EP3548587B1 - Method and apparatus for carbon reduction in the bottom product of a fluidised bed gasifier - Google Patents

Description

The present disclosure relates to a plant for converting carbonaceous fuels into synthesis gas comprising a gasification reactor with at least one fluidized bed zone in which the fuels are gasified by suitable gasification means, a carbonaceous ash stream being produced as the bottom product in a bottom area below the fluidized bed zone and with below the gasification reactor a device is arranged in which the bottom product is oxidized by supplying an oxidizing agent. The subject matter of the invention is defined in the claims.

Processes for converting carbonaceous fuels in the fluidized bed have been known for a long time. In particular, the high-temperature Winkler process (HTW process) should be mentioned here, which is considered a tried and tested technology with which both lumpy and liquid or pasty fuels are converted into synthesis gas. Difficult fuels with a very high ash content and biologically based fuels are also used as fuel. These are introduced into a fluidized bed, which is operated as a bubble-forming fluidized bed, and gasified with oxygen. Compared to other gasification processes, the HTW process works at comparatively moderate temperatures, at which the resulting ash does not leave the gasification reactor in a molten state. This has operational advantages, particularly with corrosive ash.

In the known HTW processes, the gasification usually takes place via separate nozzles with the gasification agents, for example water vapor, carbon dioxide, oxygen or air. These nozzles are arranged, for example, in different levels, for example both in the fluidized bed zone and in the so-called freeboard zone (FB). In this freeboard zone (FB), a high material and energy transfer rate is achieved and by returning the unconverted solids via the cyclone and return line to the fluidized bed, a uniform temperature distribution across the fluidized bed can be ensured. To avoid the formation of particle agglomerations, the temperature of the fluidized bed should be kept below the temperature of the ash softening point.

In addition, with the conventional HTW process, gasification agents, usually oxygen, are introduced into the FB zone, which is located above the fluidized bed. By injecting this "secondary" oxygen, various effects are achieved, namely, on the one hand, the conversion of part of the finely divided fuel that is discharged from the fluidized bed and, on the other hand, the temperature of the gases should be increased so that further oxidation and / or the volatile substances (tars and hydrocarbons) expelled from the feedstock can crack. At the same time, the finely distributed fuel _{particles react with steam and CO 2 in} accordance with the Boudouard reaction.

The proportion of total oxygen above the fluidized bed is, for example, between about 60% and about 10% in an HTW process. In order to avoid slagging in the post-gasification zone, the temperatures should preferably not exceed certain limit values, and the operating temperature should preferably be at least about 100 ° C. below the ash softening point. This can be done by mixing steam with oxygen and introducing it into the reactor. However, the addition of oxygen to the post-gasification zone also leads in side reactions to a partial combustion of the synthesis gas reservoir (CO + H ₂ ) and consequently to a reduction in the synthesis gas yield. Therefore, one has to increase the gas and particle temperature in order to accelerate the gasification reaction.

When gasifying fossil fuels containing ash in the high-temperature Winkler gasifier (HTW gasifier) under stationary fluidized bed conditions, a carbonaceous ash stream (so-called bottom product BP) is drawn off at the bottom of the gasifier. In order to utilize the energy and to achieve the landfill suitability, the soil product has been fed to an external furnace. For economic reasons, this complex post-treatment should be avoided.

The need for suitable methods for gasifying carbonaceous fuels such as straw, waste wood, coal or the like is fundamentally increasing. From it there is an increasing need for the development of cost-effective gasification processes in which no additional plants for the disposal of the carbon-containing soil product are required.

In the WO 2015/003778 A1 describes a method and a device for the aftertreatment of the carbon-containing soil product resulting from the gasification of carbon-containing fossil fuels in a high-temperature Winkler process (HTW process) in the direction of gravity below the fluidized bed. It is proposed to use the energy of the soil product and to achieve the landfill suitability not to feed the soil product to an external furnace, but to apply an oxidizing agent to open-pore ceramic elements such as gas purging stones, foam ceramics or the like in a soil product oxidizer below the fluidized bed. In this way, a more extensive oxidation is to be achieved and the carbon conversion in the HTW gasifier is to be increased.

U.S. 4,721,514 A describes a method for gasifying coal using coal powder.

