DE102009053009A1 - CO2 separation from flue gases by chemical scrubbing and apparatus for carrying out the process - Google Patents

Abstract

The invention relates to a method for separating carbon dioxide from a flue gas with the following steps: the flue gas is fed to an absorption unit in which at least part of the CO from the flue gas is absorbed using a liquid absorbent fed to the absorption unit, the liquid absorbent enriched with CO is fed to a desorption unit and heated, whereby at least part of the CO is released from the absorbent, - the released CO is discharged from the desorption unit together with the proportion of absorbent evaporated in the desorption unit and fed to a gas / liquid separation unit, - in the gas / liquid separation unit the gaseous CO is separated from the condensed absorbent. The method according to the invention is characterized in that the released CO together with the proportion of absorbent evaporated in the desorption unit from the desorption unit is first fed as a heat transfer medium to a coal drying unit before it is fed to the gas / liquid separation unit.

Description

The invention relates to a method for CO ₂ separation from power plant exhaust gases (flue gases) with the aid of a chemical wash, and a device for carrying out the method, in particular an adsorption desorption.

State of the art

Due to their elemental composition, the combustion of lignite leads to high mass-related specific CO ₂ emissions. Therefore, it is attempted to separate the resulting from the combustion of carbonaceous fuels CO ₂ and then store it in order not to let it go into the atmosphere. The reason for this effort is the greenhouse effect and the resulting global warming.

There are currently three principal concepts of carbon dioxide capture that differ in the positioning of the separation in the energy conversion process. These are the CO ₂ separation before the energy conversion (pre-combustion), the generation of a CO ₂ -rich flue gas by the energy conversion in an enriched oxygen atmosphere (oxy-fuel), and the CO ₂ separation after the energy conversion (post-combustion ).

The concept of CO ₂ separation after energy conversion has the end-of-pipe problem solution as the advantages that the CO ₂ separation itself has only a small influence on the availability of the energy conversion plant, and the possibility exists to retrofit existing facilities , In most power plants, the flue gas leaves the chimney, with the CO ₂ , accounting for about 15% by volume (depending on the power plant, fuel, firing conditions, etc.), entering the atmosphere.

For the separation of CO ₂ from flue gas, various methods are used, for example the chemical or physical absorption in absorption towers or in membrane contactors or a CO ₂ -selective membrane.

The CO ₂ scrubbing as chemical absorption (CAS = Chemical Absorption System) works as follows. The flue gas is passed through a washing liquid after denitrification and desulfurization and possibly further cooling. This liquid usually contains amines. The CO ₂ can first be bound chemically or physically in the detergent (absorption). Afterwards, the entire cleaning liquid is heated, whereby the CO ₂ separates again from the amines (desorption). The washed-out CO ₂ is almost pure and can then be compressed and possibly transported away to a storage. The amine-containing washing liquid is reusable after heating. For low to moderate CO ₂ partial pressures, a separation of 75 to 90% can be achieved.

The regeneration of the detergent, however, is an energy-consuming process, since the exothermic reaction detergent CO ₂ is reversed by supplying heat. The required heat, which is taken from the power plant process, usually has a detrimental effect on the power plant efficiency.

The enriched with CO ₂ raw gas usually enters from below into the absorber and flows through it to the top. Clean, CO ₂ -depleted detergent (absorbent) is added to the absorption column over the beds and trickles down in countercurrent to the gas. During intensive contact between gas and detergent in the beds, the detergent loads in the direction of the thermodynamic equilibrium with the CO ₂ to be washed out of the gas, so that the flue gas leaves the scrubbing column with reduced CO ₂ content, whereas the detergent is enriched with CO ₂ ,

Before being used again as CO ₂ -depleted washing agent for leaching, it must itself be freed from its CO ₂ loading. The regeneration of the detergent preferably takes place at elevated temperature, so that, for reasons of energy optimization, a first heat exchanger heats the laden detergent and at the same time cools the warm, regenerated and thus again CO ₂ -emitted detergent. Further heating of the absorbent can take place either in a heater before the desorber or in another apparatus which is located at the bottom of the regenerating. The heated detergent trickles down in the desorber over the bed, whereby a part of the CO ₂ goes back into the gas phase and rises in the desorber upwards.

At the head of the desorber, the gaseous CO ₂ is cooled by a further heat exchanger, whereby evaporated detergent is condensed out and returned via a line in the desorption process. If necessary, water introduced into the process with the raw gas can also be discharged here.

