EP3132198A1

EP3132198A1 - Method and device for drying wet, carbon-containing particulate fuel

Info

Publication number: EP3132198A1
Application number: EP15712276.3A
Authority: EP
Inventors: Torsten Buddenberg; Christian Bergins; Emmanouil KAKARAS
Original assignee: Mitsubishi Hitachi Power Systems Europe GmbH
Current assignee: Mitsubishi Power Europe GmbH
Priority date: 2014-04-16
Filing date: 2015-03-12
Publication date: 2017-02-22
Also published as: DE102014105477A1; AU2015246271A1; DE102014105477B4; WO2015158476A1

Abstract

In a method for drying, in a drying installation (12) of a power plant (16), wet, carbon-containing particulate fuel (14) which is to be fired in burners of a steam generator of the power plant (16), wherein the drying installation (12) is supplied with a temperature-controlled gas flow and the fuel (14) is dried in the drying installation (12) by means of heat energy transferred from the temperature-controlled gas flow, and the dried fuel (2) is supplied to burners of the steam generator, wherein at least a part of the flue gas flow is branched off as temperature -controlled flue gas flow in a flue gas part flow supply line (11, 11', 11'') which branches off from the flue gas line (6) and is supplied to the drying installation (12) arranged in the chain of the flue gas part flow supply line (11, 11', 11''), a solution is to be achieved which provides a method for drying wet, carbon-containing particulate fuel, which permits the drying of wet, carbon-containing particulate fuel in an energetically efficient and cost-effective manner. This is achieved by the fact that the heat energy of the temperature-controlled flue gas flow in the drying installation (12) is transferred at least in part to the fuel (14) to be dried and the temperature-controlled flue gas flow is returned to the flue gas flow via the flue gas part flow supply line (11, 11', 11'') which discharges back into the flue gas line (6).

Description

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The invention is directed to a method for drying in dampers of a combustion chamber or a steam generator of a power plant, preferably lignite power plant, especially dry lignite power plant, and / or a furnace to be fired damp, carbonaceous and particulate in a drying device and / or drying plant of the power plant, said the drying device and / or drying system fed a tempered gas stream and dried the fuel in the drying device and / or drying plant by means of the tempered gas stream and / or decoupled from this heat energy and the dried fuel a storage container and / or burners of the combustion chamber or the steam generator Power plant and / or the furnace is supplied, wherein in the combustion chamber or the steam generator and / or, in particular separate, firing system by combustion of fuel a Rauchgasstro m generated and this exhaust side in the flue gas flow direction downstream and outside the combustion chamber or the steam generator or the furnace is transferred to a flue gas line, and branched off at least a portion of the flue gas stream as tempered flue gas stream in a branching off from the flue gas line flue gas partial flow supply line and arranged in the strand of the flue gas partial flow supply line drying device and / or drying plant is supplied. Furthermore, the invention is directed to a fuel drying plant for carrying out the above method comprising a drying device and / or drying plant with a Brennstoffzuführleitung by means of which the drying device and / or drying plant moist, carbonaceous and particulate fuel can be supplied, and with a Brennstoffabführleitung, by means of which in the Drying device and / or drying system dried fuel to a storage container and / or burners a combustion chamber or a steam generator of a power plant, preferably a brown coal power plant, in particular a dry lignite power plant, and / or a firing system can be fed, wherein the drying device and / or Drying system with a line formed on the exhaust side of the combustion chamber or the steam generator or, in particular separate, furnace and / or their respective burners flue gas line and guided in the flue gas line flue gas in the form of a tempered flue gas stream for drying the wet fuel fed and in particular in the Drying device and / or Trocknungsaniage is initiated,

Crude lignite, but also biomass, has in its recovery state a relatively high moisture content, which may include water contents of over 50 wt .-% and up to 70 wt .-%. Since raw lignite and biomass in this state can not be useful as a fuel in Feuerungsaniagen, especially in combustion chambers of power plants, can be used, it is known raw lignite, but also mixtures of lignite coal and biomass, before the increase in price to an acceptable moisture content, that is an acceptable Water content, to dry.

From the state of the art known and used in practice usually is at large power plants, especially lignite power plants, the Mahitrocknung and so-called raw lignite combustion (RBK firing). In this process, the drying of the wet fuel and its grinding are an integrated, process engineering process. To grind the fuel Schiagradmühlen, optionally with an upstream Vorschlägerstufe used. In such impact wheel mills, the grind-to-drying fuel, usually lignite coal, extracted from the combustion chamber of the fired with this fuel steam boiler power plant, about 1000 ° C hot flue gas as a carrier gas in the beater wheel and through this promoted. In the mill, both the grinding and crushing of the fuel, as well as its drying takes place. Subsequently, the dried fuel is then usually fed directly to the combustion chamber of the steam generator of the power plant, but in recent times also so-called indirect firing be used, in which the ground and dried fuel is first stored in a bunker or silo. Since the usual direct firing during the grinding drying process by means of a mill, in particular beater mill, leads to the transport of the fuel to the burners of the combustion chamber of the steam generator causing fan function of the mill always requires a certain minimum speed of the mill, the coal flow can only partially regulate with such a mill. As a result, a power regulation of the burners resulting from the fuel supply, in particular in low load ranges of the steam generator, is insufficiently feasible. In addition, the reaction times of the steam generator are insufficient in preceding Mahltrocknung. It always takes a certain time and delay until either the upstream mills are shut down at a desired power reduction or ramped up at a desired power increase and thus the required mass flow of fuel is adjusted to the desired performance. For this reason, the indirect firing systems have been developed in which the meal-dried fuel is stored in silos, from which the burners can then be supplied directly with a fuel mass flow or in the shutdown or shutdown of Brennermassestromes, the upstream mills for one certain Zettraum can feed meal-dried fuel.

While the above-described grinding drying methods are dried with a flue gas having a temperature of approximately 1000 ° C., as an alternative to this, drying methods are also known from the prior art according to practice, in which the wet fuel with the aid of a merely tempered gas stream in a low-temperature heat range of <300 ° C. is dried. In these processes, the fuel drying takes place independently of the milling process in a separate from a grinding unit and in particular procedurally separate drying plant. That is, the drying plant does not include an integrated grinding process. As a tempered gas stream here is usually water vapor use. In the field of lignite combustion is then called a dry lignite furnace (TBK firing) when lignite fuel is used, the grinding process is independent or dried separately from the grinding process and then the furnace, or the burners of the combustion chamber of a steam generator is supplied. Such drying plants are, for example, the steam fluidized bed drying (DWT drying), the fluidized bed drying with internal waste heat recovery (WTA- Drying), pressurized steam fluidized bed drying (DDWT drying) or convective low-temperature drying with air. In steam fluidized-bed drying, the heat input required for drying takes place via pipelines embedded in a fuel fluidized bed, through which steam flows as heat transfer medium. In order to achieve a sufficiently high heat flux density, the temperature of the steam must be at least 40 ° C - 50 ° C above that of the fluidized bed. In the WTA drying, the amount of steam required for the formation of the fluidized bed is additionally compressed after leaving the fluidized bed and then used for heating the fluidized bed or incorporated into the heat flow of the connected power plant. While DWT drying and WTA drying are carried out under atmospheric conditions, DDWT drying takes place at a system pressure increased up to 6 bar. While DWT, WTA and DDWT drying are based on indirect heat transfer by steam, Lehigh University's Bethighhem, Pennsylvania, U.S.A. Lehigh Energy Update, "Research Demonstrates Benefits of Drying Western Coal, Vol. 20 (2), 2002 "and" Use of coal drying to reduce water consumption in powdered coal power plants ", Final Report, December 2, 2002 to March 31, 2006, by Edward K. Levy, Nenad Sarunac, Harun Bilirgen, Hugo Caram, DOE Award Number DE-FC26- 03NT41729, discloses the drying of wet fuel to raw brown coal by convective air drying. Described herein is the energy required for drying from a heated to about 43 ° C (110 ° F) air flow, which is introduced as a carrier gas for fluidized bed formation in a fluidized bed system and here transmits the required for the drying of the wet fuel energy to the wet fuel to provide. It is also described to heat the air by means of a countercurrently flowed from a power plant steam boiler flue gas and arranged in the flue gas line Luftvorwärmers to higher temperatures than 43 ° C and then the heated air for drying moist brown coal as a carrier gas by a power plant boiler lignite as fuel pass through the feeding coal grinder.

Since in these drying systems, which partially have a drying process which is separate from a fuel grinding process, the drying process can be decoupled from the grinding process in terms of process technology Process, the possibility to perform the drying at a lower temperature level exergetic efficient and optimize as a separate process step. A disadvantage of these known drying methods, however, is that in the convective drying by means of air there is the danger of explosions. If, for example, lignite is dried, compliance with only a low oxygen content in the drying gas must be ensured in order to avoid the danger of explosion. The other such drying methods, in which the fuel to be dried is heated directly or indirectly with steam, require a complicated control and regulation technique, which is suitable for the supply of a suitable vapor, and in particular also require the steam generation itself. This is associated with a high energy consumption.

A generic method and a generic fuel drying system disclosed in DE 10 2011 110 218 A1. In the method described in this document at least a portion of the flue gas is guided behind a regenerative air preheater via a flue gas duct. In one embodiment of this Rauchgaskanai consists of a first train and a second train. In the second train, a flue gas lignite heat exchanger is formed. In addition, the first train of the flue gas duct is designed as a large-capacity direct drying chamber, is dried in the preheated brown coal in direct contact with the flue gas. Here, from a lignite heat storage 1 1 the optionally dried in brown coal preheating 8 brown coal is fed to the first train 1a. The dried brown coal is used in a steam generator.

