DE102004024672B4 - Apparatus and method for producing a tar-free lean gas by gasification of biomass - Google Patents

Abstract

Carburetor for the gasification of raw material, in particular of biomass, with a carburetor housing, which has arranged one below the other
a drying and pyrolysis zone (1) for drying and pyrolysis of the raw material,
a reduction zone (2) for catalytic cracking and carbon conversion in the raw material and
a post-gasification zone (3) for the post-gasification of carbon still contained in the raw material,
wherein the gasifier comprises a Pyrolyseschwelgasabführeinrichtung (6) for the removal of carbonization gases from the drying and pyrolysis zone (1), a fuel gas discharge means (8) for the removal of carbonization from the Nachvergasungszone (3), one with the Pyrolyseschwelgasabführeinrichtung (6) and the fuel gas discharge means (8 ) connected mixing device (5) for mixing the effluent from the drying and pyrolysis zone (1) exhaust gases and from the Nachvergasungszone (3) discharged carbonization and
a carbonization gas feed unit (7) for directing the carbonization gases mixed in the mixing device (5) into the reduction zone (2),
characterized in that
below the drying and pyrolysis zone (1) in an upper packed bed zone (2e) and above ...

Description

The present invention relates to an apparatus and a method for producing a tar-free lean gas by gasification of biomass, garbage or the like, hereinafter also referred to as fuel or raw material. The purpose of this thermochemical gasification of carbonaceous solid fuels is the production of a tar-free combustible Nutzgases, which can then be supplied to a consumer, such as an internal combustion engine in the form of a gas engine. The device according to the invention makes it possible to operate the process units downstream of the gas generation, such as, for example, the gas engine, without the tar compounds formed during the gasification leading to malfunctions. This is achieved by generating a tar-free, ie a maximum of about 50 mg tar / Nm ³ containing lean gas. In this context, the term "tar" covers all hydrocarbons formed during the gasification, which leave their gaseous state of aggregation when the gas cools down to the temperature required for its use and, along with this change in state, permanently disturbs the overall process in its function.

• • Die Gegenstromvergasung ist zwar vergleichsweise technisch einfach und anspruchslos, produziert jedoch brennbare Nutzgase mit extrem hohen Teergehalten.
• • Auch bei der technisch anspruchsvolleren Gleichstromvergasung gelingt es nur bei sehr kleinen Einheiten, brennbare Nutzgase in ausreichend guter Qualität bzw. ausreichend teerarme brennbare Nutzgase herzustellen. Schon bei Anlagen mit einer elektrischen Leistung von etwa > 50 kW wird es jedoch zunehmend schwieriger, das Brennstoffbett in gleichmäßigem Fluss zu bewegen, so dass bei größeren Anlagen auch hier Teere in zu hoher Konzentration im Produktgas zu finden sind.

Methods for producing tar-free lean gases by gasification of biomass are already state of the art. In addition to flammable useful gas, the processes also produce mixtures of condensable or resublimable hydrocarbons (tars), which are vapor-laden in the gas at the high temperatures during gas production (about> 700 ° C.). For the use of the gas, for example, in aggregates, which serve the purpose of power generation, the combustible useful gas must be cooled, resulting in the condensation or resublimation of the tars. As a result, downstream process units are severely impaired in their function. To make the flammable gases usable for the application, therefore, a substantial elimination of the disturbing tars is required or it is the generation of a tar-free Nutzgases or lean gas required. For the resulting necessity of tar removal, there are different process approaches in the prior art that can realize differently good, but overall, insufficient gas qualities. In addition, some solutions also involve the high costs of investment and / or operation, which make the overall process economically unattractive. In gas production in a fixed bed or in a moving bed, in which coarse biomass under the influence of gravity in the mass flow successively durchwan changed a gasification pit from top to bottom, while slowly gassing, two main principles are distinguished:

• • Although countercurrent gasification is comparatively technically simple and undemanding, it produces flammable useful gases with extremely high tar contents.
• • Even with the more technically demanding DC gasification, it is only possible to produce flammable useful gases of sufficiently good quality or sufficiently low-flammable useful gases in very small units. Even with systems with an electrical power of about> 50 kW, however, it is becoming increasingly difficult to move the fuel bed in a uniform flow, so that in larger systems here too tars are found in too high a concentration in the product gas.

Also constructive variations of the two basic types described solve this Tar problem unconvincing, so that a downstream tar treatment stage, for example a gas wash or the use of catalysts, is indispensable if one tar-free lean gas should be generated. The catalytic tar removal However, this has the disadvantage that it is either insufficient, about the quality requirements to meet the combustible fuel gas, or that a considerable effort in terms of investment and Operating costs required. Also the tar removal from the combustible Nutzgas by gas scrubbing is not practical because of the high capital and operating costs, about that In addition, there is a disadvantage of gas scrubbing even in the worse ones energetic utilization of the biomass used, since the calorific value the deposited hydrocarbons is lost.

Biomass gasification is the concern of various companies and institutions. For example, the Fraunhofer Institute for Environmental, Safety and Energy Technology, UMSICHT, operates a 0.5 MW fluidized bed pilot plant, which is operated with a catalyst for cracking the tar. There are patents for gas purification by means of the catalysts ( DE 100 37 762 and EP 11 42 981 ). However, as already mentioned, the use of catalysts represents a considerable cost factor and is also problematic because the catalysts have to be regenerated and are often not tested in long-term tests.

One Another biomass gasification process is the CARBO-V of the company Choren. It produces a raw gas that has undergone gas scrubbing prior to further use must become. This method is expensive in terms of apparatus and thus susceptible, as it comes from an upstream low-temperature and the CARBO-V carburetor consists.

Furthermore, there is a system for gradual reforming, with metal balls as Wärmeträ germedium is operated. So far it has been in the form of a 1 MW pilot plant. In addition, there are other techniques with heat transfer media.

at Another method is the carburetor an evaporation and Pyrolysis stage upstream. Also this method and other methods or systems, for example, at the universities of Stuttgart, Karlsruhe, Siegen, at the TU Freiberg, Graz and Vienna as well as at the University of Applied Sciences Offenburg however are confronted with tar in the syngas and therefore require a gas wash and / or a catalyst.