Alternatively or additionally, desorption can be carried out by lowering the pressure with the aid of a vacuum pump arranged at the head of the desorber.

The CO ₂ -depleted detergent from the bottom of the regeneration column can now in Absorber be loaded again. For this purpose, it is to cool to absorber temperature, which is used in addition to the detergent countercurrent usually a second heat exchanger with cooling water.

Depending on the binding forces between the transition component and the absorption liquid act, one speaks of physical or chemical detergents. Liquids in which both types of binding occur in relevant order of magnitude are called hybrid detergents.

So far, detergents, in particular amine-based solvents are known, for example, diethanolamine, triethanolamine, activated methyldiethanolamine and monoethanol amine. From mono-ethanol-amine (MEA) it is known that a high desorption temperature of about 120 to 130 ° C is necessary due to the strong binding effect between CO ₂ and MEA. This energy requirement must be additionally provided by the power plant and thus adversely reduces the efficiency by about 11 to 13 percentage points.

On a pilot plant scale, alternative detergents are currently being investigated that would require less regeneration energy due to their lower heat capacity and / or lower absorption enthalpy. For example, the Technical University of Dresden is testing the detergent GenosorbN, which, according to the current state of affairs, suggests significant energy savings.

State of the art lignite drying

The brown coal contains up to 60% by weight of water. For the evaporation of the water contained in the coal 15 to 20 wt .-% of the fuel quantity are necessary in the conventional lignite power plants depending on the water content of lignite. Therefore, this fuel quantity of steam generation and thus the power generation is no longer available. Also for the application of CO ₂ separation (regardless of the deposition concept), the lignite should be dried.

Currently, the lignite is dried with hot flue gases at a temperature of 900 to 1000 ° C, the flue gases are withdrawn from the furnace. However, in order to increase the efficiency of the lignite-fired power plants, it would be advantageous to dry the lignite at a lower temperature level.

Various drying and dewatering processes have already been developed for use in power plants, for example the fluidized-bed dryer in which the carbonic acid evaporates as it passes through the fluidized bed. In the drying processes currently under development, the energy required for drying is usually provided by a steam-heated heat exchanger. In addition to heating steam at 10 to 12 bar, alternatively and preferably, heating steam can also be taken from a low-pressure turbine at only about 3 bar, which is available at about 133 ° C. for drying the brown coal. The drying takes place at a pressure of about 1.1 bar and at a fluidized bed temperature of about 110 ° C in almost pure steam atmosphere.

Part of the heat of the evaporated water from lignite can be recovered by using the vapors (steam from lignite drying) either for boiler feedwater pre-heating or also for lignite drying. In the first case described, steam extraction from the steam power process is necessary for coal drying. In the second described part, the vapors must be recompressed with a compressor for coal drying, so that a temperature gradient between the cooled vapors and the water to be evaporated from the lignite is given. Despite the heat recovery lignite drying is an energy-consuming process due to the steam extraction or due to the repeated compression of the vapors.

Task and solution

The object of the invention is to provide a further method for the effective reduction of CO ₂ emissions from the exhaust gases of combustion plants, which is overall more energy efficient and thus cheaper than before.

Furthermore, it is the object of the invention to provide a suitable device for carrying out the aforementioned method.

The objects of the invention are achieved by a method according to the main claim and by a device with the entirety of the features of the independent claim. Advantageous embodiments are shown in the respective dependent claims.

Subject of the invention

The invention relates to a combined method for reducing CO ₂ emissions from the exhaust gases of combustion plants, in particular from flue gases of energy conversion plants, with an integrated coal drying, especially a lignite drying. Furthermore, the invention relates to a device suitable for carrying out this method.

In the following, the term firing plant is understood to mean any plant in which a gaseous, liquid and / or solid fuel is oxidized to utilize the heat generated. These include, for example, gas burners, which are operated with natural gas, liquefied petroleum gas, city gas or landfill gas, oil burners, the z. B. with petroleum, fuel oil, or alcohols are operated, and also grate firing for particulate fuels, such as gas-rich coal or woodchips, fluidized bed or dust firing.

Flue gas is the gaseous combustion product produced during the technical combustion of fuels. Flue gases usually include solid, liquid and / or gaseous impurities such as nitrogen, carbon dioxide, sulfur dioxide, nitrogen oxide and water vapor as gases, solid particles such as fly ash and soot, and optionally also carbon monoxide or hydrogen.