The object of the present invention is to provide an improved device and a method for the economical gasification of different starting materials in a pressurized fluidized bed gasification, which is suitable for comparatively high operating pressures of preferably above 10 bar and is economical with a high level of safety and availability.

• als Einrichtung zur Oxidation des Bodenprodukts unterhalb der Wirbelschichtzone (11) des Vergasungsreaktors (10) eine zusätzliche Wirbelschicht-Brennkammer (12) angeordnet ist,
• wenigstens eine Zuführeinrichtung (27, 28) für die Zufuhr von Sauerstoff und/oder Luft und/oder Dampf und/oder CO₂ in die zusätzliche Wirbelschicht-Brennkammer (12) vorgesehen ist, und
• die Zuführeinrichtung (27, 28) derart ausgebildet ist, dass durch den in die zusätzliche Wirbelschicht-Brennkammer (12) injizierten Sauerstoff- und/oder Luft- und/oder Dampf- und/oder CO₂-haltigen Fluidstrom das in der zusätzlichen Wirbelschicht-Brennkammer (12) zu verbrennende Bodenprodukt fluidisiert wird.

The solution to this problem is provided by a plant for converting carbonaceous fuels into synthesis gas comprising a gasification reactor with at least one fluidized bed zone of the type mentioned at the beginning with the features of claim 1. Thus, the invention relates to a plant for converting carbonaceous fuels into synthesis gas comprising a gasification reactor (10) with at least one fluidized bed zone (11) in which the fuels are gasified by suitable gasification means, a carbonaceous ash stream being obtained as the bottom product in a floor area below the fluidized bed zone (11) and wherein a device is arranged below the gasification reactor (10) in which the bottom product is oxidized by supplying an oxidizing agent, characterized in that

• an additional fluidized bed combustion chamber (12) is arranged as a device for the oxidation of the bottom product below the fluidized bed zone (11) of the gasification reactor (10),
• at least one feed device (27, 28) is provided for feeding oxygen and / or air and / or steam and / or CO ₂ into the additional fluidized bed combustion chamber (12), and
• the feed device (27, 28) is designed in such a way that the oxygen and / or air and / or steam and / or CO ₂ -containing fluid flow injected into the additional fluidized bed combustion chamber (12) causes the fluid flow in the additional fluidized bed combustion chamber (12) to Combustion chamber (12) to be burned bottom product is fluidized.

The invention as a whole is defined by the claims.

According to the invention, an additional fluidized bed combustion chamber is arranged as a device for oxidizing the bottom product below the fluidized bed zone of the gasification reactor. In this additional fluidized bed combustion chamber, an effective combustion of the bottom product from the gasification reactor can be achieved by supplying a suitable oxidizing agent. The reactor forming the additional fluidized bed combustion chamber is preferably somewhat smaller than the gasification reactor.

This additional fluidized bed combustion chamber is positioned below the gasification reactor and is connected to the fluidized bed zone of the gasification reactor, for example via a cross-sectional constriction.

The oxidizing agent, which is fed into the additional fluidized bed combustion chamber via the at least one feed device, preferably sprayed or injected, preferably comprises oxygen and / or air and can additionally contain, for example, steam and / or CO ₂ . If several feed devices are used, oxidizing fluid streams with different compositions can be fed from one or several of the aforementioned gases / fluids are fed to the additional fluidized bed combustion chamber.

The oxygen content of the oxidizing agent, when this is fed in as a mixture with steam, is preferably less than about 21% by volume. The oxygen content and the amount of oxygen should be selected depending on the amount of carbon in the bottom product to be burned in the additional fluidized bed combustion chamber and the combustion temperature below the ash softening.

A preferred development of the invention provides that the system has at least one temperature measuring device for measuring the temperature in the additional fluidized bed combustion chamber. This temperature measuring device can be used to measure the temperature in the additional fluidized bed combustion chamber and, depending on the temperature measured, the carbon content of the fuel can be deduced and the oxygen content of the oxidizing agent supplied can be adjusted accordingly, preferably so that hyperstoichiometric ratios result.

A regulating device is preferably also provided to regulate the amount and / or the oxygen content of an oxygen and / or air and / or steam and / or CO ₂ -containing fluid flow injected into the additional fluidized bed combustion chamber via the at least one feed device .