• • Das Schwelgas bzw. das erzeugte Schwachgas ist erst nach einem Katalysatoreinsatz und/oder einer Gaswäsche in einem Verbrennungsmotor oder in einer Brennstoffzelle nutzbar. Ohne Katalysatoreinsatz und/oder Gaswäsche ist der Teergehalt des Schwelgases zu hoch.
• • Die bisherigen Anlagen weisen eine vergleichsweise aufwendige und somit anfällige Technik auf, vor allen Dingen werden im heißen Bereich der abrasiven Holzkohle bewegliche Teile und Armaturen eingesetzt.
• • Die Anlagen sind erst ab einer bestimmten Größe wirtschaftlich und somit nicht dezentral einsetzbar.

In summary, the disadvantages of the existing systems are the following:

• The carbonization gas or the weak gas produced can only be used after a catalyst insert and / or a gas scrubber in an internal combustion engine or in a fuel cell. Without catalyst and / or gas scrubbing the tar content of the carbonization is too high.
• • The previous systems have a relatively complex and therefore vulnerable technology, especially in the hot area of abrasive charcoal moving parts and fittings are used.
• • The systems are only economical above a certain size and therefore can not be used decentrally.

Further Procedures deal with a special carbonization gas flow guide but not the technique used in this invention be a side channel under the fixed bed grate to achieve a longer Residence time of the lean gas and the recirculation of carbonization gas, in the hot Gasification zone with the addition of steam to eliminate hydrocarbons used. Another method deals with pyrolysis gas recirculation, by suction in a tube with fan carried out in the biomass fixed bed to the pyrolysis reaction to catalyze. Subsequently a gasification takes place. Another method deals with a glowing Kohlebett, through which the carbonization gas after gasification, at the only Ash as a solid residue remains, to crack higher Hydrocarbons or tars is performed.

Other methods are concerned with the graded gasification with a deviating from the present invention construction: The Patent DE 101 51 054 describes a fast pyrolysis followed by an entrainment gasification. Another method deals with pyrolysis followed by combustion. Another method deals with a multi-zone gasification, which is preceded by a combustion. Other methods involve fractional or partial gasification followed by gasification and pyrolysis followed by fluidized bed gasification and tar cracking. Another method deals with a stepped gasification with two parallel fluidized beds. Other methods deal with a carburetor within a burner. The patent EP 0 979 857 A2 describes a two-stage fluidized bed or a corresponding fixed bed, which follows a fluidized bed or the. Another method uses the pyrolysis in the form of a jacket heating for an internal gasification. Other methods use pyrolysis, followed by cyclonic gasification followed by a cyclone as the second gasification stage, and separate gasification and cracking reactors connected via a tube into which oxygen is injected.

Further Procedures operate on the basis of a local allothermal temperature increase of the present Invention similar Idea, in which, however, the Schwelgasweg remains unchanged: Autothermal steam formation and adding the vapor to the gasification zone. Furthermore There is a method that autothermal steam drying and Steam gasification in a fixed bed for moist substances to be gasified, but which does not contain any special carbon monoxide.

The object of the present invention is to provide a gasifier and a gasification process which makes it possible, with a simple, robust and cost-effective technique from biomass, to use a tar-free, ie at most 50 mg, tar / Nm ^3- containing H ₂ - and to produce CO-rich carbonization gas which does not have to be aftertreated with a catalyst or with gas scrubbing.

These Task is by the carburetor according to claim 1 and a Gasification process according to claim 31 solved. Advantageous developments of the carburetor according to the invention and of the gasification process according to the invention are in the respective dependent claims described.

A gasifier according to the invention, in particular for the gasification of biomass, has the following constituents: a drying and pyrolysis zone for drying and pyrolysis of the biomass or of the raw material (the term zone and the term unit used in parallel here and hereinafter are defined spatially Understood region or component of the gasifier, which usually consists of several individual components), a below the drying and pyrolysis zone arranged reduction zone for catalytic fixed bed cracking and carbon conversion in the raw material and one below the reduction zone arranged Nachvergasungszone for re-gasification of carbon still contained in the raw material or for oxidation and reduction of the raw material. The device according to the invention is characterized in that it has a Pyrolyseschwelgasabführeinrichtung (for example, several channels), which serves the removal of carbonization resulting from the pyrolysis of the raw material that it has a discharge device (for example, a channel) for removal of carbonization produced in the Nachvergasungszone in that it has a mixing device connected to the pyrolysis gas discharge device and the discharge device for mixing the carbonization gases discharged from the drying and pyrolysis zone and the carbonization gases removed from the gasification zone, and that it has a carbonization feed unit (for example a bifurcated channel) corresponding to the line in the blender mixes smolder gases into the reduction zone. The pyrolysis unit may in this case be designed, for example, as a fixed bed gasification stage or as a fluidized bed gasification stage, ie the pyrolysis may be carried out either with the aid of a fluidized bed or with the aid of a fixed bed.

In A first advantageous embodiment of the biomass gasifier in the mixing device, a partial combustion unit, for example in the form of a carbon monoxide burner, at least in part Combustion of the exhaust gases discharged from the gasification zone serves.

The Mixing device of the carburetor advantageously has a feed unit (For example, a channel) for the supply of air and / or oxygen and / or recirculated flue gas and / or water vapor and it advantageously has a carbon monoxide monitoring device and / or an oxygen monitoring device to exclude of deflagration. The mixing device can advantageously a heat transfer unit exhibit, with the heat from the partial combustion is recuperative deductible.

