HK1148550B - Autothermic method for the continuous gasification of substances rich in carbon - Google Patents

Description

Autothermal process for the continuous gasification of high-carbon materials

Technical Field

The invention relates to an autothermal method for the continuous gasification of high-carbon substances in a vertical treatment chamber having a calcination region and an oxidation region, in which the high-carbon substances calcined are oxidized with an oxygen-containing gas, wherein gaseous reaction products are removed at the upper side of the vertical treatment chamber, which is designed in the form of a vertical kiln through which a cyclically guided bulk material, which is not oxidized per se, flows continuously from the top downwards, into which the high-carbon substances are added before entering the shaft kiln inlet.

Background

Such processes have long been known and are used, for example, in convection gasifiers. In these processes, the carbon product or also a biomass moving toward the bottom of the gasifier is passed around by the countercurrent flow of the process gas produced. The process gas produced can be burnt directly or used for synthesis. The disadvantages of this method described above are: the method can naturally be carried out self-heating by the high-carbon substance supplied, but the process gas depends to a large extent on the high-carbon substance supplied, so that it is accordingly difficult to control the method. This method is completely unsuitable for the treatment of contaminated high-carbon substances, such as plastics containing fluorine and chlorine, contaminated waste, pharmaceuticals, etc.

It is known to use waste in electric low shaft furnaces, where the production of calcium carbide, ferrosilicon, ferrochrome, etc. is energetically favorable at very high temperatures. Such a method does not of course work self-heating, but rather requires the use of hollow electrodes which are self-igniting or self-sintering to deliver a considerable energy source to generate the required high temperatures. Such a process is described, for example, in DE 102006023259A 1, which is directly connected to the production of the abovementioned substances.

The method described at the outset can in principle also be used for coal gasification, wherein the provision of a calcination zone can generally be dispensed with when coal is used.

Basically, other thermal methods are also known for gasifying high-carbon substances, which require an external energy supply, as described in the aforementioned patent documents. In order to carry out the autothermal gasification process, it is often necessary to use a fluidized-bed reactor, as disclosed, for example, in DE 3635215. The disadvantages are that: in order to keep the fluidized bed stable, it is technically complicated to generate the secondary energy required independently of the process, and it is also difficult to grasp the specific physical requirements for the substances used, such as density, transport conditions, dust emission conditions and particle size. It is known that when using the autothermal process, a rotary drum reactor can also be used, as described in DE 2844741. Since the residence time of the reaction gases in the rotary drum reactor is short, the optimum gas balance cannot be set, so that a large amount of low-value gas is produced.

In principle, autothermal gasification processes are advantageous which provide gases rich in carbon monoxide, the hydrogen content of which can be determined and adjusted by the hydrogen content of the carbon support used and, if appropriate, by the addition of water to the gasification process. Wherein the thermal energy required for the gasification can be obtained from the partial oxidation of the raw materials used.

Even if an autothermal gasification process is used, it is also possible to use a fluidized-bed reactor, as described, for example, in DE 4427860. In this patent, it is sought to make the carbon support as thin as possible and to subject it to oxidation in the gas phase in order to convert it completely to carbon monoxide in a short residence time. For this purpose, a very elaborate comminution treatment of the carbon support is required, wherein it is not possible to use plastic-containing streams, since these have a tendency to stick or form droplets in the gas phase.

The use of the rotary drum reactor process in the autothermal gasification process is difficult due to the short residence time of the gas and requires a complex reactor structure as described in DE 3216836C 2.

Plants for the autothermal coal gasification are disclosed, for example, in DE 3241169C 2, but the use of waste products containing, for example, plastics is generally not permitted. In order to be able to fulfill the latter requirement, different approaches are proposed, for example, from DE 19609721 and DE 4326484, but this also leads to a number of problems: problems in the supply of plastics to the reactor, problems with the displacement of the reactor due to welding, residues which cannot be gasified, deposits of oil and tar in the gas which has been produced, long cleaning down times, formation of dioxides and furans, and corrosion due to chlorine or hydrogen chloride.

