable flowability for this sample, as is indicated in table i. If a bulk material has an unfavorable flowability, the individual particles are not mobile in the bed, so that voids remain and the bulk density is low. As a consequence, the samples are compressible and the bulk density therefore depends on the stress applied. The greatest compressibility is likewise found in the case of sample 2.
The dry brown coals also differ appreciably in terms of 15 the bulk density. However, no relationship is foiind betw'een the raw brown coals and the dry brown coals: a wo 2013/174828 16 PCT/EP2 013/0604 37 low bulk density of the raw brown coal does not necessarily mean a low bulk density of the dry brown coal. The dry brown coals are only very slightly to Ttieasurably corapressible in the consolidatiori stress range studied.
Both the uncompacted bulk density and the bulk density under a consolidation stress of about 4 kPa increase with increasing proportion of dry brown coal. This can 10 be explained by the: better flowability after addition of the dry brown coal in that a more favorable flowability allows closer packing with a smaller proportion of voids and thus a higher bulk density:. 15 In conclusion, it can be: said that mixing in of dry brown coal, for example into sample 2, has a favorable effect on the flowability of the mixture. wo 2013/174828 - 17 - PCT/SP2013/060437
Reference syiribols 1 2 Raw brown coal hopper Mills 3 Fluidized-bed dryer 4 Steam feed 5 Vapor 6 Electrostatic filter 7 Substream of the vapor 8 Dry bro'wn coal 9 Cooler 10 Mill 11 Dry brown coal silo El - E4 Offtake points for dry brown coal R1 - R4 Recycle points for diry brown coal
Claims (10)
1. A process for the beneficiation of pit-moist raw brown coal for thermal utilization in a power station boiler, wherein the raw brown coal is firstly precrushed and subsequently comminuted in at least one milling apparatus and passed to subsequent drying, where the drying is carried out in a fluidized bed using at least one indirectly heated fluidized-bed dryer which is operated using steam as fluidization medium, where the raw brown coal is introduced as bulk material having an average particle diameter d^o of not more than 2 mm into the fluidized bed and a substream is branched off from the dried brown coal downstream of the fluidized-bed dryer and mixed into the raw brown coal before drying, wherein a proportion of recirculated dry brown coal is regulated as a function of the amount of raw brown coal introduced into the fluidized bed.
2. The process as claimed in claim 1, wherein a proportion of recirculated dry brown coal in the range from 10% by mass to 30% by mass, based on the total bed, is mixed into the raw brown coal.
3. The process as claimed in claim 1, wherein a proportion of recirculated dry brown coal in the range from 10% by mass to 20% by mass, based on the total bed, is mixed into the raw brown coal.
4. The process as claimed in any one of claims 1 to 3, wherein the dry brown coal branched off is intimately mixed with the raw brown coal using at least one mixing apparatus before production into the fluidized-bed dryer.
5. The process as claimed in any one of claims 1 to 4, wherein the dry brown coal is cooled and subjected to after-milling downstream of the fluidized-bed dryer, and the substream of the dry brown coal to be recirculated is branched off downstream of the after-milling.
6. The process as claimed in any one of claims 1 to 5, wherein the dry brown coal is mixed into the raw brown coal between two milling stages or downstream of a last milling stage.
7. The process as claimed in any one of claims 1 to 6, wherein mixing of raw brown coal and dry brown coal is carried out using at least one static mixing apparatus in a bulk material feed line to the fluidized-bed dryer.
8. The process as claimed in any one of claims 1 to 7, wherein the proportion of recirculated dry brown coal mixed into the raw brown coal is varied as a function of the adhesion properties and/or the bulk density of the raw brown coal in the compacted state.
9. The process as claimed in any one of claims 1 to 8, wherein the raw brown coal is poured into the fluidized bed by means of at least one rotating distributor chute arranged above the fluidized bed.