At the partial combustion unit or to the Zuführein unit is advantageously a control device connected to control the amount supplied in air, oxygen, recirculated flue gas or steam. The control can advantageously by means of a temperature measuring point due to the temperature in the mixing device and / or the reduction zone respectively. So that in the event of a leak no carbonization leak, is the biomass gasifier advantageously at the end of the process chain or after the Schwelgasabzugseinheit or a filter, a suction or blower downstream, which or which generates a negative pressure. alternative For this purpose, a gas engine can be used for this purpose.

Of the Carburetor has an upper one below the drying and pyrolysis zone Packed bed zone and above the post-gasification zone, a lower packed bed zone on, in each case a Sperrschüttschicht for the carbonization from the raw material can be trained. Particularly advantageous in this case are the in The mixing device blended carbonization by means of Schwelgaszuleitungseinheit both Packed bed zones fed. The smoldering gases can in this case a lower region of the upper packed bed zone and an upper Area of the lower packed bed zone supplied be. In operation, the carburetor then preferably in the upper area the upper packed bed zone a barrier layer for the Smoldering gases from the raw material and in the lower part of the upper packed bed zone a loose layer from the raw material, as well as in the upper area of the lower packed bed zone a loose layer from the raw material and at the bottom of the lower packed bed zone a Sperrschüttschicht for the carbonization from the raw material. Here is preferably the height of the Sperrschüttschicht in the upper area of the upper packed bed zone greater than the height the bulk layer in the lower part of the upper packed bed zone and the height of the bulk pile layer greater than in the lower part of the lower packed bed zone the height the bulk layer in the upper part of the lower packed bed zone.

advantageously, has at least one of the packed bed zones a packed bed forming device to form the Sperrschüttschichten. Serve preferably swivel grates and / or pendulum grates.

Advantageously, the carburetor moreover also has a carbonization gas extraction unit, which serves to remove the tarry carbonization gases produced in the gasifier. Advantageously, the low-tarry gasses produced are discharged from the reduction zone above a barrier layer in the lower packed zone and below a barrier layer in the upper packed zone. In a further advantageous embodiment of the biomass gasifier according to the invention, the carbonization gas extraction unit has a discharge device (for example a channel) for discharging the cracked carbonization gas reacted with carbon from the reduction unit. The carbonization gas extraction unit is advantageously equipped with a gas dedusting device. Advantageously, this gas dedusting apparatus is furthermore provided with a return device for returning dust to the gasification unit and / or with a cooling scrubber for removing ammonia from the carbonization gas and / or with an ammonia recycling device Return of the removed ammonia equipped in the biomass gasifier. The gas dedusting device is advantageously designed as a cyclone. Before geous enough, the Schwelgasabzugseinheit on a consumption device, such as a motor or a combustion chamber, and / or a feeder (for example, a channel) for supplying catalytically cracked carbonization to one or this consumption device.

The Mixing device advantageously has a cracking unit, in which thermal cracking of the mixed carbonization gases can take place and the beyond to lead the cracked carbonization to Schwelgaszuleitungseinheit serves.

In a further advantageous embodiment, the carburetor an oxidant supply unit on which to the feeder an oxidizing agent, for example air or oxygen, to the post-gasification zone serves.

In In a further advantageous embodiment, the drying and pyrolysis zone a feeder (for example, a channel) for supplying a pyrolysis medium, This can be, for example, air, oxygen or recirculated flue gas be on. The drying and pyrolysis zone points beyond preferably a packed bed forming device (For example, a swivel or pendulum) to form a loose layer from the raw material.

In a further advantageous embodiment, the post-gasification zone a packed bed forming device for the formation of a loose layer from the raw material. The post-gasification zone preferably has the further an oxidant lumen for supplying an oxidizing agent to this loose layer and / or a residue disposal device. The bulk layer formation device is preferably designed as a swivel grid and / or pendulum grate. The residue disposal device preferably has a return device for the return of ash and / or inert material in the post-gasifying zone.

In a further advantageous embodiment, the Pyrolyseschwelgasabführeinrichtung at least one deduction unit (for example, a channel), with those incurred during drying and pyrolysis of the fuel Carbonization above and / or below the corresponding bulk layer withdrawn from the drying and pyrolysis zone and the mixing device supplied can be.

In According to a further advantageous embodiment, the carbonization gas supply unit has a plurality Supply lines (for example channels or bifurcated lines), which is the supply of carbonization preferably allow for any existing packed bed zone. The feed can be in one of the bulk layer zone trained bulk barrier layer or above or below this. The supply lines are advantageously equipped with annular gaps.

In a further advantageous embodiment, the fuel gas removal device the biomass gasifier a channel, with the carbonization from the gasification unit dissipated be a gas dedusting device for dedusting these discharged carbonization and another channel for supplying the dedusted carbonization as Fuel gases to the mixing device or the partial combustion unit on.

The discharged from the gasification zone Smoldering gases are preferred in the upper part of the post-gasification zone or dissipated above this. The gas dedusting device is advantageously a cyclone and advantageously comprises a return device for returning dust in the gasification unit.

The innovations of the biomass gasifier according to the invention or of the biomass gasification process according to the invention are in the cracking stage (also referred to as reduction unit or reduction zone) and the gasification stage (also referred to as the gasification unit or zone) of the gasifier and in a special partial combustion of carbonization gases in the partial combustion unit with air or oxygen and possibly low addition of steam. By this partial combustion of carbonization can autothermally increase the temperature of the carbonization. This allows at temperatures of about 800 ° C in the allothermal cracking stage or reduction unit auto-catalytic cracking of the pyrolysis coke, whereby a tar derer synthesis gas can be generated. The positive guidance of the carbonization gas necessary for this purpose is achieved by barrier layers, also referred to as barrier bulk layers, in which solids accumulate. These represent such a high pressure loss that the gas takes the way to the outside in the carbonization channels of the mixing device or in the partial combustion unit, where it passes to the partial combustion and is then fed back from there into the cracking stage. In addition, in the carbonization gas guide of the present invention, the pressure loss is minimized in the reaction zone below the barrier, where the partially burned carbonization stream is divided by appropriately routed channels prior to entry into the cracking stage and through both the top and bottom layers Partial layers ge is sent. The exit of the carbonization gas takes place in the middle of the cracking stage. Thus, within this stage, the cross-sectional area of the plant is charged twice.