Gasification of organic materials in multiple stages in successively connected reactors, as disclosed, for example, in DE 19945771C 1 or DE 19755693C 1, uses a heat carrier medium. Such a multistage gasification process requires a complex heat exchange system, and the process-related exhaust gas emissions limit the use of material qualities for heavy metal content and for other emission-related harmful substances. Finally, it is known that carbonaceous materials are gasified in a fixed bed reactor for subsequent regasification at high pressure in a flue flow reactor. In this way, it is also possible to treat chlorine-containing flue streams, for example flue streams containing high PVC components (polyvinyl chloride components), and carbon carriers containing high pollutant components, such as heavy metals or other harmful substances. Such gasification processes are described, for example, in DE 10031501 a1, and have the disadvantage of a very complex pretreatment of the material, which is described separately, for example, in DE 10142290 a 1. A high degree of technical complexity is also demonstrated, for example, by specific solutions which relate to the supply of material, prevent fluctuations in the raw gas (see also DE 102004001708 a1) or avoid deposits in the raw gas region (see, for example, DE 10330512 a 1).

To achieve neutralization of the hydrogen chloride. In the past, a complex quench system was generally required, for which reference was made to DE 4309493C 2 in order to avoid corrosive damage to the plant.

The method mentioned AT the outset is disclosed in AT 387786B. In this patent, an inert bulk material is guided cyclically through a shaft furnace. The material is deliberately conducted back at a high temperature in order to be able to be dried in a separate drying device. The high residual heat of the bulk material taken out of the shaft kiln does not allow the use of certain substances with a high carbon content, such as certain plastics, since these substances bind the bulk material before it is introduced into the kiln, thus interrupting the bulk material flow. There is also the possibility of uncontrolled pre-reactions and corresponding formation of harmful substances. This method is carried out in a plurality of spatially separated regions, so that corresponding transport devices are required for transporting the bulk material, and it is difficult to control the gaseous by-products.

Disclosure of Invention

The object of the invention is to improve a method of the type mentioned at the outset in such a way that it is not sensitive to reactions using high-carbon substances of different quality without a significant increase in costs.

According to the invention, the above object is achieved by the initially mentioned continuous process in which the oxygen-containing gas is introduced at least partially below the oxidation zone, thereby causing an ascending gas flow, wherein the bulk material and the ash product are cooled in the waste heat zone to a temperature of up to 450 ℃ by the ascending gas below the oxidation zone, and furthermore the oxygen-containing gas is introduced at least partially at the lower end of the shaft furnace and the bulk material is cooled in counterflow in a recooling zone located below the waste heat zone to a characteristic temperature (eignemperatur) of less than 100 ℃ before being removed from the shaft furnace for energy recovery.

The fact has proved that: by mixing the carbonaceous material with a substantially inert bulk material and by conducting the mixture of bulk material and carbonaceous material in a shaft furnace in the presence of a counterflow rising gas, the material with a high carbon content can be gasified autothermally, in which case no special requirements are imposed on the quality of the carbonaceous material used. It is only necessary to note that: the amount of carbonaceous material supplied should be sufficient to maintain a strict auto-thermal equilibrium in the shaft furnace. The fact has proved that: high carbon substances with side lengths of up to 40cm can be added without interfering with the process.

Of particular interest for the process is a bulk material which, on the one hand, has the function of a heat carrier medium and, on the other hand, also serves as a transport medium which conveys the high-carbon material to the oxidation zone for its final gasification and then conveys the gasification residue as ash to the outlet at the lower end of the shaft kiln. Another important thing is: a bulk material is gas-permeable and can therefore be passed through by an ascending gas stream, so that a heat exchange between the bulk material as heat carrier medium and the ascending gas stream can be achieved in the individual reaction zones.

For the purpose of energy recovery and cooling of the bulk material and ash below the oxidation zone, the bulk material stream is cooled in a waste heat zone to a characteristic temperature of approximately 450 ℃ by direct cooling with an oxygen-containing gas, wherein for the case of water supply for the process it is preferably carried out in the region of the waste heat zone, in which the water vapor produced rises and participates in the synthesis gas reaction in the region of the oxidation zone.