The control device is preferably in operative connection with the temperature measuring device in order to measure the amount and / or the oxygen content of the oxygen and / or air and / or steam and / or CO _{2 injected into the additional fluidized bed combustion chamber via the at least one feed device} To regulate fluid flow as a function of the measured temperature in the additional combustion chamber.

According to the invention, the feed device is designed such that the bottom product to be burned in the additional combustion chamber is fluidized _{by the oxygen and / or air and / or steam and / or CO 2 -containing fluid flow injected into the additional fluidized bed combustion chamber.} This gives you the procedural one The advantage is that no additional fluid is required for the fluidization, ie for the generation of the fluidized bed in the additional combustion chamber, but rather the oxidizing agent which is supplied in any case can be used for this purpose.

The feed device preferably comprises at least one nozzle, preferably a multi-component nozzle, for injecting a fluid mixture of at least two different oxidizing fluids into the additional combustion chamber. For example, a multi-fluid nozzle can be used here, as shown in the WO 2014/026748 A1 is described. Reference is expressly made here to the content of this publication.

Furthermore, at least one valve for shutting off and / or regulating the oxidizing fluid flow fed in is preferably assigned to the feed device, so that the feed of the oxidizing agent can be regulated and / or shut off if necessary.

According to a preferred development, the system according to the invention comprises at least two supply devices for supplying differently composed oxidizing fluid flows, each supply device being assigned at least one valve for shutting off and / or regulating the respectively supplied oxidizing fluid flow. In this way, fluid streams with different compositions can be fed to the additional fluidized-bed combustion chamber, possibly differentiated at different points, in the respectively desired amount.

The system according to the invention preferably comprises at least one pressure difference measuring device and display device in order to display a pressure difference between the pressure in the fluidized bed of the gasification reactor and the pressure in the additional fluidized bed combustion chamber. The measured pressure difference can be used, for example, to optimize the conditions for the fluidization of the fluidized bed in the gasification reactor due to the flue gases emerging from the additional fluidized bed combustion chamber on the one hand and the oxidizing agent supplied on the other.

A preferred further development of the system according to the invention provides that it has at least one connecting line for the return of raw gas from the gasification reactor, the one from the gasification reactor and into the additional one Introduces fluidized bed combustion chamber. In this way, at least a partial flow of the raw gases generated in the gasification reactor can be returned to the additional fluidized bed combustion chamber and used there, for example, for fluidization (generation of the fluidized bed) and / or possibly also for oxidation and promotion of combustion, provided the raw gas is still Contains oxidizing gas components.

A preferred further development of the system according to the invention comprises at least one compressor for compressing the raw gas that is returned from the gasification reactor into the additional fluidized bed combustion chamber, so that the raw gas can be compressed for the return.

The subject of the present disclosure, but not of the invention to the extent described, is also a method for converting carbonaceous fuels into synthesis gas in which the fuels are gasified by suitable gasifying agents in a gasification reactor with at least one fluidized bed zone, with a floor area located below the fluidized bed zone a carbonaceous ash stream is obtained as the bottom product and a device is arranged below the gasification reactor in which an oxidation of the bottom product takes place by supplying an oxidizing agent, the oxidation of the bottom product taking place in an additional fluidized bed combustion chamber arranged below the fluidized bed zone of the gasification reactor.

• die Oxidation des Bodenprodukts in einer unterhalb der Wirbelschichtzone (11) des Vergasungsreaktors (10) angeordneten zusätzlichen Wirbelschicht-Brennkammer (12) erfolgt, und
• über mindestens eine erste Zuführeinrichtung (27) in die zusätzliche Wirbelschicht-Brennkammer (12) ein oxidierender Fluidstrom injiziert wird, welcher Sauerstoff und/oder Luft und/oder Dampf enthält und über mindestens eine zweite Zuführeinrichtung (28) in die zusätzliche Wirbelschicht-Brennkammer (12) ein Fluidstrom injiziert wird, welcher CO₂ und/oder recyceltes Gas aus dem Vergasungsreaktor (10) enthält.