DE 10 13 824 A discloses a boiler and a mahit drying plant whose discharge is supplied via lines and a separator from which the ground and dried lignite is then transferred to a dust bunker. During the mill, flue gas taken directly from the combustion chamber is conveyed via a line in the usual way In addition, a drying in a riser, which is supplied in addition to the Mühlenaustrag via a line the rest of the exhaust gas of the boiler Furthermore, it is stated that the supplied gas via the line gives off its heat on the pre-dried fuel dust on the way through the riser and dry it to the value needed for the 4

6

Separation in the separator and the storage of dust in the bunker can be allowed.

DE 10 2011 110 218 A1 and DE 10 13 824 A have the disadvantage that the drying is carried out here with the hot exhaust gases of the combustion chamber.

DE 198 06 917 A1 discloses a method for drying fuel in which heat energy is decoupled from the exhaust gas flow of a boiler and coupled into a heating circuit, from which coal is then dried in a drying device with coupled-out heat. The in DE 196

06 917 A1 disclosed embodiment has the disadvantage that here for heating the wet lignite with the help of the flue gas decoupled heat energy, a double coupling / coupling of heat is necessary, namely once the extraction of heat from the flue gas in the water cycle and then the decoupling from the water cycle into the fuel stream.

A likewise prior art discloses the DD 241 461 A This document is the measure to divert from a flue gas line of the steam generator a flue gas partial flow supply line and supply by means of this flue gas a convection dryer 9. In the convection dryer wet Rohbraunsiebkohle is supplied and discharged as dried Rohbraunsiebkohle. The flue gas leaving the steam generator with a temperature between 200 ° C and 300 ° C is returned to the combustion chamber of the steam generator after passing through the ready-made dryer as a flue gas-vapor mixture at a temperature of 100 ° C via a corresponding line and a Einblasevorrichtung.

The embodiment according to DD 241 461 has the disadvantage that the flue gas / vapor mixture formed there in the convection dryer leads to an injection of water vapor into the combustion chamber, which is not necessarily desired. The invention has for its object to provide a solution that provides a method for drying of moist, carbonaceous and particulate fuel and a fuel drying plant, which the drying of moist, carbonaceous and particulate fuel in an energy efficient and cost-effective manner and in particular allow an advantageous integration of such a fuel drying plant, even after upgradable, in a power plant.

To achieve this object, the invention proposes a fuel drying method according to claim 1 and a fuel drying system according to claim 22. Advantageous embodiments and expedient developments of the invention are

Subject of the respective subclaims.

In a method of the type described in more detail, the above object is achieved in that the thermal energy of the tempered flue gas stream is at least partially transmitted to the drying fuel in the drying device and / or drying system and the tempered flue gas flow through the back into the flue gas line flue gas partial flow supply line is returned to the flue gas stream.

In a fuel drying system of the type described in more detail above, the above object is achieved in that the drying device and / or drying plant is arranged in the branch of a branching off of the flue gas line and re-opening into the flue gas line flue gas partial flow supply line.

The fact that in a branched off from the flue gas line flue gas partial flow supply line a tempered flue gas partial flow to the drying device and / or drying system, here heat energy of the tempered flue gas stream delivered to the fuel to be dried and then cooled tempered flue gas sub-stream then re-entering the flue gas line flue gas partial flow supply line in the Flue gas flow is recycled, is an energetically efficient and cost-effective way of integrating a fuel drying plant in a 4

8th

Power plant realized. Since the flue gas partial flow supply line branches off the flue gas stream downstream and downstream of the combustion chamber or the steam generator, it no longer has the high temperature which would have a flue gas flow branched off directly from the combustion chamber. In addition, the diversion can also take place after passing through one or more flue gas treatment facilities / flue gas treatment plants, so that even a further cooling treatment can be present here.

Furthermore, only a heat extraction Wärmeeinkopplungs process is necessary by the inventive design, namely the heat extraction from the Rauchgasteiistrom in the fuel. This can even be convective, d. H. by direct contact of tempered flue gas and fuel. Finally, the branched Rauchgasteiistrom then also returned to the flue gas line and thus supplied to the flue gas main stream and discharged after appropriate exhaust treatment with this in the environment. There is no return of the branched flue gas partial stream into the combustion chamber or the steam generator of the power plant instead.

With the invention it is possible to use a Rauchgasteiistrom, which is branched off on the so-called cold flue gas side of the flue gas stream, especially after this has passed through an air preheater (Luvo) and only a certain / low energy content is available. This results in the temperature shear of a windward from him flowing through, compared to him flowing air larger flue gas mass flow, since the flue gas in addition to the air fuel and water (steam) contains. In this case, the flue gas stream, in particular before it enters a flue gas desulphurisation plant, can then also be deprived of energy via a heat transfer system.

Advantageously, the dried dry lignite (TBK) is supplied as additional fuel at the start of a power plant to the burners instead of, for example, oil or in partial load operation instead of oil or for burner stabilization in bad coals. For this, the dry lignite usually needs 55174

9 be bunkered and be previously cooled for safety reasons. The Trockenbrunkohlenfeuerung is therefore usually an additional firing in addition to the operation of a lignite power plant otherwise taking place Rohbraunkohiefeuerung. D. h., In the vast load range of the power plant is then a Rohbraunkohiefeuerung done and only in the cases of partial load operation, starting the power plant or a necessary burner stabilization, the dried dry lignite is burned.

Since the raw lignite is used as the main fuel in such cases, the resulting flue gas has a very high water content, so it is expedient to first dry the flue gas before it is used for coal drying, as the otherwise given in a wet flue gas, relatively low ΔΤ may not be sufficient for drying coal.

In an embodiment of the method according to the invention, it is advantageous if the drying device and / or drying system is supplied from the flue gas stream branched off from the flue gas line in the flue gas partial stream as tempered flue gas stream.

Particularly expedient, the embodiment of the invention has been found, according to which a portion of the flue gas stream diverted from the flue gas stream in the flue gas flow downstream of a arranged in the strand of the flue gas duct flue gas and arranged in the strand of the flue gas duct flue gas desulphurisation and the drying device and / or drying plant as tempered flue gas flow or tempered flue gas partial stream is supplied.

It is also possible that of the flue gas flow in the flue gas flow direction upstream of a arranged in the strand of the flue gas duct air preheater and / or arranged in the strand of the flue gas duct flue gas desulphurisation a portion of the flue gas stream branched off and the drying device and / or drying system is supplied as tempered flue gas stream or tempered flue gas partial stream.

Furthermore, it has been found to be advantageous if supplied from the flue gas stream 1/3 as tempered flue gas partial stream of the drying device and / or drying system and 2/3 of the flue gas stream in the Rauchgasieitung be continued. The invention therefore further provides that a flue gas substream comprising 30-35% by volume of the flue gas stream is branched off from the flue gas stream and fed to the drying apparatus and / or drying plant as tempered flue gas stream or flue gas substream.

Since downstream of a Luftvorwärmers lower flue gas temperatures than upstream of this air preheater, the drying device and / or the drying system from the location of the branch of the guided in the flue gas line flue gas flow differently tempered flue gas streams are fed. The invention is therefore further characterized in that the drying device and / or drying plant a tempered flue gas stream having a temperature between 110 ° C and 500 ° C, in particular between 120 ° C and 400 ° C, preferably between 180 ° C and 350 ° C. is supplied.

According to a first aspect, the invention is thus characterized by the fact that in a fuel drying flue gas is used as tempered gas stream for the drying of the wet, carbonaceous and particulate fuel, which in particular by the increase in the price of this fuel, in particular after its drying in the drying plant or with the drying method according to the invention, or even in its moist state in the burners of a furnace, in particular the combustion chamber of a steam generator of a lignite power plant, has been generated. There is no hot flue gas, but only a tempered flue gas stream used for the drying, which is fed to the drying device and / or drying system. The use of a flue gas stream and in particular the utilization of its heat content, in particular after this already some flue gas treatment processes or steps, 15 055174

11, for example, a dedusting and desulfurization, subjected and has already been cooled, allows the energetically efficient and cost-effective integration of such a drying plant in an existing power plant, especially lignite power plant. It is also possible to inexpensively integrate the fuel drying process according to the invention and the fuel drying plant according to the invention by retrofitting into existing power plants. The advantage here is that with a technically acceptable effort, in particular control effort, otherwise due to the discharge of the flue gas through a fireplace lost heat energy can be used effectively efficient and not on the expensive and energy-intensive steam produced for the drying of the fuel must be used , Also, the flue gas side flue gas of combustion plants and thus according to the invention to be used tempered flue gas flow to such a low oxygen content that the drying of particulate carbonaceous fuel can be done safely and thus no risk of explosion is justified. Finally, the fuel drying method according to the invention can be carried out in a fuel drying plant, which is technically less complicated and of simple design, since no costly measures to ensure an oxygen content in the flue gas stream or to maintain a certain steam temperature or a certain vapor pressure are necessary.