10. The process as claimed in claim 9, wherein the raw brown coal is poured into the fluidized bed according to a prescribed distribution based on the cross-sectional area of the fluidized-bed dryer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102012010078.7 | 2012-05-23 | ||
| DE102012010078A DE102012010078A1 (en) | 2012-05-23 | 2012-05-23 | Process for the treatment of gruel wet lignite |
| PCT/EP2013/060437 WO2013174828A1 (en) | 2012-05-23 | 2013-05-22 | Method for processing pit-moist raw brown coal |
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| AU2013265332A1 AU2013265332A1 (en) | 2014-12-04 |
| AU2013265332B2 true AU2013265332B2 (en) | 2017-06-29 |
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| EP (1) | EP2852799B1 (en) |
| CN (1) | CN104334989B (en) |
| AU (1) | AU2013265332B2 (en) |
| CA (1) | CA2872454C (en) |
| DE (1) | DE102012010078A1 (en) |
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| CN103880261B (en) * | 2014-03-18 | 2015-11-18 | 嘉兴绿方舟环保技术有限公司 | A kind of circulating fluidized bed air drying system |
| CN105157353A (en) * | 2015-03-06 | 2015-12-16 | 中昊晨光化工研究院有限公司 | PTFE suspension resin drying system and method |
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| DE102010003612A1 (en) * | 2010-04-01 | 2011-10-06 | Brandenburgische Technische Universität Cottbus | Method and apparatus for drying coal |
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| JPS5458601A (en) * | 1977-10-20 | 1979-05-11 | Nagata Seisakusho Co Ltd | Drying of lignite |
| AU4296978A (en) | 1978-02-10 | 1979-08-16 | Monash University | Drying particulate materials |
| JPS5782682A (en) * | 1980-09-17 | 1982-05-24 | Still Carl Gmbh Co Kg | Method of and apparatus for indirectly drying and preheating granular material |
| DD244044A3 (en) * | 1982-12-06 | 1987-03-25 | Bkw Geiseltal Veb | METHOD FOR THE TREATMENT OF SURFACE MOISTURIZED RAW BROWN COAL |
| DD232338A1 (en) * | 1984-08-28 | 1986-01-22 | Orgreb Inst Kraftwerke | METHOD AND ARRANGEMENT FOR PREPARING SOLID MOISTURE FUELS |
| DD264970A1 (en) * | 1987-11-24 | 1989-02-15 | Orgreb Inst Kraftwerke | PROCESS FOR BETTER MIXING OF SURFACE MOISTURE PACKAGING INTO A SWIVEL LAYER |
| DD279937B5 (en) * | 1989-02-06 | 1993-08-19 | Ver Energiewerke Ag | DEVICE FOR DRYING, GRINDING AND BURNING BALLASTIC FUELS |
| DE4409056C2 (en) * | 1994-03-11 | 1998-03-26 | Ver Energiewerke Ag | Method and arrangement for pre-drying broken raw lignite for a pressure-charged fluidized bed furnace |
| DE19612187C2 (en) * | 1996-03-27 | 2001-11-15 | Bbp Energy Gmbh | Process for crushing and drying brown coal |
| DE19618880C2 (en) * | 1996-05-10 | 2001-12-13 | Rheinische Braunkohlenw Ag | Process for processing lignite |
| DE19620047C2 (en) | 1996-05-18 | 2002-06-27 | Rwe Rheinbraun Ag | Method and device for drying lignite |
| CN2494964Y (en) * | 2001-08-11 | 2002-06-12 | 哈尔滨工业大学达通热能工程有限公司 | Full-automatic high-moisture raw coal fluidized bed dryer |
| DE102007002631A1 (en) * | 2007-01-12 | 2008-07-17 | Rwe Power Ag | Small-scale fuel from lignite and process for its production |
| WO2010057512A1 (en) * | 2008-11-24 | 2010-05-27 | Rwe Power Aktiengesellschaft | Method for preparing brown coal |
| CN101581533B (en) * | 2009-06-04 | 2010-10-06 | 山东天力干燥设备有限公司 | Device for pre-drying lignite through overheated steam and process thereof |
| DE102010003613A1 (en) * | 2010-04-01 | 2011-10-06 | Brandenburgische Technische Universität Cottbus | Method and apparatus for drying coal |
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| CN102353237B (en) * | 2011-08-18 | 2013-12-11 | 西安交通大学 | High-moisture-content lignite predrying method and system integrated with thermal power plant |
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2012
- 2012-05-23 DE DE102012010078A patent/DE102012010078A1/en not_active Withdrawn
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2013
- 2013-05-22 EP EP13724262.4A patent/EP2852799B1/en not_active Not-in-force
- 2013-05-22 WO PCT/EP2013/060437 patent/WO2013174828A1/en active Application Filing
- 2013-05-22 CN CN201380026540.0A patent/CN104334989B/en not_active Expired - Fee Related
- 2013-05-22 CA CA2872454A patent/CA2872454C/en not_active Expired - Fee Related
- 2013-05-22 AU AU2013265332A patent/AU2013265332B2/en not_active Ceased
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102010003612A1 (en) * | 2010-04-01 | 2011-10-06 | Brandenburgische Technische Universität Cottbus | Method and apparatus for drying coal |
Also Published As
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|---|---|
| WO2013174828A1 (en) | 2013-11-28 |
| CN104334989A (en) | 2015-02-04 |
| CA2872454A1 (en) | 2013-11-28 |
| CA2872454C (en) | 2019-10-08 |
| EP2852799B1 (en) | 2018-11-21 |
| AU2013265332A1 (en) | 2014-12-04 |
| EP2852799A1 (en) | 2015-04-01 |
| DE102012010078A1 (en) | 2013-11-28 |
| CN104334989B (en) | 2016-08-17 |
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