The invention also relates to a method for converting carbonaceous fuels into synthesis gas, in which the fuels are gasified by suitable gasifying agents in a gasification reactor (10) with at least one fluidized bed zone (11), with a floor area below the fluidized bed zone (11) as Bottom product, a carbonaceous ash stream is obtained and a device is arranged below the gasification reactor (10) in which the bottom product is oxidized by supplying an oxidizing agent, characterized in that

• the oxidation of the bottom product takes place in an additional fluidized bed combustion chamber (12) arranged below the fluidized bed zone (11) of the gasification reactor (10), and
• An oxidizing fluid stream containing oxygen and / or air and / or steam is injected into the additional fluidized bed combustion chamber (12) via at least one first supply device (27) and into the additional fluidized bed combustion chamber (28) via at least one second supply device (28). 12) a fluid stream is injected which contains CO ₂ and / or recycled gas from the gasification reactor (10).

Preferably, according to the invention, the flue gas resulting from the oxidation of the bottom product in the additional fluidized bed combustion chamber is fed from the underside into the gasification reactor and serves to generate fluidization of the particles to be gasified or at least to support this fluidization.

According to a preferred development of the method according to the invention, part of the raw gas generated during gasification in the gasification reactor is returned from the gasification reactor via at least one connecting line to the additional fluidized bed combustion chamber.

The recirculated part of the raw gas generated during the gasification in the gasification reactor is preferably compressed by means of at least one compressor before it is introduced into the additional fluidized bed combustion chamber.

A preferred development of the method provides that the exit velocity of the bottom product from the gasification reactor into the additional fluidized bed combustion chamber located below is preferably adjusted with the aid of the flow of the recirculated gas in such a way that only particles of coarser particle size due to gravity from the gasification reactor into the one below get additional fluidized bed combustion chamber. The finer class of particles therefore remains in the gasification reactor, which also reduces the carbon content.

The method according to the invention provides that the fuel is preferably gasified in the gasification reactor at an operating pressure of at least approximately 10 bar. According to the invention, an oxidizing fluid flow containing oxygen and / or air and / or steam is injected into the additional fluidized bed combustion chamber via at least one first supply device, and a fluid flow containing CO ₂ and / or contains recycled gas from the gasification reactor.

It is advantageous to measure the temperature in the additional fluidized bed combustion chamber, since the temperature allows conclusions to be drawn about the course of the combustion process and the carbon content of the bottom product there after the gasification process. In this way, depending on the measured temperature, the oxygen content of the oxidizing agent fed to the fluidized bed combustion chamber can be set in accordance with the carbon content of the fuel, with conditions preferably being set above stoichiometric.

The gasification reactor used for gasification in the fluidized bed zone according to the present invention is particularly preferably a high-temperature Winkler gasifier and the gasification process is carried out under appropriate conditions with regard to pressure, temperature and other parameters, reference being made here to the publication mentioned above and the relevant literature becomes.

• Figur 1 eine schematisch vereinfachte Darstellung einer beispielhaften erfindungsgemäßen Anlage;
• Figur 2 eine vergrößerte Detaildarstellung eines Ausschnitts aus der in Figur 1 dargestellten Anlage, wobei der untere Bereich des Vergasungsreaktors und die zusätzliche Wirbelschicht-Brennkammer dargestellt sind.

The present invention is explained in more detail below on the basis of exemplary embodiments with reference to the accompanying drawings. Show:

• Figure 1 a schematically simplified representation of an exemplary system according to the invention;
• Figure 2 an enlarged detailed representation of a section from the in Figure 1 shown plant, the lower area of the gasification reactor and the additional fluidized bed combustion chamber are shown.

In the following, reference is first made to FIG Figure 1 a possible embodiment of the present invention explained in more detail. The illustration shows a schematically simplified illustration of an exemplary system according to the invention, the a conveyor system 20 by means of which the starting material, for example coal, biomass, waste or the like, is fed to the gasification reactor 10. This conveying and supply system 20 comprises, for example, a number of conically ending containers 21 and optionally locks and is suitable for bringing the starting material to a pressure level that also prevails in the gasification reactor 10. For example, the material can then be brought into the gasification reactor via a screw conveyor 22.