Since no high temperatures in the drying gas stream are required in the fuel drying process according to the invention, which is decoupled from a mill-drying, it may be sufficient for the drying plant to have a tempered flue gas stream having a temperature of less than 250 ° C., in particular less than 200 ° C., preferably at a temperature between 120 ° C and 150 ° C, is supplied. Characterized in that a flue gas stream is used for fuel drying, on the one hand without further measures has only low oxygen content and on the other hand, when entering the drying device and / or drying plant, especially in a temperature range of below 350 ° C, preferably below 250 ° C, tempered is, this one can Flue gas flow for both a direct, that is direct, as well as for an indirect, that is indirect, heat transfer to be used to be dried wet fuel. It is possible for the moist fuel in the drying plant to be dried directly in direct contact with the tempered flue gas stream, in particular convectively, and / or indirectly by means of a heat flow induced by the tempered flue gas stream.

The drying plant may be the only one associated with a furnace drying plant, but also an additional drying plant. Thus, a power plant, in particular lignite power plant, for example, equipped with such a drying plant dry lignite furnace exclusively or in combination with a lignite coal firing, in particular in the form of a so-called hybrid power plant have. In addition, this can be provided with the combination of direct firing, in which burners are supplied directly from a mill-drying plant or drying plant with fuel, and an indirect firing, in which burners are supplied with fuel from a storage or storage tank or a silo with fuel. It is also possible to provide several burners, possibly fired according to different methods, or burners equipped with different furnaces, for example an RBK or a TBK furnace. It is therefore possible that the drying plant of the power plant burners, in particular by increasing the cost of dried fuel, generated flue gas flow is wholly or partly. In this case, it is also possible for the drying plant to be supplied with at least a partial stream of the flue gas stream formed by combustion of the fuel dried in the drying plant in the burners, in particular power station burners.

In order to achieve a good utilization of the heat energy contained in the flue gas stream, the invention provides in an embodiment several measures.

One measure is that from the flue gas stream at least a portion of the heat energy, in particular by means of a first heat displacement system, coupled and at least partially coupled into the or one of the drying device and / or drying system supplied part of the flue gas stream 5 055174

13 becomes. Another measure is that branched off from the flue gas flow in the flue gas flow direction before entering a / the air preheater part of the flue gas stream, at least part of the heat energy of this further flue gas partial stream, in particular by means of a second heat transfer system, coupled and at least partially into one or the Discharged drying device and / or drying system supplied flue gas sub-stream and this further flue gas stream is fed back to the flue gas stream before the drying device and / or drying plant supplied flue gas partial stream is diverted from the flue gas stream. In this embodiment, therefore, two flue gas partial flows are diverted at different points of the Rauchgasieitung flowing through the flue gas stream of this and thermally interconnected with each other. The dried fuel can be burned in the burners of the combustion chamber or the steam generator of the power plant, in particular lignite power plant, in which case the drying plant of the flue gas stream produced by the burners can be wholly or partly fed. It is therefore also possible for the drying plant to be supplied with at least one partial stream of the flue gas stream which is produced or produced in the burners by combustion of the fuel dried in the drying plant.

The invention is therefore characterized in another embodiment also by the fact that the drying device and / or drying system supplied at least a partial flow in the burners of the combustion chamber or the steam generator total or per unit time to be fired amount of fuel in wet, carbonaceous and particulate fuel and these in the Drying device and / or drying plant by means of one / of the burners by increasing the cost of this, in particular dried, fuel produced and the drying device and / or drying system supplied, tempered flue gas stream is at least partially dried.

In this case, according to a further embodiment of the invention, it is advantageous if by means of the tempered flue gas flow in the drying device and / or Drying plant is a part of the burners of the combustion chamber or the steam generator to be supplied in total or per unit time to be supplied fuel is dried or the fuel to be supplied to the burners of the combustion chamber or the steam generator as a whole or per unit time.

Particularly expedient is the equipment of a lignite power plant or a combustion plant with the inventive method then, when in addition to the dried fuel, other fuel, for example, in addition to the dry lignite and lignite coal and / or biomass is fired. In this case, a particularly advantageous embodiment of the method according to the invention is that by means of the tempered flue gas stream in the drying device and / or drying plant, a partial flow of the fuel quantity is dried, which is up to 70 wt .-%, at least more than 25 wt .-%, preferably more than 17.5% by weight, more preferably more than 10% by weight, which corresponds to the burners of the combustion chamber or of the steam generator currently or, in particular in full-load operation, in total or per unit of time for increasing the amount of fuel supplied.

It is particularly expedient if the moist fuel by means of the tempered flue gas stream in the drying plant to a water content of less than 25 wt .-%, preferably less than 15 wt .-%, dried, what the invention also provides in development. The reduction to such a water or moisture content can be adjusted well with the usually in a lignite power plant, especially with respect to the flue gas, prevailing temperatures and energy and mass flows in the use of conventional lignite coal as fuel to be dried in an energy efficient manner. It is thus possible for the drying plant to be supplied with moist brown coal or biomass or a moist fuel mixture containing brown coal and / or biomass as fuel to be dried.

A particularly advantageous embodiment of the method according to the invention further lies in the fact that the temperature-controlled flue gas flow from a flue gas line with a, the burner having combustion chamber of a steam generator or power plant boiler, preferably a lignite power plant, in Line connection is, in the flue gas flow direction after a plurality of flue gas flow through the flue gas treatment Ana downstream of a stream of the flue gas flow through the air preheater and one of the

Flue gas flow through the flue gas desulphurisation system is diverted and fed to the drying plant. As a result, the fuel drying process according to the invention can be well integrated into existing power plants and their heat and energy flows. A particularly expedient and advantageous measure here is that the flue gas stream is cooled and dried in the flue gas desulfurization system.

But it is also quite possible that alternatively or additionally the tempered flue gas flow from a flue gas line, which is connected to a, the burner having combustion chamber of a steam generator or power plant boiler, preferably a lignite power plant in line connection, in the flue gas flow direction upstream of several flue gas flow through flue gas treatment plants upstream of a branched off from the flue gas flow through the air preheater and a flue gas desulfurization system through which flows the flue gas stream and is fed to the drying plant. In a lignite-fired power plant, the fuel-drying process can be implemented in particular advantageously by virtue of the partial flow of fuel, in particular lignite fuel, to a moisture content of 7-20% by weight, in particular by means of the flue-gas stream originating from the lignite-fired power plant in the drying device and / or drying plant 10 to 18% by weight, particularly preferably 14 to 16% by weight, of which more than 25% by weight, preferably more than 17.5% by weight, particularly preferably more than 10% by weight, is dried. which corresponds to the burners of the combustion chamber or the steam generator currently or, in particular at full load operation, total or per unit time for increased fuel quantity supplied, in particular amount of lignite fuel, or that by means of a

Lignite-fired power plant originating flue gas stream in the drying device and / or drying plant a fuel quantity, especially lignite fuel amount, in its moisture content by drying by 5 - 20 wt -%, especially 8 - 12 wt -.%, Preferably 9 - 11 wt .-% lowered is that of the burners of the combustion chamber or the steam generator currently or, in particular in VoIIiastbetrieb, total or per unit time for increased cost of fuel, in particular lignite fuel quantity corresponds.

In order to set or influence the temperature desired in the tempered flue gas stream, the invention further provides that the branched from the flue gas stream from the flue gas duct, tempered flue gas flow in the flue gas flow upstream of its confluence with the drying device and / or drying plant and in particular in the flue gas flow downstream /of the

Flue gas desulfurization a flue gas cooler, in particular flows through a designed as a direct heat exchanger, preferably as a spray scrubber, flue gas cooler and is cooled and dried here. This may be a NaOH scrubber, which may also be cooled. The cooling water of the flue gas cooler can be used advantageously as additional cooling water in cooling towers, so that it may be appropriate that the cooling water is supplied to the combustion chamber or a steam generator of the industrial plant or power plant, especially lignite power plant, associated cooling tower as cooling tower additive water after flowing through the flue gas cooler.

Also, via a gas-gas heat exchanger, the tempered flue gas stream can be integrated in an energy-efficient manner in the energy balance, that is, the energy and heat flows of a power plant, advantageous. In this regard, the invention provides that the tempered flue gas flow with respect to its flow direction upstream of its confluence with the drying device and / or drying plant a Dampfbeaufschlagbaren heat exchanger with deducted from a steam turbine of a turbo set tapping steam and / or solar-generated steam and / or in a Fresnelsystem generated steam is acted upon, flows through and tempered here.

However, it is also possible to use the combustion system supplied to the furnace, in particular the burners of a combustion chamber of a steam generator, 15 055174

17 to set the desired temperature and in particular a desired oxygen content in the tempered flue gas stream. Here, the combustion air can be diverted in the flow direction in front of a conventional manner present in a power plant existing air preheater or behind the air preheater and the tempered flue gas stream. The invention is therefore also characterized in that the tempered flue gas stream or Rauchgasteiistrom with respect to its flow direction upstream of its confluence with the drying device and / or drying plant and in particular downstream of a flue gas desulfurization, air, in particular after flowing through the / of the air preheater, the in the counterflow of the exhaust-gas side flue gas flow of the combustion chamber or the steam generator or the furnace is flowed through, heated air is admixed. In this case, but also in other process variants, the air can be mixed in such a way that a tempered flue gas stream with an oxygen content of 1 - 15 vol .-%, in particular 1-12 vol .-%, is set. In this case, moreover, a temperature between 1 10 ° C and 250 ° C, in particular between 120 ° C and 200 ° C, can be set.