The idea of the invention is based on providing improved and more effective CO ₂ separation from a flue gas by means of chemical absorption compared to the prior art, in which coal drying is integrated for the more effective energy yield of this process and taking advantage of synergy effects. For this purpose, a cooling step required in the CO ₂ separation from a flue gas is advantageously used to at least partially dry coal, in particular moist brown coal.

According to the invention, the CO ₂ separation takes place from the flue gas by means of chemical scrubbing. After chemical (or physical) CO ₂ binding in a suitable detergent (absorbent), the CO ₂ -rich wash solution is passed into a desorption column. By heating the CO ₂ -rich wash solution, the absorbed CO _{2 is} expelled from the wash solution. The heating of the washing solution can be effected, for example, by a heat exchanger operated with low-pressure steam taken from the turbines. As a rule, part of the washing solution, in particular water, is evaporated together with CO ₂ . The amount of the evaporated wash solution varies depending on the operating conditions of the process, in particular temperature, pressure, CO ₂ loading of the wash solution. As washing solutions, in particular amine-based liquids are suitable. For the separation of the CO ₂ from the evaporated washing solution a cooling and a subsequent gas / liquid separation are provided regularly. The previous cooling is required so far as the most effective separation, in other words the purest possible CO ₂ stream, is desired. The lower the temperature selected during the gas / liquid separation, the more completely the previously evaporated wash solution can condense out again.

The idea underlying the invention is now, instead of or at least in addition to this cooling provided so far, which is usually accomplished with a coolant to integrate a further heat-absorbing process, in particular to integrate at this point a coal drying. Coal drying, especially when drying moist brown coal, requires energy in the form of heat.

According to the teaching of the invention, the gaseous CO _{2 released} together with the adsorption unit evaporated in the desorption unit (scrubbing solution) is withdrawn at the top of the desorption unit (column head) and fed to a coal drying unit, in particular a lignite drying unit. The released CO ₂ and the vaporized absorbent often have an overpressure on leaving the desorption unit. Typical pressure conditions are between 1 and 8 bar, in particular between 2 and 6 bar. The temperatures required for the desorption (release) of the CO ₂ from the absorbent are generally well above 100 ° C. for amine-based washing solutions. Accordingly, the CO ₂ liberated, together with the fraction of absorbent evaporated in the desorption unit, when leaving the desorption unit usually has temperatures of more than 100 ° C., in particular more than 120 ° C., and advantageously more than 130 ° C.

This heated and possibly pressurized mixture is advantageously suitable to be used as a heat transfer agent for the process of coal drying. For this purpose, the invention provides for the released CO _2, together with the vaporized in the desorption unit of absorbent, which is discharged from the desorption, direct to a coal drying unit to be used there at least for partial drying of the coal. Advantageously, this mixture acts as a medium for a heat exchanger, which is arranged in the coal drying. For example, this heat exchanger fed by the mixture is placed directly in the fluidized bed of a fluidized bed dryer of a coal drying unit. In addition, other heat exchangers, for example, with steam-operated heat exchangers, as previously customary be arranged within the coal drying unit.

The condensation of the evaporated washing solution takes place at a corresponding pressure regularly at a temperature which is above the temperature of the coal drying, so that the water contained in the coal at least partially evaporated.

Nevertheless, during the heat transfer to the coal to be dried, at least some condensation of the vaporized absorbent may already occur.

The actual separation of the gaseous CO ₂ from the absorbent takes place regularly in the downstream gas / liquid separation unit. The lower the temperatures in the gas / liquid separation unit, the better the degree of separation. Depending on the conditions, the mixture can be fed directly to the gas / liquid separation unit after passing through the coal drying unit, or, if necessary, also be further cooled before.

The condensed wash solution from the heat exchanger is separated after passing through the coal dryer from CO ₂ -rich gas stream and returned to the washing solution treatment. If necessary, the washing solution can be prepared beforehand and, if appropriate, appropriately tempered via a further heat exchanger.

The evaporated water from the coal drying (vapors) can be used as previously for feedwater heating, district heating or for another purpose. Part of the resulting water vapor can be used for direct turbulence of the brown coal to be dried and for the production of the floating fluidized bed or in addition as a heat exchanger to support the brown coal drying process.

In addition to this advantageous embodiment of the invention, it is also conceivable in principle, auszuschleusen the heat for lignite drying at another point from the adsorption / desorption, for example, by the heated regenerated wash solution is first used for lignite drying before they are used for preheating of CO ₂ - loaded wash water before the desorption column is used.