In order to improve the energy balance and to simplify the handling of the bulk material which has to be removed in the lower region of the shaft furnace, the oxygen-containing gas is at least partially fed in the lower end of the shaft furnace, so that the bulk material is cooled in a counterflow manner in a recooling zone below the residual heat zone to a specific temperature below 100 ℃ before being removed from the shaft furnace. In this way, it is entirely possible to feed temperature-sensitive plastics, bitumen, oil-contaminated soil, cellulosic chips (shredderlichhtflight) etc. to the bulk material before it is re-introduced into the shaft kiln without said substances reacting uncontrollably or hindering the bulk material flow by adhesion.

Finally, the purely mechanical properties of the bulk material also play a role, the particle size thereof preferably being not more than 20cm, in particular preferably in the range from 1 to 8 cm. The particle size of the bulk material is also prevented by mechanical shearing from sticking together with the plastic-containing material, so that complete gasification of all the supplied carbon-containing material in the oxidation zone is possible.

As the bulk, a mineral material, a ceramic material or a metallic material having the above-mentioned particle size may be used at least partially, and/or a calcined product of mineral nature such as CaO is used, but a precursor of the calcined product such as limestone may also be used. CaO has the advantage that it is also suitable for combining the halogens contained in the material stream, which react with calcium and appear as harmless chlorides or fluorides. For this purpose, it is particularly advantageous to design a portion of the bulk material as fines having a particle size of less than 2mm, wherein these fine particles can rise at least partially with the gas flow and can be filtered off at the upper side of the shaft furnace if necessary. The dust produced can also be completely or partially returned to the bulk material circuit. In the case of limestone as bulk material, the temperature in the oxidation zone is preferably adjusted so low that complete roasting of the limestone does not take place, but only a thin CaO layer is formed on the original limestone, thereby retaining its ability to combine with halogen without generating a large amount of CaO. Limestone itself has a higher mechanical load-bearing capacity than CaO.

Heavy metals that may enter the process as contaminants in the feed stream may generally remain in the bulk material recycle, but part of the stream may be extracted or eliminated from the process as the filter dust accumulates in significant quantities.

The ability to use CaO (even as a thin layer on limestone) in combination with halogens and the ability to controllably use the material to separate heavy metals also allows the design of a specific method for the disposal of waste materials related to plastics such as PVC, also contaminated wood, asphalt, oil-contaminated soil, flakes, fiber debris as a residue of automotive recycling, etc.

Depending on the type of high-carbon substance used, according to a further development of the process, the bulk material flow can be first dried in a drying zone while being heated to a characteristic temperature of from 20 ℃ to 100 ℃ by means of countercurrent ascending gas above the calcination zone and then, until the calcination zone is reached, pre-degassed in a pre-degassing zone while being further heated to a characteristic temperature of from 100 ℃ to 450 ℃.

As mentioned, the rising gas flow provides the energy required for drying and pre-degassing, and the counter-current gas flow is cooled to a lower temperature before being removed at the upper side of the shaft furnace.

In the region of the calcination zone, the material flow consisting of bulk material and high-carbon material is subsequently heated to a characteristic temperature of 1200 ℃.

Depending on the high carbon species supplied and the desired composition of the gaseous reaction products, water may also be intentionally added directly to the oxidation zone.

In a particularly preferred embodiment of the invention, the gas produced is reprocessed in a flue gas flow (Flugstrom) regasification zone with steam after it has been removed on the upper side of the shaft furnace.

The gas withdrawn is a gas mixture comprising the gases (at least CO and H) produced in the oxidation zone₂) And gas from the pre-deaeration zone, wherein the gas is other than gaseousThere may be soot mixed with the gas in addition to the hydrocarbons. In the case of air as oxidizing gas, the gas produced also contains a corresponding nitrogen component. This soot is caused by the fact that decomposition of the hydrocarbons already takes place in the pre-deaeration zone at a comparatively low temperature, but there is insufficient temperature and residence time for complete decomposition into the desired reaction gases CO, H₂And a chain length of less than C₄The hydrocarbon of (2). By means of the flue gas stream regasifier, the long-chain hydrocarbons still present can then be decomposed, so that the desired CO, H is subsequently produced₂And a chain length of less than C₄As the final product of the process. Such synthesis gas may have many known uses. For example, for combustion in a combustion chamber, wherein the hot gases produced can be used for the driving of a hot gas turbine and/or a steam turbine for the generation of electricity; and/or water vapor may be used as a heating medium during the heat treatment. This synthesis gas can be purified by filtration and/or gas cooling and used as heating gas in a thermal treatment process, for example for combustion in a combustion shaft furnace and/or for power generation in a gas engine. One great advantage here is that: the synthesis gas can also be obtained from biomass, so that, for example, in the lime production process, the CO can be significantly improved₂Equilibrium, and in these processes so far only limited to the use of organisms with certain properties.