• • Es kann ein teerarmes Synthesegas erzeugt werden, ohne dass ein Katalysator benötigt wird und ohne dass eine aufwendige Gaswäsche notwendig ist.
• • Bei der neuen Technik handelt es sich um eine technische einfache, aber trotzdem funktionelle und robuste Ausführung des Biomassevergasers, die eine kompakte Bauweise bei ausreichend großen Verweilzeiten des Kokses ermöglicht, womit der Biomassevergaser auch den unterschiedlich langen Reaktionszeiten in der Pyrolysestufe (nachfolgend auch als Pyrolyseeinheit bezeichnet) und der Crackstufe gerecht wird.
• • Das Cracken von höheren Kohlenwasserstoffen bzw. Teeren wird durch eine allotherme Crackstufe in dem insgesamt autothermen Prozess gewährleistet. Durch diese Betriebsart werden auch die sonst auftretenden lokalen Temperaturspitzen vermieden.
• • Für die spezielle Gasführung werden keine Armaturen benötigt.
• • Die üblicherweise hohen Druckverluste im Vergaser werden reduziert.
• • Vergasungsanlagen dieser Art sind auch im kleinen und mittleren Maßstab bis zu etwa 8 MW pro Einheit wirtschaftlich rentabel. Sie eignen sich daher für eine dezentrale Anwendung, besonders in Hybridsystemen (die bisherigen Anlagen sind darauf ausgerichtet, durch Erhöhung der Leistung „economies of scale" zu nutzen).

The biomass gasifier described above and the corresponding biomass gasification process have a number of significant advantages over the prior art:

• • Low-tar synthesis gas can be produced without the need for a catalyst and without the need for expensive gas scrubbing.
• • The new technology is a technically simple, but nevertheless functional and robust design of the biomass gasifier, which allows a compact design with sufficiently long coke residence times, whereby the biomass gasifier also the different lengths of reaction times in the pyrolysis (hereinafter referred to as pyrolysis designated) and the cracking level is fair.
• • The cracking of higher hydrocarbons or tars is ensured by an allothermal cracking step in the overall autothermal process. This mode also avoids the otherwise occurring local temperature peaks.
• • No fittings are required for the special gas routing.
• • The usually high pressure losses in the carburettor are reduced.
• Gasification plants of this kind are economically viable even on a small and medium scale up to about 8 MW per unit. They are therefore suitable for decentralized use, especially in hybrid systems (the previous systems are designed to use "economies of scale" by increasing performance).

One Biomass gasifier according to the invention can as described in the example illustrated below or used.

The only 1 shows a vertical biomass gasifier according to the invention, which consists of several components or zones (hereinafter also referred to as units usually). The constituents, which are identified by main reference numerals in the form of numbers such as "1" or "2", are usually divided into a plurality of subunits, which have the same main reference numerals as the associated unit in the following, but also with subordinate designation in addition are provided with letters (such as " 1a "or" 2c The biomass passes through the carburettor from top to bottom in accordance with gravity The first stage or uppermost zone or unit of the carburettor is the pyrolysis unit 1 that have a supply channel 1a for supplying air, oxygen and / or recirculated flue gas into a first raw material or biomass fixed bed 1d charcoal or pyrolysis coke. The formation of the fixed bed is done with the help of a around the fulcrum 1c pendulum pendulum grate 1b , Below the pyrolysis unit 1 There is a two packed bed zones 2e and 2f comprehensive reduction zone 2 , In the zones 2e and 2f In each case, a barrier layer in the form of a hot raw material fixed bed is formed. For simplified representation, reference numbers refer to below 2e and 2f not only the packed-bed zones, but also the associated barrier bulk layers formed therein. The formation of the Sperrschüttschichten takes place in that the pendulum grates 2a (Pivot point 2c ) and 2 B (Pivot point 2d ) are moved sufficiently slowly (a sufficiently fast movement of the pendulum grates leads, as for example with the fixed bed 1d to a rather loose composite of raw materials, so not to the formation of Sperrschüttschichten).

Below this reduction unit 2 is the post-gasification zone 3 , their raw material fixed bed 3b an oxidation zone 3g and overlying a reduction zone 3h having. This raw material fixed bed is also using a pendulum grate 3a (Pivot point 3y ) formed and held. At the top of the post gasification unit is a lumen 3i for collecting and removing carbonization gases as fuel gases, below is a lumen 3c (Oxygen excess zone) formed in the by means of a channel 3d if necessary preheated air is introduced. In the pyrolysis unit 1 Drying and autothermal pyrolysis of the biomass takes place, including in the allothermal cracking stage or the first and second barrier bulk layer 2e and 2f in each case catalytic cracking of the long-chain hydrocarbons or the reaction of the substances formed in the oxidation zone with the carbon (reduction zone). In the oxidation zone 3g the post gasification unit 3 the oxidizing agent reacts exothermically with the raw material (C + O ₂ → CO ₂ ), in the overlying reduction zone 3h The substances formed in the oxidation zone react with the carbon (essentially Boudouard reaction C + CO ₂ → 2CO). The gasification unit 3 also has a discharge channel 3e to remove ash and possibly inert material with an ignition loss <5%. This ash and / or the inert material is recovered by means of the return device 3f into the lumen 3i the post gasification unit 3 recycled. With the help of one below the pendulum grate 1b and the biomass fixed bed 1d and above the packed bed zone 2e , from the biomass gasifier leading channel 6a Pyrolyseswelwelgase be in an anteroom 5a the mixing device 5 guided. The mixing device 5 also has a carbon monoxide burner in a burner area 5c for the at least partial combustion of the fuel gases discharged from the gasification zone. The in the burner area opening channel 5d serves the controllable supply of oxygen, possibly also of preheated air or recirculated flue gas, possibly with the addition of water vapor. From the lumen 3i in the upper part of the gasification unit 3 leads a channel 8a for transporting the fuel gas into the dedusting device 8b , This has a channel at its upper end 8d for supplying the dedusted fuel gas in the carbon monoxide burner 5c on. At its lower end, the dedusting device has a return device 8c for returning dust to the gasification unit 3 or the lumen 3i on. Laterally next to the burner area or the inner tube 5c and below the anteroom 5a has the mixing device 5 a the inner tube 5c completely enclosing, cylindrical outer tube 5b for thermal cracking of the carbonization gas, which via a bifurcated channel 7 with two branches 7a and 7b in the upper or lower raw material fixed bed 2e respectively. 2f leads. The height of above the insertion of the channel 7a lying Sperrschüttschichtanteils the bulk layer 2e in this case is greater than the height of the lying below the insertion section bulk layer portion. The height of above the insertion of the channel 7b lying loose layer portion of the packed bed 2f is smaller than the height of the below the insertion range Sperrschüttschichtanteils. In the entry area to the raw material fixed bed are these two channel branches with annular gaps 7c and 7d fitted. With the help of on the left side of the carburetor with respect to the vertical between the two raw material fixed beds 2e and 2f from the biomass gasifier leading channel 4a the tarry low carbonization gas is discharged from the biomass gasifier. The Schwelgasabzugseinheit used for this purpose 4 points next to the canal 4a also a dedusting device 4d on, which at its lower end a Staubrückführvorrichtung 4b contains for returning the dust to be withdrawn gas taken in the lumen 3i the post gasification unit 3 , The dedusting device 4d has at its upper end a trigger channel 4c who becomes a consumer 4e (which in the present example is a gas engine) leads to.