The inventive method is characterized in refinement and development further characterized by the fact that the air is mixed in such a way that in the tempered flue gas stream or Rauchgasteiistrom an oxygen content of 1 - 15 vol .-%, in particular 1-12 vol .-% adjusted is and / or that in particular in a method according to claim 19, in the tempered flue gas stream or Rauchgasteiistrom a temperature between 110 ° C and 400 ° C, in particular between 120 ° C and 350 ° C, preferably between 120 ° C and 200 ° C, is set. In terms of equipment, the drying device and / or drying system can advantageously be designed and configured as drum dryers, tube dryers, fluidized bed dryers or fluidized bed dryers, as fixed bed dryers or as a mill or combinations of these drying devices in which the fuel is dried. In this case, the fuel can be dried both directly and indirectly in such a system. It is therefore also possible that the fuel in the respective drying device and / or drying plant is dried by direct contact with the tempered flue gas stream, in particular convective, and / or indirectly by contact with heating elements through which the tempered flue gas stream flows.

Since the flue gas stream leaving the drying device and / or drying plant, ie the tempered flue gas stream cooled in the drying device and / or drying plant, carries fuel particles with direct drying of the fuel, it is expedient to provide a filter in the flue gas flow direction behind the drying plant which such fuel particles can be filtered out of the remaining flue gas stream and optionally also supplied to the storage container or silo. It is therefore further advantageous if the tempered flue gas stream with respect to its flow direction downstream of the drying plant of a dedusting in a filter, in particular an electrostatic precipitator or a fabric filter, is supplied.

In order to be able to realize in particular so-called indirect firing in lignite power plants, provision may be made for the dried fuel to be stored in a reservoir, in particular a silo, in relation to its flow direction downstream of the drying device and / or drying plant before it increases its cost.

Since the combustion plant producing the flue gas stream for drying the fuel need not be identical to the furnace in which the fuel dried in the drying plant is burned, it can also be provided that a partial flow of the dried fuel is burned continuously or secondarily in a firing plant which is formed separately from and / or different from the one of the drying device and / or drying plant supplied flue gas stream generating furnace system, 13 and / or together with moist, undried fuel, in particular raw lignite, is burned,

The fuel drying plant according to the invention is characterized in an embodiment in that the drying device and / or drying system a Rauchgasteüstromzuführungsleitung, which is connected in line with a formed on the exhaust side of the combustion chamber or the steam generator and / or the furnace and / or their respective burners flue gas line has, by means of which of the drying device and / or drying plant a branched off from the flue gas line, tempered flue gas partial stream can be fed.

The flue gas partial flow supply line can alternatively, but also in combination, branch off in the flow direction both in front of a flue gas desulfurization system and in front of an air preheater from the flue gas line as well as after this

Flue gas treatment devices or flue gas treatment plants. The invention therefore provides in a further development of the fuel drying system on the one hand, that the flue gas Teilstromzuführungsleitung branches off in relation to the flow direction of the flue gas flowing in the flue gas duct downstream of a arranged in the strand of the flue gas line Luftvorwärmers and / or arranged in the strand of the flue gas line flue gas desulfurization of the flue gas line, and / or that the flue gas partial flow supply line branches off from the flue gas line upstream of a flue gas line arranged in the strand of the flue gas line Luftvorwärmers and / or disposed in the strand of the flue gas line flue gas from the flue gas line with respect to the flow direction of the flue gas flowing in the flue gas line.

To be able to reheat the branched tempered flue gas partial stream, if desired, the invention also provides that in the flue gas partial flow supply line a particular steam-susceptible heat exchanger is arranged, with the drawn off from a steam turbine of a turbine set of the power plant bleed steam and / or solar-generated steam and / or acted upon by steam generated in a Fresnelsystem and by means of which guided in the Rauchgasteilstromzuführungsieitung

Flue gas partial stream is temperature controlled.

In order to achieve an advantageous interconnection of heat energy flows, it is further advantageous according to the invention, if in the Rauchgasteiistromzuführungsleitung a first heat transfer system is arranged, which is in operative connection with the flue gas line and by means of which guided in the flue gas partial flow supply line flue gas substream from the in the flue gas line guided flue gas stream coupled heat energy can be supplied.

Alternatively, or in combination with it, it is also possible that in the Rauchgasteiistromzuführungsleitung a second heat transfer system is arranged, which is connected to a branching off of the flue gas line and in particular a disposed therein Luftvorwärmer immediate Rauchgasabzweigungsleitung and by means of which guided in the flue gas Teilstromzuführungsleitung flue gas substream from the in the flue gas branch line guided flue gas flow coupled out heat energy can be supplied.

In order to be able to control its temperature and / or its oxygen content in the tempered flue gas partial stream before it enters the drying device and / or the drying plant, according to a further embodiment of the invention, the flue gas partial flow supply line is connected to at least one of the combustion chamber or the steam generator or the firing system combustion air supplying combustion air supply line branching first and / or second air supply line is in line connection, by means of which / which is guided in the flue gas partial stream supply line tempered flue gas stream air.

For the interconnection of the heat energy flows of the fuel drying plant, it is particularly useful and advantageous, although a shift of 15 055174

21

Heat energy from the guided in the flue gas line flue gas flow to the air flowing in the air supply combustion air is possible. The invention is therefore also characterized in that in the flue gas line, a third heat transfer system is operatively connected to a / the combustion air supply line and by means of which the outgoing in the combustion air supply line combustion air from the guided in the flue gas line flue gas heat energy can be supplied. Finally, the invention provides that the drying plant has a drying device through which the tempered flue gas stream flows or a drying device through which the tempered flue gas stream flows and at least one associated co-pulveriser connected to the drying device or is designed as a coal mill, in particular a beater mill or a beater mill.

The fuel drying plant and in particular the drying device and / or the drying plant and at least the furnace and / or the combustion chamber or the steam generator may be an integral part of an industrial plant or a power plant, in particular a lignite power plant, wherein the drying plant then in the B re nn substance strö mu ng s away and in the flue gas flow path of the industrial plant or the power plant is integrated circuit-wise. This makes it possible to advantageously integrate a fuel drying process according to the invention into a power plant complex or an industrial plant in technical and energy terms.

In order to be able to set or influence the temperature and the oxygen content of the tempered flue gas stream in a targeted manner, the flue gas partial flow supply line can be in line connection with at least one air feed line supplying combustion air to the furnace. It is particularly expedient if the flue gas partial flow supply line with a downstream in the flow direction of the combustion air downstream of a flowing through in countercurrent of hot flue gas of the combustion system Luftvorwärmers second air duct and / or with an in Flow direction of the combustion air upstream of a branched in countercurrent of hot flue gas of the furnace system Luftvorwärmers first air duct is in line connection.

From an energy-technical point of view, the use of a tempered flue gas stream is advantageous, which is branched off in the flue gas flow direction according to a flue gas desulphurisation system usually present in the flue gas line of a power plant. It is therefore possible that the flue gas partial flow supply line with respect to the flow direction of the tempered flue gas flow downstream of a

Flue gas desulphurisation system branches off from the flue gas outlet.

In order to be able to use fuel particles entrained by the tempered flue gas stream flowing through the drying device and / or drying plant, it is expedient for the fuel drying plant to have one of these associated with the flow direction of the tempered flue gas stream downstream of the drying device and / or drying plant line connected filter, in particular an electrostatic filter or a fabric filter having.

Also advantageous is the formation of the drying device and / or drying plant as a drum dryer, tube dryer, fluidized bed plant or fluidized bed dryer, as a fixed bed dryer or as a mill or as a combination of one or more of these drying devices.

The invention is explained in more detail below by way of example with reference to a drawing. This shows in

1 is a schematic representation of a first embodiment of the

Invention with integration of a drying device and / or drying plant comprehensive

Fuel drying plant in the flue gas discharge of a power plant, a schematic representation of a second exemplary embodiment of the invention with the involvement of a drying device and / or drying plant comprehensive

Fuel drying plant in the flue gas discharge of a power plant and in

Fig. 3 - 11 in a schematic representation of a third to eleventh

Ausführungsbeispie! of the invention with involvement of a drying device and / or drying plant comprehensive

Fuel drying plant in the flue gas outlet of a power plant.

Fig. 1 shows a schematic representation of a dashed lines merely indicated combustion chamber 1 of a steam generator of a lignite power plant, in the burners dry fuel or dried fuel 2 is burned as fuel. In the exemplary embodiment, the dried fuel 2 or dry fuel should be dried lignite, so that here a dry lignite (TBR) firing is indicated by the dashed lines , In a manner not shown, the combustion chamber 1 but also other, additional fuel, for example, in parallel or by selecting some of the burners of the combustion chamber 1 are supplied. In particular, for this purpose in a lignite power plant, the supply of raw lignite, which may have previously undergone a Mahltrocknungsprozess conceivable, so that in addition also in a manner not shown a raw lignite (RBK) - firing may be provided in parallel, the two types of firing simultaneously or in parallel can be operated alternately each as a single firing. In this respect, the indicated power plant 16 may be a so-called lignite-hybrid power plant. In order to enable intermediate storage of the dry fuel 2 before its combustion, a silo or storage tank 4 is arranged in the dry fuel supply line or fuel discharge line 3 shown in dashed lines. Also the possibly existing ones RBK-firing may optionally include Vorraisbehälter or silos, especially if this is at least formed in one part as an indirect firing. In a known and customary manner opens into the combustion chamber 1, a combustion air supply line 5, with which the burners of the combustion chamber 1, the required combustion air is supplied. On the exhaust side, the flue gas produced during the combustion of the fuel or a fuel 2, 14 in the burners of the combustion chamber 1 is at least partially, but in particular completely, arranged by means of a flue gas duct 6 in the strand of the flue gas duct 6 flue gas treatment devices, of which in Figs. 1 and 2 only one Air preheater (Luvo) 7, an electrostatic filter 8 and a flue gas desulfurization system 9 dargesteiit are supplied before the flue gas line 6 and thus the treated flue gas or exhaust gas flows into a cooling tower 10, from which the treated flue gas then escapes into the ambient air.