The advantage of the invention is that a large part of the energy for coal drying, in particular completely or partly by the waste heat from the CO ₂ reduction process can be provided, in particular by the heat, for the desorption of CO ₂ from the loaded wash water is needed. Due to the condensation of the evaporated washing solution outside the desorption column, it is advantageously possible to cover the energy required for drying the coal at least partially. As a result, on the one hand eliminates the amount of cooling water to cool the wash solution or at least reduced, and on the other hand, less energy from other processes, in particular in the form of steam from the turbine to be decoupled for drying the lignite. In total, this leads to a significant increase in power plant efficiency.

Special description part

In the following, the invention will be explained in more detail with reference to exemplary embodiments, without this limiting the scope of protection. The person skilled in the art can readily recognize analogous modifications in these as belonging to the invention.

LIST OF REFERENCE NUMBERS

a

CO₂-haltiges Rauchgas,

b

CO₂-abgereichertes Abgas,

c

mit CO₂-angereicherte Waschflüssigkeit (Absorptionsmittel),

d

regenerierte, CO₂-abgereicherte Waschflüssigkeit,

e

verdampfte Waschflüssigkeit mit CO₂,

f

kondensierte Waschflüssigkeit mit CO₂

g

abgetrenntes, gasförmiges CO₂

h

kondensierte und vom gasförmigen CO₂ abgetrennte Waschflüssigkeit

i

feuchte Roh-Braunkohle

j

getrocknete Braunkohle

k

Dampf

l

Kondensat

m

Brüden

n

Brüdenkondensat

1

Absorptionseinheit

2

Desorptionseinheit

3a, 3b

Trenneinheit gasförmig/flüssig

4

Kohletrocknungseinheit

WT1–WT7

Wärmeaustauscher

Fig. 1 to Fig. 4:

a

CO ₂ -containing flue gas,

b

CO ₂ -depleted offgas,

c

with CO ₂ -enriched washing liquid (absorbent),

d

regenerated, CO ₂ -depleted washing liquid,

e

evaporated washing liquid with CO ₂ ,

f

condensed scrubbing liquid with CO ₂

G

separated, gaseous CO ₂

H

condensed and separated from the gaseous CO ₂ washing liquid

i

moist raw lignite

j

dried lignite

k

steam

l

condensate

m

vapors

n

vapor condensate

1

absorbing unit

2

desorption

3a, 3b

Separating unit gaseous / liquid

4

Coal drying unit

WT1 WT 7

heat exchangers

The 1 1 shows the scheme of an energy conversion process, here a power generation in a coal power plant with the CO ₂ separation from the flue gas (decarbonization) by means of chemical scrubbing (eg 30% aqueous solution of monoethanolamine) after the flue gas cleaning according to the current state of the art , The flue gas cleaning of a fired with a solid fuel and the current state of the art large combustion plant includes the denitrification, dedusting and desulfurization in this order. The chemical wash separates 90% of the CO ₂ contained in the flue gas (a) with a purity of 99% by volume (g). Due to the regeneration of the scrubbing solution and the electrical consumption of the decarbonization unit, the power plant net efficiency is reduced by 10 percentage points in a defined design case.

From a ton of raw lignite with a water content of 60 wt .-% and a carbon content of 68.3 wt .-% water and ash-free about 974.686 kg of CO _{2 are} released. At a specific energy requirement of 4 MJ / kg CO ₂ , approximately 3,898 GJ of heat is needed during regeneration. Subsequently, this heat is then removed in the warmed and evaporated wash solution together with the released CO ₂ via heat exchangers to cool the wash solution for re-use and for the purpose of concentration of CO ₂ .

In detail, in 1 a washing process reproduced from the prior art. The raw flue gas (a) loaded with CO ₂ is absorbed by an absorption unit ( 1 ), which flows through it from bottom to top. Here it applies to the washing solution (d) (absorbent), often an aqueous solution of amines, which at the head of the absorption unit ( 1 ) is added and receives the CO ₂ from the flue gas in countercurrent. The CO ₂ -saturated wash solution (c) is placed in a desorption unit ( 2 ), where it is heated to about 120 ° C (WT1). At these temperatures, the CO ₂ (desorbed) dissolves again from the wash solution. The released CO ₂ , together with the evaporated wash solution (s) from the desorption unit ( 2 ) and cooled (WT4). That in a gas / liquid separation unit ( 3a ) separated CO ₂ (g) is now present in high purity, while the separated condensed wash solution (h) to the desorption unit ( 2 ) is returned. The in the desorption unit ( 2 ) freed from CO ₂ washing solution is cooled (WT1, WT2) and again the absorption unit ( 1 ), where the washing process starts again.