The cleaned synthesis gas is also suitable for being decomposed into its components by partial liquefaction, wherein the pure components contained in the synthesis gas can also be obtained by using a pressure-shift-adsorption process. Finally, the cleaned synthesis gas or one of its components can also be used wholly or partly as a basic product or intermediate product of the synthesis chemistry, independently of what raw material is initially supplied as carbonaceous material for the process.

In order to achieve the desired presence of water vapor in the flue stream-regasification zone, this can be achieved by adding water or water vapor or by water vapor escaping in the drying zone.

The process can be carried out without problems under pressure conditions close to ambient pressure, with a pressure range in the range from-200 mbar to 1000mbar (lu) having proven particularly suitable. Particularly advantageous is the following: within the scope of the method, a negative pressure is generated in the shaft kiln, which negative pressure prevents: gaseous end products or intermediate products can also escape from the shaft furnace without a strict seal, for example in the region of the supply lines or the regulating devices. This underpressure can be established, for example, by a suction device which can also be used for sucking off gaseous reaction products.

Preferably, all process zones are arranged in a single chamber from drying to recooling, so that no transport devices have to be arranged between the zones. For the material supply, a water-cooled gravity chute, which is arranged on the upper side of the shaft kiln and has no fittings and moving parts, is preferably used. Additional discharge points, such as may otherwise be required for conditioning the material in the process as bulk material, reactants or involved materials, can be omitted.

In order to avoid the formation of carbides in the oxidation stage in the case of CaO as bulk material, a temperature control of the process has proven to be advantageous, in this region the temperature is controlled to below 1800 ℃.

Oxygen-containing gases and/or fuels are preferably supplied to the oxidation zone. This can be performed at the time of ignition, i.e. at the time of start-up of the method, but it can also be performed for the purpose of controlling the position, size and temperature of the various zones in the shaft furnace. This prevents the following phenomena from occurring: the individual zones are shifted; the temperature levels used in the process reach unfavourable values; or the edge regions are overheated and thus dissipated, interrupting the process. In an ideal situation the fuel supply is not necessary.

Drawings

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The attached drawings show that:

FIG. 1 is a schematic view of a shaft kiln for gasifying high carbon materials;

FIG. 2 is a schematic view of the vertical kiln shown in FIG. 1, with downstream utilization of process gas.

Detailed Description

Fig. 1 shows a schematic illustration of a shaft kiln 100 which, in terms of its construction, essentially corresponds to a calcining shaft kiln, as is used in the sintering process in large-scale technology. The shaft kiln is used as a gasification reactor in carrying out the present invention. For this purpose, the shaft furnace 100 is continuously supplied with a mixture of a high-carbon substance and a refractory bulk material. The operation of the gasification reactor is adjusted in such a way that the process is carried out in a self-heating and smooth manner by oxidation of the high-carbon substances used, which can be supported by a dead-space burner 5, 6, 7, in particular for the start-up of the process.