From the flue gas line 6 branches in the flow direction of the flue gas downstream of the flue gas desulfurization system 9 a flue gas partial flow supply line 1 1 from the flue gas line 6, which in a

Drying unit 12 opens and the drying unit 12 to an integral part of the flue gas partial flow supply line 11 making this emerges again and then downstream in the flue gas flow direction their branch of the flue gas line 6 opens again into the flue gas line 6. As a result, a guided in the flue gas partial flow supply line 11 tempered flue gas stream or flue gas partial stream is diverted from the original flue gas stream of the combustion chamber 1 and recycled into this. The drying installation 12 is one without an integrated grinding process, ie, for example, not a beater mill, but a drum dryer or tube dryer through which the tempered flue gas stream flows in the flue gas partial flow supply line 11 or a fluidized bed system through which the tempered flue gas flow passes. But it is also possible to use mills 25a-25c or a grinding plant as Trocknungsaniage 12, as explained below with reference to further embodiments becomes. In the drying plant 12 opens a fuel supply 13, by means of which the drying unit 12 to be dried, moist, carbonaceous and particulate fuel 14, in particular raw lignite, but also biomass, or a fuel mixture containing both types of fuel supplied.

After drying within the drying installation 12, this fuel 14 is supplied as dried fuel 2 to the dry fuel feed line or fuel discharge line 3 branching off from the drying installation 12, by means of which it is supplied to the storage container 4 and / or the combustion chamber 1. In the exemplary embodiment, the drying plant 12 is fed a moist brown coal with a moisture content of 54%, which is dried in the drying plant 12 to a dried fuel 2 or dry fuel, which still has a residual moisture content of 15%. The loop of the flue gas partial flow supply line 11 from its branch from the flue gas line 6 to the re-confluence with the flue gas line 6 forms with the integrated therein drying plant 12, the total designated 15 fuel drying system. Since it is in the exemplary embodiment to the combustion chamber of a steam generator of a lignite power plant with not Pictured, but trained in a conventional manner connected water / steam cycle with integrated turbo set, the fuel drying system 15 and thus the drying unit 12 as an integral part of such power plant 16, in particular lignite power plant, formed and incorporated in the fuel flow path (s) and in the / the fuel flow path (s) and in the / the flue gas flow path (s) of the total designated 16 power plant line. However, this is not necessarily the case and can not be the case in other embodiments of the invention. From the combustion air supply line 5 branches off in the flow direction of the combustion air to the combustion chamber 1 in front of the air preheater 7 and thus upstream of the air preheater 7, a first air supply line 17, in the flow direction of the tempered flue gas stream in the flue gas partial flow supply line 1 before the drying plant 12 and thus in With respect to the flow direction of the temperature-controlled flue gas flow upstream of the drying plant 12 opens into the flue gas partial flow supply line 11. A second air supply line 18 branches off behind the air preheater 7 and thus downstream of the air preheater 7 of the combustion air supply line 5 and opens in a region between the confluence of the first air supply 17 and the drying system 12 in the flue gas partial flow supply line 11, by means of the first and / or second air supply line 17 and 18, cold, heated or warm air can be fed to the tempered flue gas stream flowing in the flue gas partial flow supply line 11. This allows the oxygen content in the tempered flue gas stream before entering the drying plant 12, but also regulate its temperature. In the exemplary embodiment, by means of the first air supply line 17, for example, about 44 ° C or about 114 ° C hot air, depending on whether a heat exchanger 19 is in operation or not, the tempered flue gas stream are supplied. By means of the second air supply line 18, the temperature-controlled flue gas flow can be supplied with a combustion air flow at a temperature of 270 ° C. The higher temperature in the second air supply line 18 results from the fact that the guided in the combustion air supply line 5 combustion air is heated in the air preheater 7 due to the countercurrent flowing through this flue gas stream by heat exchange. With regard to the flow direction of the temperature-controlled flue gas flow behind the drying plant 12 and thus downstream of the drying plant 12, a filter 20 is arranged in the flue gas partial flow supply line 11, which may be an electrostatic precipitator or a fabric filter. By means of this filter 20 are entrained by the tempered flue gas stream when flowing through the drying unit 12 fuel particles from the then cooler

Flue gas stream filtered out and fed as dried fuel 2 also the fuel discharge line 3 or dry fuel supply line.

The flue gas stream branched off from the flue-gas line 6, for example, enters the flue-gas partial-flow supply line 11 at a temperature of approximately 67 ° C. and is heated up to a temperature of approximately 192 ° C. during its course, until it enters the drying plant 12. In the embodiment according to Figures 1 and 2 is in the flow direction of the temperature-controlled flue gas flow upstream of the drying plant 12 and downstream of the branch of the Rauchgasteüstromzuführungsleitung 11 of the flue gas duct 6 in the flue gas partial flow supply line 11 arranged a flowed through by the tempered flue gas flow flue gas cooler 21. When flowing through the

Flue gas cooler 21, the temperature of the tempered flue gas stream of about 87 ° C to about, 40 ° C is reduced. The flue gas cooler 21 may be a direct heat exchanger, for example a spray scrubber, in particular a NaOH scrubber. The used in the flue gas cooler 21 cooling water is supplied to the Kühiturm 10 in a manner not shown as a cooling tower auxiliary water after flowing through the flue gas cooler 21.

In the flue gas partial flow supply line 1 1, a fan 22 is then arranged in the downstream direction of the temperature-controlled flue gas flow, in the flow through the tempered flue gas again a temperature increase, for example, to about 45 ° C experiences.

In addition, further downstream flow direction of the tempered flue gas flow in the flue gas Teilstromzuführungsieitung 1 1, a further heat exchanger 23 is formed. The further heat exchanger 23 may be equipped as well as the heat exchanger 19 with a steam heating. The steam heating of the further heat exchanger 23 and the heat exchanger 19 may be such that the further heat exchanger 23 or the heat exchanger 19 tapping steam from a steam turbine of the turbo set of water / steam cycle of the power plant 16 and / or steam, which has been generated solar, and / or steam, which has been generated in particular with a Fresnelsystem supplied. In the exemplary embodiment, the tempered flue gas stream flowing in the flue gas partial flow supply line 11 is supplied with so much heat energy by means of the further heat exchanger 23 that it is reheated in relation to its flow direction downstream of the further heat exchanger 23 to a temperature of approximately 152 ° C. By means of the heat exchanger 19, it is possible due to the steam heating to heat the supplied combustion air in the combustion air supply line 5 to a temperature of about 114 ° C, at which temperature this combustion air also enters the first air supply line 17. By appropriate adjustment of the supplied through the first and second air duct 17, 18 Amount of air can then downstream of the further heat exchanger 23 set the temperature of the tempered flue gas flow in the flue gas partial flow supply line 11 to the already mentioned about 192 ° C, with which the tempered flue gas stream for drying in the drying plant 12 to the mass flow of wet, carbonaceous and particulate fuel 14 hits. By means of the first and second air supply line 17, 18, the tempered flue gas stream air and thus oxygen is mixed regulated such that in the tempered flue gas flow, an oxygen content of 1-15 vol .-%, in particular 1-12 vol .-% and a temperature between 10 ° C and 250 ° C, in particular between 120 ° C and 200 ° C, is set.

The embodiment of Figure 2 differs from the embodiment of Figure 1 only in that there is still a first heat transfer system 24 is formed in the form of a gas-gas heat exchanger. This first heat transfer system 24 is arranged on the one hand between the electrostatic precipitator 8 and the flue gas desulfurization 9 in the flue gas line 6 and on the other hand between the flue gas cooler 2, but in particular the blower 22, and the other heat exchanger 23 with steam heating in the flue gas partial flow supply line 1 1. This makes it possible to transfer heat energy contained in the flue gas between the electrostatic precipitator 8 and the flue gas desulphurisation plant 9 to the temperature-controlled flue gas flow and to feed this into the flue gas partial flow supply line 11. For example, the temperature-controlled flue gas flow can be heated from a temperature of about 45 ° C, which he has after flowing through the blower 22, to a temperature of about 1 13X, which he then has before flowing through the further heat exchanger 23.

By means of such, in the fuel streams and heat energy flows of a power plant 16 integrated fuel drying system 15, it is possible to efficiently and effectively provide the drying plant 12 from the energy and heat flows and mass flows, in particular the flue gas mass flow of the power plant 16 with energy sufficient to dry supplied wet fuel 14 in a manner sufficient for the subsequent combustion. In particular, it is possible to retrofit the inventive fuel drying system 15 as a retrofitted device or device or system with relatively little technical effort in an existing power plant 16 as a retrofit.