In 2 the scheme of a brown coal drying process with vapor condensation of the prior art is shown. The wet coal (i) is fed to a coal drying unit ( 4 ). A heat exchanger operated with steam (k) ensures the heat transfer necessary for the drying of the moist coal, so that it is predominantly dried from the coal drying unit ( 4 ) can be removed as dried coal (j). The steam already partially condenses in this process (1). Part of the vapors (m) is used to agitate the fluidized bed in the coal drying unit ( 4 ), another part after cooling (WT5) condensed out (s). For a lignite with a water content of 60% by weight, a coal temperature of 11 ° C and residual water content in the dry lignite of 12% by weight, approximately 205 MJ will have to be spent on coal heating and about 1.245 GJ on coal drying.

When in 3 represented, also known from the prior art, lignite drying process with Brüdenrekompression be used for the recompression of vapors (552 kg) from one ton of raw lignite from 1 to 2.5 bar about 110 MW electrically. In this version, the heat of the vapors is used after compression as a heat exchanger for coal drying.

In 4 the scheme of an energy conversion process with the inventive combined method for reducing CO ₂ emissions from flue gases of energy conversion plants with integrated coal drying is shown.

After possibly denitrification, dedusting, desulfurization and possibly further cooling, the flue gas (a) of the absorption unit ( 1 ). Where (a) is washed out, the CO ₂ by means of the washing solution (d) from the CO ₂ -containing flue gas. The CO ₂ depleted flue gas (b) leaves the absorption column ( 1 ). The scrubbing solution (c) enriched with CO ₂ passes through a heat exchanger (WT1) into the desorption unit after preheating ( 2 ), where under CO ₂ heating is released again. The liberated gaseous CO ₂ and the evaporated washing solution (e) leave together the desorption column ( 2 ) with a positive pressure, and are a heat exchanger (WT6) a coal drying unit ( 4 ). The condensation of the evaporated washing solution takes place regularly at a temperature which is above the temperature of the coal drying, so that the water contained in the coal evaporates as vapors (m). The scrubbing solution freed from CO ₂ leaves the desorption unit ( 2 ), is cooled (WT1 and optionally WT2) and again the absorption unit ( 1 ).

After passing through the heat exchanger (WT6) in the coal drying unit ( 4 ), an optionally at least partially condensed scrubbing solution and a CO ₂ -rich gas stream (f) are present, which are then dissolved in a gas / liquid separation unit ( 3a ) is separated into a liquid washing solution (h) and a gaseous CO ₂ phase (g).

There are two alternatives available for this, which can also be used cumulatively if necessary.

In a first embodiment of the invention, the CO ₂ leaving the coal drying unit is mixed with that in the desorption unit ( 2 ) evaporated wash solution directly to a gas / liquid separation unit ( 3a ). There, the separated condensate of the washing solution (h) directly back to the desorption unit ( 2 ). The separated CO ₂ -rich gas stream (g) is fed to a further treatment. The gas / liquid separation takes place here without further cooling of the mixture at a high temperature level. The separated under these conditions CO ₂ disadvantageously still has a significant proportion of water. However, the separated washing solution still has such a high temperature level that it can be returned directly to the desorption unit.

In a further alternative, the CO ₂ leaving the coal drying unit is mixed with that in the desorption unit ( 2 ) evaporated wash solution initially cooled (WT7) and only then a gas / liquid separation unit ( 3b ). The gas / liquid separation in this case is such that the proportion of water still present in the separated CO ₂ stream can be significantly lowered. However, the condensed wash solution now has such low temperatures that a direct use in the desorption unit makes little sense energetically. Therefore, the wash solution in this case is directly or via a further cooling (WT2) of the absorption unit ( 1 ).

Depending on the framework conditions and circulation of the washing solution, a procedure may also be advantageous in which both paths indicated above are taken simultaneously. By a control, the proportions for a direct return to the desorption unit or to the absorption unit could advantageously be regulated directly as required.

The evaporated water from the coal drying (vapors) can be used for feedwater heating, district heating or for any other purpose. After the heat release the vapor condensate is optionally fed to the water treatment. Part of the resulting water vapor can be used as in the prior art for turbulence of the brown coal to be dried and for the production of the floating fluidized bed.

When using the waste heat from the washing unit according to the invention in the drying of coal can be advantageous to dispense with the removal of the steam for drying coal completely or partially, or the energy-consuming recompression of the vapors are saved.