In the exemplary embodiment shown, the shaft kiln or gasification reactor 100 is controlled in such a way that the gasification takes place in seven different process zones. After passing through a bulk material column 1 into the shaft kiln 100, the high-carbon material mixed with the bulk material is first passed into a drying zone a, in which it is dried at a characteristic temperature of 20 to 100 ℃. Subsequently, they enter a degassing zone B in which they are degassed by degassing at a characteristic temperature of from 100 to 500 ℃ to remove volatile constituents. The high-carbon material that has been deaerated is then fed, under the action of the downwardly moving bulk material, which also serves as a heat medium and transport medium, into a calcination zone C, in which heating is effected to a characteristic temperature of up to 1200 ℃, and the carbon still present is then gasified in a subsequent oxidation zone D by supplying oxygen-containing gas at a temperature of less than 1800 ℃. After leaving the oxidation zone, the refractory bulk material containing ash is cooled to approximately 450 ℃ in a waste heat zone E by direct cooling with oxygen-containing gas and/or optionally by water introduction with steam generation, wherein the oxygen-containing gas originally in a recooling zone F below the waste heat zone is heated as a counterflow to the bulk material and, on the other hand, the bulk material is cooled to below 100 ℃ by counterflow oxygen-containing gas introduced in the shaft kiln floor for the purpose of energy recovery. The inlet duct 8 for the oxygen-containing gas on the bottom of the shaft furnace 100 also represents the beginning of a gaseous counter-current which extends through all the process zones mentioned above.

As already mentioned, in this case in the aftercooling zone F and in the afterheat zone E following in the direction of gas movement, the oxygen-containing gas is first heated to above 450 ℃ before the oxidation of the carbides or of the carbon present in pure form takes place in the oxidation zone (with possible continued direct supply of oxygen-containing gas). The reaction gas rises further in correspondence with the temperature in the oxidation zone D and ensures the temperature level required there in the calcination zone C. The reaction gas then flows through the pre-degassing zone B and, with further cooling, through the drying zone A, the reaction gas emerging at the upper end of the bulk column as synthesis gas from the oxidation stage, CO and H₂Water vapour and carbon oxides (in particular from the pre-degassing stage B), which in an unfavourable case contain soot in addition to dust as a result of the decomposition process in the pre-degassing zone B. In order to increase the quality of the reaction gases, a post-flue-stream gasification zone G is therefore provided in the upper reactor section, in which gasification zone the dust-and soot-containing gas is thermally reprocessed with the addition of water vapor by supplying oxygen at a temperature of 500-1000 ℃ as raw synthesis gas of high quality for material and/or thermal applications.

By mixing the high-carbon material with the refractory bulk material, it has been shown that seven such zones are formed in the case of continuous passage through the vertical kiln 100, which enable gasification of a very wide range of different carbon supports under conditions of a suitable pressure range from-200 mbar to 1000 mbar. Only high-purity carbon carriers such as coke, coal, petroleum coke, anthracite or waste oil have hitherto been used for the gasification process, while the use of bulk materials as special heat carriers and transport carriers also permits the use of organic materials whose melting and softening points are in the range above 20 ℃ and below 500 ℃. Also belonging to this class are those carbon compounds having a polymeric structure, in which the new process allows to greatly reduce the formation of fission products of the oil-or tar-containing type by purposefully controlling the characteristic temperature of the material or of the fission products. By using an autothermal process of partial oxidation, no emissions source is generated, so that for example high carbon substances with a high heavy metal content (as is produced on painted wood) can also be used.

As mentioned, CaO is particularly suitable as a bulk material having a particle size of up to 20cm, wherein a particle size in the range of 1 to 8cm has proven particularly advantageous. Bulk materials having such particle sizes may not only be used as a thermal medium and a transport medium, but also may contribute, by their mechanical properties, to the absence of agglomeration or caking of the high carbon material during operation of the shaft kiln 100. The mechanical friction of the particles, which are often in motion relative to each other, ensures this.

There is another advantage in using CaO as bulk: it is useful as a reaction component for example for halogens and to some extent suppresses the formation of dioxides, furans etc. The formation of these toxic substances can also be suppressed by: there is no oxygen as a reactive component in the temperature range critical for the formation of these species. It is particularly advantageous here to add to the bulk material a fine-grained component having a grain size in the millimeter range and below, for example having a grain size in the range of approximately less than 2mm to micrometers. This fines have a large reaction surface and are partly present as dust in the reaction gas, which can easily be filtered out of the reaction gas.

In addition, the bulk material is taken out at the bottom of the shaft kiln 100 and returned to the shaft kiln 100 again by means of a circulation guide 13 while new high-carbon substance 14 is supplied. In this region, fine particles can also be filtered out, for example, by filtration.