The following paragraph describes the operation of the illustrated biomass gasifier. The charcoal or pyrolysis coke from the pyrolysis stage 1 traverses the carburetor by gravity from top to bottom. The pyrolysis stage or unit 1 be through the channel 1a supplied small amounts of possibly preheated air and / or recirculated flue gas. The pyrolysis stage 1 can be used variably in the form of an ascending or descending fixed-bed gasification or as a fluidized bed. The carbonization gas of the pyrolysis stage 1 is at the bottom of the pyrolysis stage through the channel 6a deducted. After a temperature increase of the pyrolysis gas by partial oxidation of the from the post-gasification zone 3 withdrawn carbonization, this proportion of gas is hereinafter referred to as fuel gas, by the carbon monoxide burner 5c tars are thermally cracked. For this purpose, air or oxygen or recirculated flue gas, possibly with the addition of a small amount of water vapor used. The supply happens here through the channel 5d wherein the supplied amount is controlled as described later. The carbonization gas with the remaining higher hydrocarbons then passes over the two channel branches 7a and 7b in two levels each over an annular gap 7c respectively. 7d in the area 2e respectively. 2f for fixed bed cracking and carbon conversion. This is done with the help of the Boudouard reaction C + CO ₂ → 2CO (Reduction of lumped, bound, ie "fixed" carbon).

The responsible amount of heat is exclusively with those in the mixing device 5 additionally heated carbonization gases from the first stage (the pyrolysis stage 1 ) or by partial combustion of the fuel gases of the last stage (the Nachvergasungseinheit 3 ) in the burner area 5c brought in. That in the area 5c or in the inner tube partially burned gas flows after combustion (which is shown in the drawing in ascending direction, see arrow) in the cracking unit 5b or the outer, descending through-flowed cylinder part (see arrow down) and heats that in the area 5a admixed gas from the pyrolysis stage 1 , Thus, a heat integration takes place by the hot gas from the burner area 5c Gas from the pyrolysis stage 1 is mixed and by the hot gas after cooling by the admixture on the "cold" side (area 5b ) flows and is warmed up even further. The fact that the carbonization gas in two levels in the cracker or the reduction unit 2 enters, then descending or ascending through the respective charcoal bed 2e respectively. 2f to the deduction or Schwelgasabzugseinheit 4 to move, is to be expected with a much lower pressure drop in the bed, as if the cross section of the apparatus would only take advantage of. The carbonization gas leaves the carburetor through the channel 4a after the cracking stage 2 to after a gas dedusting in the dedusting device 4d , in which larger particles are separated, further use in the gas engine 4e over the canal 4c to be fed. At the Schwelgas trigger or at the Schwelgasabzugseinheit 4 a pressure level is required, which ensures the directed Schwelgasbewegung by the apparatus. So that most of the carbonization from the pyrolysis stage 1 not directly through the top cracker fill 2e to the trigger, but the way on the outside temperature increase range 5 takes, is the lock bulk layer 2e made of charcoal.

The specific pressure drop in this barrier layer 2e is considerably larger than that in the outer Schwelgasbereich 5b , As the resulting absolute pressure drops across the bulk barrier layer 2e and over the Schwelgasbereich 5b are the same size, takes the largest portion of the pyrolysis gas the way through the outer tube 5b , Thus, a directional flow is possible without the use of expensive hot-run valves, such as sliders, in the field of abrasive charcoal. The absolute pressure loss over both bedding areas 2e such as 2f , in which cracking and Boudouard reaction take place, will also adjust in the same amount. In order to exclude bridge formations in the beds and for the defined fuel transport proven pendulum grates 2a and 2 B used to move the respective fixed bed. The unreacted charcoal forms the Sperrschüttschichten in the cracking area 2e respectively. 2f then to the post-gasification unit 3 or the corresponding stage for further implementation and complete oxidation. At this stage, a suitable return of dust ( 4b . 8c and 3f ) provided a very high proportion of ash / inert material in a fixed bed. This will be in the post-gasification stage 3 deliberately set a relatively small effective calorific value. In the bed 3g is from below over the canal 3d preheated air or oxygen as a gasification agent with a temperature greater than 320 ° C (the ignition temperature of charcoal) blown or supplied. The dispensers at the three feeders 1a . 3d and 5d are independently controllable. In the lowest part of the bed, the oxygen supply results in an area 3c and 3g with oxygen excess (λ> 1).