By means of such a fuel drying plant 15, it is possible to carry out a fuel drying process in which the drying plant 12 at least a partial flow of moist, carbonaceous and particulate, to be dried fuel 14 is supplied, which is a part of the burners in particular the combustion chamber 1 total fuel quantity to be fired equivalent. This part Ström to be dried fuel 14 is at least partially dried in the drying plant 12 by means of a particularly in burners of the combustion chamber 1, but possibly also in other burners of a furnace of the power plant 16 and the drying plant 12 fed tempered flue gas stream at least. In this case, the flue gas stream used for the drying can also be produced by at least a portion of the dried fuel 2 produced in the drying plant 12 being burned or fired in the combustion chamber 1 or a firing plant. In order to dry the moist fuel 14 sufficiently, ie to be able to reduce its moisture content, the tempered flue gas stream of the drying plant 12 is preferably at a temperature of less than 250 ° C, in particular less than 200 ° C, particularly preferably with a temperature between 120 ° C and 150 ° C, fed. In this case, the drying plant 12 in the exemplary embodiment is one in which the moist and particulate fuel 14 to be dried is in direct contact with the tempered flue gas stream, so that convective drying is carried out here. Furthermore, in this case it is possible for the entire fuel to be supplied to the combustion chamber 1 with respect to a time unit or a mass flow to be partially dried as dried fuel 2 or dry fuel, which has not yet reached its final content in relation to its residual moisture , But it is also possible to produce here only a portion of the combustion chamber 1 as a whole or per unit time or in relation to a mass flow to be supplied dried fuel 2, but for the desired Endfeuchtigkeitsgehalt already has. Overall, the Trocknungsaniage is designed so that it is a partial flow of

Can be supplied to the amount of fuel for drying, which corresponds to more than 25 wt .-% and up to 70 wt .-% of the current or per unit time the burners of the furnace especially the burners of the combustion chamber 1 in total to increase the amount of fuel supplied. The moisture content resulting from drying to the final moisture content is less than 25% by weight, preferably less than 15% by weight, in the dried fuel 2 leaving the drying plant.

Since the exemplary embodiments according to FIGS. 1 and 2 differ only in relation to the first heat displacement system 24 in the form of a gas-gas heat exchanger, the same reference symbols are used in both embodiments and denote identical objects in each case.

Similarly, in the following embodiments of the invention according to Figures 3 to 1 1 identical reference numerals designate identical or equivalent elements or system parts. Also in these embodiments, a tempered flue gas stream or flue gas partial stream of a drying device and / or drying system 12 is supplied. Depending on the thermal insulation shadow cold, dried and then reheated flue gas is used, which is preferably branched off at the end of a flue gas treatment line after flowing through a desulfurization 9 of the flue gas line 6. Or it is warm flue gas, preferably after flowing through the throttle cable of a power plant boiler before

Admission is branched off in an air preheater 7 arranged in the strand of the flue gas line 6, the drying device and / or drying system 12 is supplied. Further interconnection options represent targeted admixtures of air, in particular the combustion air, or heat couplings in the tempered flue gas (part) stream.

FIG. 3 discloses an exemplary embodiment which differs essentially from the embodiment according to FIG. 1 in that the fuel drying system 15 comprises a drying system 12, which comprises two _{3 χ}

Coal mills 25a, 25b are assigned. The fuel 14 to be dried is first supplied to the first coal mill 25 a and then comminuted into the drying plant 12. There, the fuel 14 is dried and supplied as dried fuel 2 of the coal mill 25 b and ground to the final size. The dried fuel 2 leaving the grinding plant 25b is then fed to the storage tank or silo 4 (not shown) and / or the burners of the combustion chamber 1. Another difference is that in the flue gas flow direction of the flue gas line 6 before the confluence with the air preheater 7 branches off a flue gas branch 26, which opens in the flue gas flow direction downstream of the air preheater 7 back into the flue gas line 6. In the region of the flue gas branch pipe 26, a second heat displacement system 27 is arranged, which is flowed through in countercurrent of the tempered flue gas stream, which can be heated in this way before entering the drying plant 12 again. The flue gas branched into the flue-gas branch line 26 has a temperature which is in the range of 300 to 500 ° C.

The embodiment of FIG. 4 differs from that of FIG. 3 only in that here the drying unit 12 consists of only one coal mill 25 c, in which as fuel 14 raw lignite dried by supplying the tempered flue gas stream and then together with the flue gas stream the Filter 20 is supplied, where then flue gas and dried fuel 2 are separated from each other. In this case, the coal mill 25c may also be designed as a beater wheel mill, so that here the drying plant 12 comprises an integrated grinding process.

In an analogous manner, the embodiment according to FIG. 5 differs from that according to FIG. 3 and the embodiment according to FIG. 6 differs from that according to FIG. 4 in that here, on the one hand, a first heat displacement system analogous to the embodiment according to FIG 24 between the flue gas duct 6 and the

Flue gas partial flow supply line 1 1 is formed and that in the

Combustion air supply line 5, a heat exchanger 19 is arranged. Also opens here a second air supply line 18 in the

Flue gas partial flow supply line 1 1, which in the flow direction of ^

Combustion air branches off downstream of the air preheater 7 of the combustion air supply line 5. In addition, in the flue gas Teilstromzuführungslertung 1 1 in an analogous manner to the

Embodiments according to Figures 1 and 2, a further heat exchanger 23 downstream of the first heat displacement system 24 is arranged and formed.

The embodiments according to Figures 7 and 8 correspond substantially to those of Figures 3 and 4. In contrast to these embodiments, in the combustion air supply line 5 in the flow direction of the combustion air upstream of the air preheater 7, a third heat transfer system 28 is arranged in the Rauchgasieitung 6 at a Point downstream of the electrostatic precipitator 8 and upstream of the flue gas Entschwefeiungsanlage 9 in heat energy from the flue gas flow einkoppelnder manner with the flue gas flow of the combustion chamber 1 is in operative connection. As a result, the combustion air can be heated.

In the embodiments according to FIGS. 3 and 4 as well as 7 and 8, approximately one third of the flue gas flowing in the flue-gas line 6 is branched off via the flue-gas branch line 26 and fed to the second heat-displacing system 27.

Likewise, it has proven to be useful in all embodiments according to FIGS. 1 to 8 and Fig. 9 to 1 1 of the flue gas line 6 each about one third of the flowing flue gas in the flue gas Teilstromzuführungslertung 1 1, 11 'or 1 1 "branch off and leaving two-thirds of the flue gas in the flue gas duct 6 (and supplying it to the cooling tower 10).

In the embodiments according to FIGS. 3, 5 and 7, the drying installation 12 respectively consists of a drum dryer, through which the tempered flue gas stream is guided and a first coal mill 25a and a downstream second coal mill 25b connected upstream therefrom. In the embodiments according to FIGS. 4, 6 and 8, the drying plant 12 is designed in each case as a beater mill 25c and thus as a grinding drying plant. FIG. 9 shows an embodiment in which a flue gas branch line 26 'branches off from the flue gas line 6 as flue gas partial flow feed line 11' and opens into the drying plant 12, so that a flue gas sub-stream as tempered flue gas stream flows through the lines 1 1 ', 26' in this way Drying system is supplied. Since the flue gas partial flow supply line 11 'branches off from the flue gas line 6 in the flow direction of the flue gas upstream of the air preheater 7, it is provided for enabling a temperature control that the second air supply line 18' branching off in the direction of flow of the combustion air downstream of the air preheater 7 from the combustion air supply line 5 into the flue gas partial flow supply line 1 1 'opens before the confluence in the drying plant 12. As a result, the temperature-controlled flue gas partial flow through the second air supply line 18 'supplied tempered air can be mixed.

In a power plant according to FIG. 12, no flue gas partial flow is now branched off from the flue gas flow generated in the combustion chamber 1 and passed through the flue gas duct 6, but the drying plant 12 is arranged in the flue gas duct 6, so that it is flowed through by the entire flue gas flow and its Heat energy for the drying of the wet fuel 14 is available. In order to allow dust deposits before the entry of the flue gas stream into the drying plant, the drying plant 12 in this embodiment, upstream of a cyclone 29 in the flow direction of the flue gas. Between the electrostatic precipitator 8 and the flue gas desulphurisation plant 9, in this embodiment, in turn, a third heat displacement system 28 is formed, by means of which thermal energy is decoupled from the flue gas flow into the air flow supplied to the combustion chamber 1. Embodiments of the present invention in which dust 30 is removed from the tempered flue gas stream by means of a cyclone 29 are shown by the embodiments according to FIGS. 10 and 1. In these embodiments, the temperature-controlled flue gas flow is again in the flow direction of the flue gas upstream of the air preheater 7 by means of a Flue gas branch line 26 "branched off and in a flue gas partial flow supply line 11" first the cyclone 29, then designed as a beater mill coal mill 25c. the Trocknungsaniage 12 is formed, and then fed to a filter 20 before the Rauchgasteifstromzuführungsieitung 1 1 "or flue gas branch line 26" opens again into the flue gas line 6. This is done in the flow direction of the flue gas in the flue gas line 6 downstream of the electrostatic precipitator 8 and upstream of the flue gas desulfurization 9. In the coal mill 25c moist fuel 14 is again entered and dried convectively by means of the supplied tempered flue gas stream. The separation of flue gas stream and dried fuel takes place in the filter 20.