In particular, by the use of lignite dried by this type in the power plant process, an efficiency gain of up to 4% points can be achieved. Taking into account the losses from the CO ₂ separation results in a loss of efficiency of only 6 percentage points for the entire process.

Claims (16)

A method of separating carbon dioxide from a flue gas by the steps of: - the flue gas is supplied to an absorption unit in which at least part of the CO _{2 is} absorbed from the flue gas by means of a liquid absorbent supplied to the absorption unit, - the CO ₂ -enriched liquid absorbent fed to a desorption and heated, wherein at least a portion of the CO _{2 is released} from the absorbent, the released CO ₂ is discharged together with the vaporized in the desorption unit portion of absorbent from the desorption, and fed to a gas / liquid separation unit, - Gas / liquid separation unit, the gaseous CO _{2 is separated} from the condensed absorbent, characterized in that the liberated CO ₂ together with the vaporized in the desorption unit portion of absorbent from the desorption first as a heat carrier of a Koh lethal drying unit is supplied before it is fed to the gas / liquid separation unit. A method according to claim 1, wherein lignite is dried in the coal drying unit. The method of claim 1 to 2, wherein the separated CO _{2 is} fed together with the vaporized in the desorption unit absorbent to a heat exchanger within the coal drying unit, and heat is delivered to the coal to be dried. The method of claim 1 to 3, wherein the vaporized absorbent at least partially condensed by the heat release in the coal drying unit. The method of claim 1 to 4, wherein the released CO _{2 is} discharged together with the vaporized in the desorption unit portion of absorbent under pressure from the desorption. The method of claim 1 to 5, wherein the released CO ₂ together with the vaporized in the desorption unit of absorbent on leaving the desorption has a pressure between 1 and 8 bar, in particular between 2 and 6 bar. The method of claim 1 to 6, wherein the released CO ₂ together with the vaporized in the desorption unit of absorbent on leaving the desorption unit temperatures of more than 100 ° C, in particular more than 120 ° C, and advantageously more than 130 ° C. , The method of claim 1 to 7, wherein the released CO _{2 is} fed together with the vaporized in the desorption unit of absorbent after leaving the coal drying unit directly to a gas / liquid separation unit, and the separated there absorbent is returned to the desorption unit. The method of claim 1 to 7, wherein the released CO _{2 is} first further cooled together with the vaporized in the desorption of absorbent after leaving the coal drying unit, a gas / liquid separation unit is supplied, and the absorbent separated there is fed to the absorption unit. The method of claim 1 to 7, wherein the released CO ₂ together with the vaporized in the desorption unit of absorbent after leaving the coal drying unit is both partially fed directly to a gas / liquid separation unit, and the separated there absorbent is returned to the desorption, as Partially further cooled, is also supplied to a gas / liquid separation unit, and there the separated absorbent is supplied to the absorption unit. Device for separating carbon dioxide from a flue gas with an absorber unit ( 1 ), in which flue gas is brought into contact with absorbent, and with a desorption unit ( 2 ), in which CO _{2 is released} from the heated CO ₂ -enriched absorbent, an recirculation loop (c, d) for an absorbent between the absorption unit ( 1 ) and the desorption unit ( 2 ), and another line for vaporized absorbent together with released CO ₂ (e) from the desorption unit ( 2 ) to a gas / liquid separation unit ( 3a . 3b ), characterized in that the line between the desorption unit ( 2 ) and the gas / liquid separation unit ( 3a . 3b ) at least partially as a heat exchanger (WT6) for a coal drying unit ( 4 ) is trained. Apparatus according to claim 11, wherein the coal drying unit is integrated in this apparatus. Apparatus according to claim 11 to 12, with a lignite drying unit. Apparatus according to claims 11 to 13, comprising a condensed absorbent (h) from the gas / liquid separation unit (10). 3a ) to the desorption unit ( 2 ). Apparatus according to claims 11 to 13, comprising a condensed absorbent (h) from the gas / liquid separation unit (10). 3b ) to the absorption unit ( 2 ) as well as with a further heat exchanger (WT7) upstream of the gas / liquid separation unit. Apparatus according to claims 11 to 13, comprising a condensed absorbent line (h) from a first gas / liquid separation unit (10). 3a ) to the desorption unit ( 2 ) and with a line for condensed absorbent (h) from another gas / liquid separation unit ( 3b ) to the absorption unit ( 2 ), and with one of the further gas / liquid separation unit ( 3b ) upstream further heat exchanger (WT7).

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