The gasification reactor 10 comprises a fluidized bed zone 11 and above a so-called "free board zone", ie a mixing area 16 (also called freeboard zone), in these two zones 11, 16 the gasification of the starting material at elevated temperatures of, for example, about 800 ° C to about 1200 ° C takes place with the supply of a mixture of oxygen and steam or air. Furthermore, a cyclone separator 18 connected to the gasification reactor 10 is provided, in which the entrained partially gasified particles (ash particles) are separated from the synthesis gas generated in the gasification reactor so that the dust-free synthesis gas can be discharged via an outlet line 19. A return line 23 is provided, which starts from the lower region of the cyclone separator 18 and serves to return ash particles entrained with the synthesis gas, which were separated in the cyclone separator 18, into the fluidized bed zone 11.

In the process according to the invention, solid by-products (ash particles) from the bottom product of the gasification reactor 10 reach an additional fluidized bed combustion chamber 12, which is arranged below the fluidized bed zone 11 of the gasification reactor 10 and is connected to it via a cross-sectional constriction, so that particles of the bottom product, in particular due to gravity can fall from the gasification reactor 10 downwards into the additional fluidized bed combustion chamber 12, while lighter, smaller particles remain in the gasification reactor 10 due to the fluidization. How to get in Figure 1 recognizes, the additional fluidized bed combustion chamber 12 is much smaller than the gasification reactor 10 and is only a fraction of the size of the gasification reactor.

How to continue dating Figure 1 recognizes, the addition of the oxidizing agent, which _{consists in particular of oxygen / steam, air or CO 2} , can take place in different areas of the system at different height positions. In the embodiment according to Figure 1 For example, a first upper nozzle 24 for adding the oxidizing agent to the gasification reactor is provided in the lower region of the "free board zone". Furthermore, a mixture of oxygen and steam, for example, is added below it into the fluidized bed zone 11 of the gasification reactor via a second central nozzle 25 and a third central nozzle 26. Finally, this or another oxidizing agent of one of the compositions described above is added via a fourth lower nozzle 27 is provided, which takes place directly into the additional fluidized bed combustion chamber 12. These various nozzles for the supply of the oxidizing agent can in the simplest case be connected to one another via lines when using oxidizing agents of the same composition and fed via common supply lines, but a supply from different sources via separate line systems is equally possible.

The combustion residue that exits from the additional fluidized bed combustion chamber 12 located below the gasification reactor 10, preferably downwards, is removed from the system, for example, via a water-cooled system of screw conveyors 38 and pressure vessels 39, in which it is cooled and brought to ambient pressure.

The area of the plant in which the additional fluidized bed combustion chamber 12 is located is shown below by way of example on the basis of the enlarged detailed illustration according to FIG Figure 2 explained in more detail. In principle, only the additional fluidized bed combustion chamber 12 and partially the fluidized bed zone 11 of the gasification reactor lying above it can be seen here. A first upper feed device 24 can be seen in the form of a nozzle or the like for, for example, a mixture of oxygen and steam, which is injected into the fluidized bed zone 11 of the gasification reactor.

In the area of the cross-sectional constriction 13 provided between the two system parts 11 and 12, a further central feed device 26 is arranged, via which, in this case, a mixture of recycled raw gas and CO ₂ from the Gasification reactor is fed, which is used here to support the fluidization of the material to be gasified in the fluidized bed zone 11. A further lower nozzle 27 is provided, which is arranged on the outside of the additional fluidized bed combustion chamber 12 and via which oxidizing agent such as a mixture of oxygen and steam can be fed into the additional fluidized bed combustion chamber 12.

In the embodiment according to Figure 2 Another lower nozzle 28 is arranged in the lower region of the additional fluidized bed combustion chamber 12, via which, for example, a mixture of recycled raw gas from the gasification _{reactor and CO 2} can be injected into the additional fluidized bed combustion chamber. In this way, the combustion residues / ash particles can be fluidized in the additional fluidized bed combustion chamber 12 and thus a fluidized bed can be formed. A line 29, in which a valve 30 is arranged, leads to this nozzle 28, so that the supply to the nozzle 28 can be regulated and, for example, shut off or throttled. This line 29 is connected to a line from which a branch line 31 branches off, which leads to the nozzle 26, so that a gas mixture from the gasification reactor can be used for fluidization in both parts of the plant, which is fed from the latter via a common line, which then branches off and leads to the nozzles 26 and 28, respectively. A valve 32 is also arranged in the branch line 31, so that this branch line 27 can be shut off separately if, for example, only a supply to the nozzle 28 is desired. It is also possible via a further valve 35 to shut off the line before the branch line 31 branches off or _{to regulate the supply of raw gas and CO 2} for both lines 29, 31 already there.