The embodiment of FIG. 1 1 differs from that of FIG. 10 only in that here in the flue gas line 6 between the electrostatic filter 8 and the flue gas desulfurization 9 and in the flow direction of the flue gas upstream of the confluence of the flue gas branch line 26 "in the flue gas line. 6 in turn, a third heat displacement system 28 is formed, heat energy is coupled out of the flue gas flow in the flue gas duct 6 and coupled into the air flow guided in the combustion air supply duct 5. Also in the embodiments according to FIGS. 10 and 11, by means of the flue gas branch conduit 26 ". in turn about one third of the guided in the flue gas duct 6 flue gas branched off and the drying plant 12.

In particular, in the embodiments in which the tempered flue gas stream is diverted from the flue gas stream of the combustion chamber 1, before the total flue gas has flowed through the desulfurization 9, in the temperature control in the flue gas partial flow supply lines 11 'and 11 ", the temperature control is designed so that at least until after Exit from the respective drying plant 12 and / or the respective filter 20, the upper acid dew point is not reached, so the temperature is 120 ° C. Preferably, this condition is also maintained until the confluence of the flue gas partial flow supply lines 11 'and 11 "in the flue gas line 6. Overall, three basic types of methods are described above. The first type of process relates to the diversion of a temperature-controlled flue gas flow from the flue gas stream leaving the combustion chamber 1 and in particular also its gas flue, after the flue gas flow has passed through a flue gas treatment section arranged and formed in the flue line and leaving a flue gas desulphurisation plant 9 at its end. The reconnection of the flue gas partial flow supply line 11 takes place in the flow direction of the flue gas flow behind or downstream of the flue gas desulfurization system 9. This type of process is shown in FIGS. 1, 2, 5 and 6.

FIGS. 9 to 11 show another type of process. In this type of process, the branching of the tempered flue gas stream fed to the drying plant 12 takes place from the flue gas stream before it enters the flue-gas treatment line, and in particular before it flows into the air preheater 7. The recirculation of the branched Rauchgasteiistromes takes place in the area of the flue gas treatment line and in particular in the flue gas flow direction before and upstream of the flue gas desulfurization 9, wherein according to the embodiment of FIG. 9, the reunion of the Rauchgasteiistromes in the flow direction in front of the electrostatic filter 8.

The further Figures 3 and 4 and 7 and 8 disclose combinations of these two types of processes, wherein the respectively branched Rauchgasteiistrom is returned to the original flue gas stream before a second diversion of a Rauchgasteiistromes takes place.

FIG. 12 shows a fourth type of process in which no flue gas stream is branched off, but the entire flue gas stream generated in the combustion chamber 1 is fed to the drying plant 12.

The above-described flue gas treatment section extends in the embodiments of the air preheater 7 to the desulfurization 9. A subsequent possibly subsequent C02 deposition is not part of the Flue gas treatment section. The tempered flue gas (part) stream is branched off before a C02 deposition device or plants.

In a manner not shown can be arranged in the embodiment of FIG. 9 in the flow direction of the tempered flue gas partial stream behind the drying unit 12 in the flue gas partial flow supply line 11 'also a filter, in particular an electrostatic filter, are filtered out with which still remaining in the flue gas flow dried fuel 2 can. In this case, it is then also advantageous if the flue gas partial flow supply line 11 "and the flue gas branch line 26" open in the flue gas flow direction behind and thus downstream of the electrostatic precipitator 8 back into the flue gas line 6. In this embodiment, the supply of warm combustion air by means of the second air supply line 18 'is used to lower the water content in the branched off from the flue gas line 6 and in the flue gas branch line 26' guided flue gas substream. In this respect, the water content in the flue gas partial flow and not the temperature of the flue gas substream is regulated in this embodiment.

Depending on the embodiment, the heating-technical shadows are such that, after flowing through the flue-gas treatment section, cold, dried flue gas is branched off and then reheated before it is fed to the respective drying system 12, and / or hot or warm flue gas from the flue-gas stream before entering the flue-gas treatment section branched off and then either the drying plant 12 or heat exchanger devices. for example, the second heat displacement system 27, is supplied.

Before the dried fuel 2 is burned in the burners of the combustion chamber 1, it is usually stored in the reservoir or silo. The residence time in the storage container 4 can be between 15 minutes and several days.

In principle, 12 cold air and / or hot air can be added to the branched in the flow direction of the flue gas before entering the air preheater 7 flue gas partial stream before it enters the respective drying plant, wherein only the maximum permissible oxygen content in the flue gas partial flow / air mixture must be maintained. The heating of the flue gas substream can be done at various points, for example by means of a heat exchanger 23 and also by means of in particular from the water / steam cycle of the connected power plant 16 tapped steam.

Component of the drying equipment 12, the most diverse

Drying units such as mills 25a to 25c, coal mills,

Blower mills, beater mills, drum dryers, tube dryers, fluidized bed dryers or fixed bed dryers.

At the time of diversion of a tempered flue gas (part) stream from the flue gas stream flowing in the flue gas line 6, this has a temperature of well below 1000 ° C and a maximum of about 500 ° C.

Claims

claims

Anspruch [en] A process for drying damp, carbonaceous and particulate fuel (14) to be burned in burners of a combustion chamber (1) or a steam generator of a power plant, preferably lignite power plant, in particular a dry lignite power plant, and / or a firing plant in a drying device and / or drying plant (12 ) of the power plant (16), wherein the drying device and / or drying system (12) fed a tempered gas stream and the fuel (14) in the drying device and / or drying system (12) by means of the tempered gas stream and / or decoupled from this heat energy dried and the dried fuel (2) is supplied to a storage container (4) and / or burners of the combustion chamber (1) or the steam generator of the power plant (16) and / or the furnace

in which

in the combustion chamber (1) or the steam generator and / or the, in particular separate, combustion plant by combustion of fuel (2, 14) generates a flue gas stream and this downstream in the flue gas flow direction downstream and outside the combustion chamber (1) or the steam generator or the furnace in a flue gas line (6) is transferred, and at least a portion of the flue gas stream as tempered flue gas stream in one of the flue gas line (6) branching off Rauchgasteiistromzuführungsleitung (11, 11 ', 1 ") diverted and in the strand of the flue gas partial power supply line (1 1, 11, 11 ") arranged drying device and / or drying plant (12) is supplied, characterized

the thermal energy of the tempered flue gas stream in the drying device and / or drying plant (12) is at least partially transferred to the fuel (14) to be dried and the temperature-controlled flue gas flow via the flue gas partial flow supply line (11, 11 ', which opens into the flue gas line (6) again). 1 1 ") is returned to the flue gas stream. A method according to claim 1, characterized in that the

Drying device and / or drying system (12) one of the in the flue gas line (6) guided flue gas flow branched off flue gas partial stream is supplied as tempered flue gas stream.

A method according to claim 1 or 2, characterized in that of the flue gas flow in the flue gas flow direction downstream of a strand of the flue gas line (6) arranged Luftvorwärmers (7) and / or arranged in the strand of the flue gas line (6)

Flue gas desulfurization (9) branched off a portion of the flue gas stream and the drying device and / or drying system (12) is supplied as tempered flue gas stream or tempered flue gas partial stream.

Method according to one of claims 1 - 3, characterized in that of the flue gas flow in the flue gas flow direction upstream of a strand of the flue gas line (6) arranged Luftvorwärmers (7) and / or in the strand of the flue gas line (6) arranged flue gas desulfurization (9) a part branched off the flue gas stream and the drying device and / or drying system (12) is supplied as tempered flue gas stream or tempered flue gas partial stream.

Method according to one of the preceding claims, characterized in that branched off from the flue gas flow 30- 35 vol .-% of the flue gas stream comprehensive flue gas partial stream and as tempered flue gas stream or flue gas partial stream of the drying device and / or drying plant (12) is supplied.

Method according to one of the preceding claims, characterized in that the drying device and / or drying system (12) a tempered flue gas stream having a temperature between 1 10 ° C and 500 ° C, in particular between 120 ° C and 400 ° C, preferably between 180 ° C and 350 ° C, is supplied. Method according to one of the preceding claims, characterized in that from the flue gas stream at least a part of the heat energy, in particular by means of a first Wärmeverschubsystems

(24), decoupled and at least partially in the or one of the drying device and / or Trocknungsaniage (12) supplied part of the flue gas stream is coupled.

Method according to one of the preceding claims, characterized in that diverted from the flue gas flow in the flue gas flow direction before entering a / the air preheater (7) part of the flue gas stream, at least a portion of the heat energy of this werteren flue gas substream, in particular by means of a second Wärmeverschubsystems (27) , decoupled and at least partially in one or the drying device and / or drying system (2) supplied Rauchgasteiistrom coupled and this further flue gas stream is fed back to the flue gas stream before the drying device and / or drying system (12) supplied Rauchgasteiistrom is diverted from the flue gas stream.

Method according to one of the preceding claims, characterized in that the drying device and / or drying system (12) at least a partial flow of fuel in the burners of the combustion chamber (1) or the steam generator total or per unit time to be fired amount of moist, carbonaceous and particulate fuel ( 14) and these in the Trocknungsvorrächtung and / or drying plant (12) by means of one / by the burners by burning this, in particular dried fuel (2, 14) generated and the drying device and / or drying system (12) supplied tempered flue gas stream at least partially dried.

Method according to one of the preceding claims, characterized in that by means of the tempered flue gas stream in the drying device and / or drying plant (12) a part of the Burners the combustion chamber (1) or the steam generator is dried in total or per unit time to be supplied fuel or the burners of the combustion chamber (1) or the steam generator is supplied in total or per unit time to be supplied fuel is partially dried.