The carbon becomes in the oxidation region 3g burned to carbon dioxide, which then in the overlying reduction range 3h (λ <1, ie lack of oxygen) passes. As the carbon oxidation, which in the oxidation region 3g expires, is exothermic, is in the reduction range 3h reached a temperature level at which the Boudouard reaction proceeds again. In optimal conditions, this way in the field 3h almost as much carbon dioxide is converted to carbon monoxide, as previously burned in the lower range. This in the reduction zone 3h The resulting gas consists of nitrogen, carbon monoxide and the smallest possible amounts of carbon dioxide. Instead of the described fixed bed 3g and 3h can be analogously use a stationary fluidized bed. The fuel gas from N ₂ , CO and CO _{2 of} the last stage passes over the lumen 3i and the channel 8a to a dedusting device 8b and then to the partial combustion unit 5c or the particular carbon monoxide burner in which the carbon monoxide is partially combusted with preheated air. The over the channel 5d added amount of air is controlled by means of a downstream temperature measuring point (not shown). This detects the temperature in the mixing device 5 and / or in the reduction zone 3 , At the same time, a carbon monoxide monitoring device (not shown) ensures that reducing conditions prevail throughout the area. This way, deflagrations can be ruled out. Additional safety is provided as long as the temperatures are above the ignition temperature of carbon monoxide. The system is operated with a low negative pressure, so that in case of leakage no carbonization gases escape. After the burner, the temperature of the gas is so high that, after mixing the gas with the carbonization of the pyrolysis 1 gives a mixing temperature that allows thermal cracking. However, this temperature need not be so high that all tars are completely cracked. It only has to allow the cracking of most of the tars. The remaining higher-chain hydrocarbons are then in the downstream fixed bed 2e respectively. 2f autocatalytically cracked. Cracking thus takes place in two stages: first in the area 5b or the outer tube 5b thermally cracked, then in a fixed bed 2e respectively. 2f autocatalytically cracked.

Due to the resulting high pyrolysis gas temperatures or carbonization temperatures, sensible heat is introduced into the cracker, which is required there for cracking and simultaneous Boudouard reaction. Another heat supply provides the partial combustion in the burner 5c , They prevent the rapid hydrogen oxidation that occurs when air is added directly to the hot pyrolysis gas to increase the temperature by partial combustion. The use of the carbon monoxide burner 5c thus leads to a higher hydrogen content in the product gas. At the same time, since the water vapor content in the product gas decreases, a higher cold gas efficiency (defined as the chemical energy of the cold product gas relative to the chemical energy in the fuel) than that of the prior art (cold gas efficiency of currently about 80%) is to be expected. The expected hot gas efficiency of the gasifier (defined as the chemical and thermal energy of the hot product gas relative to the chemical energy in the fuel) is over 95% because its energy losses are essentially convective heat losses and radiation losses to the environment. Energy losses due to unburnt ash at the ash outlet are due to the formation of the oxidizing post-gasification zone 3g minimized.

Overall, the new gasification process can contribute to significant weaknesses correct the biomass gasification. Higher hydrocarbons are cracked, the carbon is fully reacted and the pressure drop in the gasifier is low. Impermissible temperature peaks in the area of the fixed bed cracker 2 are excluded by the allothermal operation of this stage and in the post-gasification stage 3 avoided by dilution of the residual carbon with ash / inert and / or water vapor and / or recirculated flue gas. The directional guidance of the carbonization streams is carried out without fittings by the use of Sperrschüttschichten 2e and 2f , Entrained ash particles in the pyrolysis gas of the first stage by a suitable design of the annular gaps 7c and 7d as well as (in relation to the channels 7a and 7b ) in appropriate places of the channels 8a and 6a arranged gas exhausts introduced together with the gas in the charcoal bed of the cracker and can not be so in the carbonization gas 5b accumulate. As the temperatures in the area of the carbon monoxide burner 5c may be above the ash softening point, this burner is 5c an effective hot gas dedusting in the form of a cyclone 8b upstream. The separated dust from this cyclone 8b and from the system downstream hot gas cyclone 4d will be in the post-gasification stage 3 led so that no carbon-rich ashes incurred as waste to be disposed of. When using unencumbered biomass, the ashes from the gasifier can be used as fertilizer, for example. However, the amounts of ash produced are usually very small, since the ash content of, for example, unloaded softwood is less than about 1 wt .-%. With the expected, almost complete cracking of the hydrocarbons fall in the low-temperature cooling for a gas engine no expensive to dispose tar fractions. In general, tar contents of a maximum of about 50 mg / Nm ³ in carbonization still within the engine 4e be incinerated. Ideally, the product gas from the novel carburettor must only be cooled, dedusted and freed from any ammonia that may be present in small amounts. The ammonia can easily be removed from the carbonization gas by means of a scrubber (not shown) and, after the solution has been driven out by heating the scrubbing water, can be returned to the gasifier in gaseous form, without ammonia concentrating in the system. The new process produces less condensate (water) in the carbonization cooling with significantly lower levels of organic compounds, thus simplifying environmentally sound treatment.