Furthermore, a temperature measuring device 33 is provided, by means of which the temperature in the additional fluidized bed combustion chamber 12 can be measured. The measured temperature can be used to draw conclusions about the carbon content of the fuel in the combustion chamber 12, from which it is then in turn calculated how much oxidizing agent must be supplied to the combustion chamber 12 via the nozzle 27 in order to achieve an optimal oxygen / carbon ratio (preferably if this is set above stoichiometric)

Furthermore, in Figure 2 a pressure difference measuring device 34 is provided which measures the respective pressure on the one hand in the fluidized bed zone 11 and on the other hand in the additional fluidized bed combustion chamber 12, the pressure difference between the two values being determined and displayed. From this pressure difference, conclusions can be drawn about the flow conditions in the cross-sectional constriction 13 between the two parts of the system. Depending on this, the supply of the fluid via the line 27 and the nozzle 26 into the area of the cross-sectional constriction 13 can then be regulated, which is done, for example, via the valve 32. In this way, one can influence the degree of fluidization of the fluidized bed zone 11 by the recycled raw gas.

List of reference symbols

10

Gasification reactor

11

Fluidized bed zone

12th

Fluidized bed combustion chamber

13th

Cross-sectional constriction

14th

Feeding device

15th

Valve

16

free board zone

17th

Connecting line

18th

Cyclone separator

19th

Output line for synthesis gas

20th

Conveyor system / feed system

21

conical ending containers

22nd

Auger

23

Return line

24

first upper nozzle for oxidizing agent supply

25th

second middle nozzle

26th

third middle nozzle

27

fourth lower nozzle

28

jet

29

management

30th

Valve

31

Branch line

32

Valve

33

Temperature measuring device

34

Differential pressure measuring device

35

Valve

38

Screw conveyors

39

pressure vessel

Claims (15)

1. System for converting carbonaceous fuels into synthesis gas, comprising a gasification reactor (10) which comprises at least one fluidized-bed zone (11) in which the fuels are gasified by means of suitable gasification agents, with a carbonaceous ash flow being produced as a bottom product in a bottom region arranged below the fluidized-bed zone (11), and, below the gasification reactor (10), a means being arranged in which the bottom product is oxidized by supplying an oxidation agent, characterized in that

   - as a means for oxidizing the bottom product, an additional fluidized-bed combustion chamber (12) is arranged below the fluidized-bed zone (11) of the gasification reactor (10),

   - at least one supply means (27, 28) is provided for supplying oxygen and/or air and/or steam and/or CO₂ into the additional fluidized-bed combustion chamber (12), and