11. The method according to any one of the preceding claims, characterized in that by means of the tempered flue gas stream in the drying device and / or drying plant (12) a partial flow of the fuel quantity is dried, the up to 70 wt .-%, at least more than 25 wt. %, preferably more than 17.5% by weight, particularly preferably more than 10% by weight, which corresponds to the burners of the combustion chamber (1) or of the steam generator currently or, in particular at full load operation, total or per unit time for increased fuel quantity supplied ,

12. The method according to any one of the preceding claims, characterized in that the moist fuel (14) by means of the tempered flue gas stream in the drying apparatus and / or drying plant (12) to a water content of less than 25 wt .-%, preferably less than 15 wt .-%, is dried.

13. The method according to any one of the preceding claims, characterized in that the tempered flue gas flow from a flue gas line (6), which is connected to a, the burner having combustion chamber (1) of a steam generator or power plant boiler, preferably a lignite power plant, in line connection, in the flue gas flow direction a plurality of flue gas treatment systems through which the flue gas stream flows downstream of a flue gas desulphurisation system (7) through which the flue gas flow passes and a flue gas desulphurisation system (9) through which the flue gas flows and to the drying installation (12).

14. The method according to any one of the preceding claims, characterized in that the tempered flue gas flow from a flue gas line (6), with a, the burner, having combustion chamber (1) a steam generator or power plant boiler, preferably a lignite power plant, is in line connection, branched off in the flue gas flow direction upstream of a plurality of flue gas flow through flue gas treatment plants upstream of a flue gas flow through the air preheater (7) and a flue gas flow through flue gas desulfurization (9) and the Trocknungsaniage (12 ) is supplied.

15. The method according to any one of the preceding claims, characterized in that by means of a raf twe rk from a lignite tarmank originating flue gas stream in the drying device and / or drying plant (12) a partial flow of the fuel quantity, in particular lignite fuel quantity, to a moisture content of 7-20 wt. %, in particular 10 to 18 wt.%, particularly preferably 14 to 16 wt.%, of which more than 25 wt.%, preferably more than 17.5 wt.%, particularly preferably 10 wt. -%, which corresponds to the burners of the combustion chamber (1) or the steam generator of the lignite power station currently or, in particular at full load, total or per unit time to increase the amount of fuel supplied, in particular lignite fuel quantity.

16. The method according to any one of the preceding claims, characterized in that by means of the derived from a lignite power plant flue gas stream in the drying device and / or drying plant (12) a fuel quantity, especially lignite fuel quantity, in its moisture content by drying by 5 - 20 wt, -%, in particular 8-12% by weight, preferably 9-1.1% by weight, of the burners of the combustion chamber (1) or of the steam generator of the lignite power plant or, in particular at full load operation, in total or per unit time for increased cost Fuel quantity, especially lignite fuel quantity corresponds.

17. The method according to any one of the preceding claims, characterized in that the of the flue gas stream from the flue gas line (6) branched off, tempered flue gas flow in the flue gas flow direction upstream of its confluence with the drying apparatus and / or

Drying plant (12) and in particular in the flue gas flow downstream of a flue gas desulfurization (9) a

Flue gas cooler (21), in particular flows through a designed as a direct heat exchanger, preferably as a spray washer, flue gas cooler (21) and is cooled and dried here.

18. The method according to any one of the preceding claims, characterized in that the tempered flue gas flow with respect to its flow direction upstream of its junction in the

Drying device and / or drying system (12) a steam-suspendable heat exchanger (23), which is acted upon by 5 drawn from a steam turbine of a turbo set tap steam and / or solar generated steam and / or produced in a Fresnelsystem steam, flows through and tempered here.

19. The method according to any one of the preceding claims, characterized in that the tempered flue gas stream or flue gas partial flow with respect to its flow direction upstream of his0 confluence with the drying device and / or drying plant (12) and in particular downstream of the flue gas desulphurisation plant (9), air, in particular after flowing through a / the air preheater (7), which is flowed through in countercurrent from the exhaust gas flue gas flow of the combustion chamber (1) or the steam generator or the furnace, 5 heated air, is mixed.

20. The method according to claim 19, characterized in that in the tempered flue gas stream or flue gas partial stream a temperature between 1 10 ° C and 400 ° C, in particular between 120 ° C and 350 ° C, o preferably between 120 ° C and 200 ° C, is set.

21. The method according to any one of the preceding claims, characterized in that the tempered flue gas stream air is admixed such that in the tempered flue gas stream or flue gas partial stream is adjusted to an oxygen content of 1 to 15% by volume, in particular 1 to 12% by volume,

22, fuel drying plant (15) for carrying out the method according to one of claims 1 - 21 comprising a drying device and / or drying plant (12) with a Brennstoffzuführleitung (13), by means of which the drying device and / or drying plant (12) moister, carbonaceous and particulate Fuel (14) can be fed, and with a Brennstoffabführleitung (3). by means of which fuel (2) dried in the drying device and / or drying plant (12) a storage container (4) and / or burners of a combustion chamber (1) or a steam generator of a power plant (16), preferably a lignite power plant, in particular a dry lignite power plant, and / or a firing system can be fed, wherein

the drying device and / or drying system (12) with a on the

Exhaust side of the combustion chamber (1) or the steam generator or, in particular separate, furnace and / or their respective burners trained flue gas line (6) connected in line and their in the flue gas line (6) guided flue gas in the form of a tempered flue gas stream for drying the wet fuel fed and in particular into the drying device and / or drying plant (12) can be introduced,

characterized,

that the drying device and / or drying plant (12) is arranged in the strand of a flue gas partial flow supply line (11, 11 ', 11 ") branching off from the flue gas line (6) and re-opening into the flue gas line (6).

23. fuel drying plant (15) according to claim 22, characterized in that the drying device and / or drying plant (12) a flue gas partial flow supply line (1 1, 11 ', 11 "), with one on the exhaust side of the combustion chamber (1) or the steam generator and / or the combustion plant and / or the respective burners trained flue gas line (6) is connected in line, has, by means of which the Drying device and / or drying system (12) one of the

Flue gas line (6) diverted, tempered flue gas partial stream can be fed.

24. fuel drying plant (15) according to one of claims 22 to 23, characterized in that the Rauchgasteilstromzuführungsieitung (11) with respect to the flow direction of the flue gas line (6) flowing flue gas stream downstream of a strand of the flue gas line (6) arranged Luftvorwärmers (7) and / or one in the strand of the flue gas line (6) arranged flue gas desulfurization system (9) branches off from the flue gas line (6).

25. fuel drying plant (15) according to any one of claims 22 to 24, characterized in that the Rauchgasteiistromzuführungsleitung (1 ', 1 ") with respect to the flow direction of the flue gas line (8) flowing flue gas stream upstream of the strand of the flue gas line (6). arranged Luftvorwärmers (7) and / or in the strand of the flue gas line (6) arranged flue gas desulphurisation system (9) branches off from the flue gas duct (6).

26. A fuel drying plant (15) according to any one of claims 22 to 25, characterized in that in the flue gas partial flow supply line (1, 1 1 ', 1 1 ") is arranged in particular a steam-heat exchanger (23), which with from a steam turbine of a turbo set of Power plant (16) withdrawn tapping steam and / or solar generated steam and / or can be acted upon with steam generated in a Fresnelsystem and by means of which in the flue gas partial flow supply line (1 1, 11 ', 1 1 ") guided flue gas partial stream is temperature controlled.

27 fuel drying plant (15) according to any one of claims 22 to 26, characterized in that in the flue gas partial flow supply line (11) a first heat displacement system (24) is arranged, which is in operative connection with the flue gas line (6) and by means of which in the flue gas partial flow supply line (1 1) guided flue gas partial stream from the disengaged in the flue gas line (6) guided flue gas stream

Heat energy can be supplied.

28 fuel drying plant (15) according to any one of claims 22 to 27, characterized in that in the flue gas partial flow supply line (11) a second heat transfer system (27) is arranged, which with a branching off of the flue gas line (6) and in particular a therein Luftvorwärmer ( 7) immediate flue gas branch line (26) is in operative connection and by means of which in the flue gas partial flow supply line (11) guided flue gas partial flow from the in the flue gas branch line (26) guided flue gas heat coupled out heat energy can be fed.

29 fuel drying plant (15) according to any one of claims 22 to 28,

characterized in that the flue gas partial flow supply line (1 1, 1 1 ') with at least one of the combustion chamber (1) or the steam generator or the combustion system combustion air supplying combustion air supply line (5) branching first and / or second air supply line (17, 18, 18' ) is in line connection, by means of which / which in the flue gas partial flow supply line (11, 1 ') guided tempered flue gas stream air is immiscible.

30. fuel drying plant (15) according to any one of claims 22 to 29, characterized in that in the flue gas line (6) a third heat displacement system (28) is arranged, which is in operative connection with a / the combustion air supply line (5) and by means of which of the combustion air supply line (5) guided Verbrennungsiuft from the in the flue gas line (6) guided flue gas flow coupled out heat energy can be fed.

31. fuel drying plant (15) according to any one of claims 22 to 30, characterized in that the drying plant (12) flows through a flow of the tempered flue gas drying device or a flow-through of the tempered flue gas flow drying device and at least one associated and in line with the drying device connected coal grinder (25a, 25b) or as coal mill (25c), in particular beater wheel or racquet mill, is formed.