Claims (45)

Carburettor for the gasification of raw material, in particular of biomass, with a carburetor housing, which has arranged one another a drying and pyrolysis zone ( 1 ) for drying and pyrolysis of the raw material, a reduction zone ( 2 ) for catalytic cracking and carbon conversion of the raw material and a post-gasification zone ( 3 ) for after-gasification of carbon still contained in the raw material, wherein the gasifier a Pyrolyseschwelgasabführeinrichtung ( 6 ) for the removal of carbonization gases from the drying and pyrolysis zone ( 1 ), a fuel gas discharge device ( 8th ) for the removal of carbonization gases from the post-gasification zone ( 3 ), one with the Pyrolyseschwelgasabführeinrichtung ( 6 ) and the fuel gas discharge device ( 8th ) connected mixing device ( 5 ) for mixing the from the drying and pyrolysis zone ( 1 ) discharged carbonization gases and from the post-gasification zone ( 3 ) discharged carbonization gases and a carbonization gas supply unit ( 7 ) for conducting the in the mixing device ( 5 ) smoldering gases mixed in the reduction zone ( 2 ), characterized in that below the drying and pyrolysis zone ( 1 ) in an upper packed bed zone ( 2e ) and above the post-gasification zone ( 3 ) in a lower packed bed zone ( 2f ) In each case a Sperrschüttschicht for the carbonization gases from the raw material can be formed. Carburetor according to the preceding claim, characterized in that in the mixing device ( 5 ) smoldering gases mixed by means of Schwelgaszuleitungseinheit ( 7 ) two packed bed zones ( 2e . 2f ) can be supplied. Carburettor according to one of claims 1 or 2, characterized in that the carbonization gases by means of Schwelgaszuleitungseinheit ( 7 ) a lower portion of the upper packed bed zone ( 2e ) and an upper region of the lower packed bed zone ( 2f ) can be supplied. Carburettor according to the preceding claim, characterized in that the upper region of the packed bed zone ( 2e ) has a Sperrschüttschicht for the carbonization gases from the raw material and that the lower portion of the packed bed zone ( 2e ) has a bulk layer of the raw material, and that the upper region of the packed bed zone ( 2f ) has a bulk layer of the raw material and that the lower region of the bulk layer zone ( 2f ) has a Sperrschüttschicht for the carbonization gases from the raw material. Carburettor according to the preceding claim, characterized in that the height of the barrier bulk layer in the upper region of the packed bed zone ( 2e ) is greater than the height of the bulk layer in the lower region of the packed bed zone ( 2e ) and that the height of the barrier layer at the bottom of the packed bed zone ( 2f ) is larger as the height of the bulk layer in the upper region of the packed bed zone ( 2f ). Carburettor according to one of the preceding claims, characterized in that at least one of the packed bed zones ( 2e . 2f ) a packed bed forming device ( 2a . 2 B ) having. Carburettor according to the preceding claim, characterized in that at least one of the bulk layer forming devices ( 2a . 2 B ) has a grate, preferably a pivoting grid and / or a pendulum grate. Carburettor according to one of the preceding claims, characterized in that the mixing device ( 5 ) a partial combustion unit ( 5c ) for the combustion of the post-gasification zone ( 3 ) has discharged carbonization gases. Carburettor according to the preceding claim, characterized in that the partial combustion unit ( 5c ) has a carbon monoxide burner and / or a channel. Carburettor according to one of the preceding claims, characterized in that the mixing device ( 5 ) a feed unit ( 5d ) for supplying air and / or oxygen and / or recirculated flue gas and / or water vapor. Carburettor according to the preceding claim and according to one of claims 8 or 9, characterized in that the feed unit ( 5d ) into the partial combustion unit ( 5c ) and / or that the feed unit ( 5d ) has a channel. Carburettor according to one of claims 10 or 11, characterized in that the feed unit ( 5d ) has a control device and / or a temperature measuring point for controlling and / or controlling the supplied with it amount of air and / or oxygen and / or recirculated flue gas and / or water vapor. Carburettor according to one of the preceding claims, characterized in that the carburetor at least one carbonization gas extraction unit ( 4 ) for the removal of carbonization gases generated in the gasifier. Carburetor according to the preceding claim, characterized in that at least one of the carbonization gas extraction units ( 4 ) is arranged so that with it smoldering gases below the upper packed bed zone ( 2e ) and above the lower packed bed zone ( 2f ) are deductible. Carburettor according to one of claims 13 or 14, characterized in that at least one of the carbonization gas extraction units ( 4 ) a discharge device ( 4a ) for the removal of catalytically cracked carbonization gases from the reduction zone ( 2 ) and / or a gas dedusting device ( 4d ) and / or a delivery device ( 4c ) for supplying catalytically cracked carbonization gases to a consumption device ( 4e ) and / or a return device ( 4b ) for the return of dust to the post-gasification zone ( 3 ) and / or a cooling scrubber and / or an ammonia recycling device for the return of ammonia preferably in gaseous form in the gasifier. Carburettor according to the preceding claim, characterized in that the gas dedusting device ( 4d ) has a cyclone and / or that the consumption device ( 4e ) has a motor or a combustion chamber and / or that the discharge device ( 4a ) and / or the feeding device ( 4c ) is a channel. Carburettor according to one of the preceding claims, characterized in that the mixing device ( 5 ) a cracking unit ( 5b ) for the thermal cracking of carbonization gases and / or for the supply of cracked carbonization gases to the carbonization gas feed unit ( 7 ) and / or an anteroom ( 5a ) and / or a carbon monoxide monitoring device. Carburettor according to the preceding claim, characterized in that the cracking unit ( 5b ) has at least one pipe or a channel and / or that the negative pressure generating device comprises a suction and / or a fan and / or a gas engine. Carburettor according to one of the preceding claims, characterized in that the carburetor comprises an oxidant supply unit ( 3d ) for guiding an oxidizing agent to the post-gasification zone ( 3 ) and / or that the oxidizing agent contains air and / or oxygen or consists thereof. Carburettor according to one of the preceding claims, characterized in that the drying and pyrolysis zone ( 1 ) has a fixed bed gasification stage or a fluidized bed gasification stage. Carburettor according to one of the preceding claims, characterized in that the drying and pyrolysis zone ( 1 ) a feeder ( 1a ) for supplying a pyrolysis medium and / or a packed bed formation device ( 1b ) for forming a packed bed ( 1d ) from the raw material. Carburettor after the previous one claim, characterized in that the bulk layer formation device ( 1b ) has a