   - the supply means (27, 28) is designed such that the fluid flow which contains oxygen and/or air and/or steam and/or CO₂ and is injected into the additional fluidized-bed combustion chamber (12) fluidizes the bottom product to be combusted in the additional fluidized-bed combustion chamber (12).
2. System for converting carbonaceous fuels into synthesis gas according to claim 1, characterized in that the additional fluidized-bed combustion chamber (12) is connected to the fluidized-bed zone (11) of the gasification reactor (10) via a cross-sectional constriction (13).
3. System for converting carbonaceous fuels into synthesis gas according to either claim 1 or claim 2, characterized in that a temperature measuring means (33) is provided for measuring the temperature in the additional fluidized-bed combustion chamber (12).
4. System for converting carbonaceous fuels into synthesis gas according to any of claims 1 to 3, characterized in that at least one regulating means (30, 35) is provided in order to regulate the amount and/or the oxygen content of a fluid flow which contains oxygen and/or air and/or steam and/or CO₂ and is injected into the additional fluidized-bed combustion chamber (12) by means of the at least one supply means (27, 28).
5. System for converting carbonaceous fuels into synthesis gas according to any of claims 1 to 4, characterized in that the regulating means is in operative connection with the temperature measuring means (33) in order to measure the amount and/or the oxygen content of the fluid flow which contains oxygen and/or air and/or steam and/or CO₂ and is injected into the additional fluidized-bed combustion chamber (12) by means of the at least one supply means (27, 28), depending on the measured temperature in the additional combustion chamber (12).
6. System for converting carbonaceous fuels into synthesis gas according to any of claims 1 to 5, characterized in that the supply means (27, 28) comprises at least one nozzle, preferably a multi-substance nozzle, for injecting a fluid mixture consisting of at least two different oxidizing fluids into the additional combustion chamber (12).
7. System for converting carbonaceous fuels into synthesis gas according to any of claims 1 to 6, characterized in that at least one valve (30, 35) for shutting off and/or regulating the supplied oxidizing and/or fluidizing fluid flow is assigned to the supply means (27, 28).
8. System for converting carbonaceous fuels into synthesis gas according to any of claims 1 to 7, characterized in that said system comprises at least two supply means (27, 28) for supplying differently composed oxidizing fluid flows, with in each case at least one valve (30, 35) for shutting off and/or regulating the oxidizing fluid flow supplied in each case being assigned to each supply means.
9. System for converting carbonaceous fuels into synthesis gas according to any of claims 1 to 8, characterized in that

   - said system comprises at least one pressure difference measuring device (34) and display device in order to measure and display a pressure difference between the pressure in the fluidized-bed zone (11) of the gasification reactor (10) and the pressure in the additional fluidized-bed combustion chamber (12); and/or

   - at least one connecting line (29) is provided for returning raw gas from the gasification reactor (10), which line leads at least parts of the generated raw gas flow back into the additional fluidized-bed combustion chamber (12); and/or

   - at least one compressor is provided for compressing returned raw gas from the gasification reactor (10) into the additional fluidized-bed combustion chamber (12).
10. Method for converting carbonaceous fuels into synthesis gas, in which the fuels are gasified by means of suitable gasification agents in a gasification reactor (10) comprising at least one fluidized-bed zone (11), with a carbonaceous ash flow being produced as a bottom product in a bottom region arranged below the fluidized-bed zone (11), and, below the gasification reactor (10), a means being arranged in which the bottom product is oxidized by supplying an oxidation agent, characterized in that

    - the bottom product is oxidized in an additional fluidized-bed combustion chamber (12) arranged below the fluidized-bed zone (11) of the gasification reactor (10), and

    - an oxidizing fluid flow containing oxygen and/or air and/or steam is injected into the additional fluidized-bed combustion chamber (12) by means of at least one first supply means (27) and a fluid flow containing CO₂ and/or recycled gas from the gasification reactor (10) is injected into the additional fluidized-bed combustion chamber (12) by means of at least one second supply means (28).
11. Method according to claim 10, characterized in that the flue gas produced during the oxidation of the bottom product in the additional fluidized-bed combustion chamber (12) is fed from the underside into the gasification reactor (10) and is used there to produce fluidization of the particles to be gasified.
12. Method according to either claim 10 or claim 11, characterized in that part of the raw gas generated during gasification in the gasification reactor (10) is returned from the gasification reactor via at least one connecting line (29) to the additional fluidized-bed combustion chamber (12).
13. Method according to claim 12, characterized in that the returned part of the raw gas generated during gasification in the gasification reactor (10) is compressed by means of at least one compressor before being introduced into the additional fluidized-bed combustion chamber (12).
14. Method according to either claim 12 or claim 13, characterized in that the discharge speed of the bottom product from the gasification reactor (10) into the additional fluidized-bed combustion chamber (12) located below is adjusted, preferably using the flow of the returned gas, such that only particles of a coarser particle size travel from the gasification reactor (10) into the additional fluidized-bed combustion chamber (12) below due to gravity.
15. Method according to any of claims 10 to 14, characterized in that

    - the fuels are gasified in the gasification reactor (10) at an operating pressure of at least approximately 10 bar; and/or

    - the temperature in the additional fluidized-bed combustion chamber (12) is measured and the oxygen content of the oxidation agent supplied to the fluidized-bed combustion chamber (12) is adjusted accordingly depending on the measured temperature.

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