grate, in particular a swiveling grate and / or a pendulum grate, and / or that the pyrolysis medium contains or consists of air and / or oxygen and / or recirculated flue gas and / or that the feed device ( 1a ) is a channel. Carburettor according to one of the preceding claims, characterized in that the gasification zone ( 3 ) a packed bed forming device ( 3a ) for forming a packed bed ( 3b ) from the raw material and / or an oxidant lumen ( 3c ) for supplying an oxidizing agent to the packed bed ( 3b ) and / or a residue disposal device ( 3e ) having. Carburettor according to the preceding claim, characterized in that the bulk layer formation device ( 3a ) has a grate, in particular a swivel grate and / or a pendulum grate, and / or that the waste material disposal device ( 3e ) a return device ( 3f ) for the return of ash and / or inert material to the post-gasification zone ( 3 ) having. Carburettor according to one of the preceding claims, characterized in that the Pyrolyseschwelgasabführeinrichtung ( 6 ) at least one deduction unit ( 6a ) for the extraction of carbonization gases above and / or below the drying and pyrolysis zone ( 1 ) and for supplying these carbonization gases to the mixing device ( 5 ) having. Carburettor according to the preceding claim, characterized in that at least one of the extraction units ( 6a ) is a channel. Carburettor according to one of the preceding claims, characterized in that the carbonization gas feed unit ( 7 ) at least two lines ( 7a and 7b ) and / or has a bifurcated line. Carburettor according to the preceding claim, characterized in that at least one of the lines ( 7a and 7b ) an annular gap ( 7c and 7d ) and / or that at least one of the lines ( 7a and 7b ) is a channel. Carburettor according to one of the preceding claims, characterized in that the fuel gas discharge device ( 8th ) a fuel gas supply device ( 8a ) for the supply of carbonization gases from the post-gasification zone ( 3 ) and / or a gas dedusting device ( 8b ) for the dedusting of carbonization gases used as fuel gas and / or a Brenngasabführvorrichtung ( 8d ) for the removal of carbonization gases and for the supply of these carbonization gases to the mixing device ( 5 ) having. Carburettor according to the preceding claim, characterized in that the gas dedusting device ( 8b ) a return device ( 8c ) for the return of dust to the post-gasification zone ( 3 ) and / or that the gas dedusting device ( 8b ) has a cyclone and / or that the fuel gas supply device ( 8a ) and / or the fuel gas removal device ( 8d ) is a channel. Gasification process for the gasification of a raw material, in particular biomass, in which the raw material in a drying and pyrolysis zone ( 1 ) is subjected to drying and pyrolysis, in which, in a zone below the drying and pyrolysis zone ( 1 ) arranged reduction zone ( 2 ) Tar are catalytically cracked and reacted with the raw material carbon, and in which in a below the reduction zone ( 2 ) arranged post-gasification zone ( 3 ) in which the raw material still contained carbon is post-gasified, wherein carbonization gases from the drying and pyrolysis zone ( 1 ) are discharged, with carbonization from the gasification zone ( 3 ) are removed, wherein the from the drying and pyrolysis zone ( 1 ) discharged carbonization gases with those from the gasification zone ( 3 ) are blended, and wherein the mixed carbonization gases then in the reduction zone ( 2 ), characterized in that in a below the drying and pyrolysis zone ( 1 ) arranged upper packed bed zone ( 2e ) is formed of a barrier bulk layer for the carbonization gases from the raw material and that the carbonization gases from the drying and pyrolysis zone ( 1 ) are removed by means of this barrier layer and that in a above the post-gasification zone ( 3 ) arranged lower packed bed zone ( 2f ) is formed a barrier bulk layer for the carbonization gases from the raw material and that the carbonization gases from the gasification zone ( 3 ) are removed by means of this barrier layer. Method according to the preceding claim, characterized in that a gasifier according to one of claims 1 to 30 is used. Method according to one of the two preceding claims, characterized in that the barrier bulk layer of the packed bed zone ( 2e ) in the upper region of the packed bed zone ( 2e ) is formed and that the carbonization gases are introduced below this barrier layer in a bulk layer of the raw material and that the bulk layer of the bulk layer zone ( 2f ) in the lower part of the packed bed zone ( 2f ) is formed and that the carbonization above this Sperrschütt layer are introduced into a packed layer of the raw material. Method according to one of claims 31 to 33, characterized in that the from the post-gasification zone ( 3 ) discharged carbonization gases are at least partially burned. Method according to the preceding claim, characterized characterized in that with the help of partial combustion carbonization temperatures above about 800 ° C be generated. Method according to the preceding claim, characterized in that the from the post-gasification zone ( 3 ) deducted carbonization gases are dedusted before their combustion. Method according to the preceding claim, characterized in that the dust in the post-gasification zone ( 3 ) is returned. Method according to one of claims 34 to 37, characterized that the carbonization gases to be burned air and / or oxygen and / or recirculated flue gas and / or steam is supplied. Method according to the preceding claim, characterized in that the amount of air and / or amount of oxygen and / or amount of flue gas and / or amount of steam fed to the carbonization gases to be combusted is determined on the basis of the temperature in the reduction zone ( 2 ) and / or based on the temperature in a zone in which the from the drying and pyrolysis zone ( 1 ) discharged carbonization gases with those from the gasification zone ( 3 ) are blended, and / or controlled by other parameters. Method according to one of claims 31 to 39, characterized in that carbonization gases from the reduction zone ( 2 ) are discharged. Method according to the preceding claim, characterized in that the carbonization gases above the lower packed bed zone ( 2f ) and below the upper packed bed zone ( 2e ) are discharged. Method according to one of claims 40 or 41, characterized that the payable Smoldering gases before removal Dedusted and / or subsequently supplied to a consumer and / or that from the effluent gases to be removed Ammonia is removed. Method according to the preceding claim, characterized in that the dust in the post-gasification zone ( 3 ) is returned. Process according to one of Claims 31 to 43, characterized in that the raw material in the drying and pyrolysis zone ( 1 ) Air and / or oxygen and / or recirculated flue gas is supplied. Method according to one of claims 31 to 44, characterized in that in the post-gasification zone ( 3 ) ashes and / or accumulating inert material at least partially into the post-gasification zone ( 3 ) is returned.