In the gasification of polymers, in particular contaminated polymers, this has hitherto been a great problem, since particularly careful sealing of the fittings is required at high pressures; the method can advantageously be carried out with a slight underpressure, preferably in the range of up to-200 mbar, ideally not exceeding 1000mbar in the case of overpressure. Under the condition of negative pressure, the sealing purpose can be achieved by adopting the following modes: the charging of the reactor takes place via a bulk material column 1 which is loaded on the reactor packing (Sch ü ttung) due to the static dead weight and can thus be connected without further fittings to the reactor charging device 2. After the high-carbon material has been admixed to the bulk material as described, the bulk material is first conveyed to a bulk material receiver 3. Since the refractory bulk material is continuously removed at the reactor bottom 4, the bulk material is continuously passed through the reactor bottom. In this way, the mixture of refractory bulk material and high-carbon material automatically slides down from the bulk material receiver 3 into the reactor, for which no fittings or other process control devices are required. The height of the bulk column is chosen such that it ensures the sealing of the reactor gas phase from the atmosphere by its own pressure loss through the packing. In which the operation of the reactor under reduced pressure is particularly advantageous, since the escape of reaction gases is excluded.

The input of thermal energy takes place substantially in the oxidation zone D, wherein the basic power in question is achieved by the distribution of oxygen 5 and fuel 6, such as fuel oil, natural gas or purified synthesis gas according to the process, through the burner lances 7 as direct combustion devices, into the charge. The main energy input is achieved, however, by partial combustion of the previously calcined high-carbon substances in the bulk material and by supplying oxygen or also a single air through the reactor bottom 8. The task of the dead-space burner 7 is to ensure safe and reliable ignition of the reaction components in the oxidation zone D.

The hot gases produced, which are essentially all carbon monoxide but also contain hydrogen, flow upwardly from the oxidation zone D through the reactor charge zone and serve as energy carriers for heating the process zone designed above the oxidation zone D.

As already mentioned, in the drying zone a, the high-carbon material, which in practice contains mostly moisture, is heated to a characteristic temperature of up to 100 ℃ under the conditions of vaporization of the moisture contained; at the same time, thermal cracking of the polymeric and organic components is effected in the subsequent presteaming zone B. The increase in the characteristic temperature of the feedstock is limited to about 450 c, based on the energy required for fission. In this zone, the hot gases from the zones located below are mixed there with the gases resulting from the thermal cracking.

The oxidation in the oxidation zone D is controlled in such a way that it is ensured that the carbon which is still present and not gasified is completely oxidized to carbon monoxide. This control is carried out firstly by purposefully adjusting the flow rate via continuous removal of the bulk material on the reactor bottom 4, but can also be carried out if desired by adjusting the dead-load burner 7 or by varying the portion of the carbonaceous material in the bulk material receiver 3.

If it is desired to supply water, a water supply device 9 is preferably arranged in the region of the residual heat zone E, the water being converted into hot steam at a temperature of 450 ℃ or more and being fed to the oxidation zone D by an upward flow. The heat-sink stream in countercurrent from the oxidation zone D is cooled.

Instead of the supply of fresh water, it is also possible to supply a condensate mixture which is accumulated in the gas cooling device 10 and which consists essentially of water and small amounts of macromolecular organic compounds. Such compounds do not affect the process of the present process but make the disposal of the condensate mixture more difficult.

Said efficient energy recovery is achieved by passing the waste heat zone E and the after-cooling zone F, wherein the refractory bulk material is cooled to such an extent that the ash and fines can be separated by a filter device 12 or other separation device. The already mentioned circulation of the coarse bulk material at 13 can be effected by mixing with the new high-carbon substance 14 via the bulk material receiver 3. The loss of the coarse bulk material, which is caused, for example, by mechanical wear, can be compensated for by the supply 15 of fresh coarse bulk material.

In the upper part of the shaft calciner the gas from the oxidation zone D and the gas from the pre-degassing zone B are mixed to form a gas mixture containing dust and soot, which is thermally reprocessed in a flue-flow regasification zone at temperatures of 500-1000 ℃ with water vapor. The required steam can be introduced as desired via a feed 16, but can also be generated by using the moisture-containing high-carbon material in the drying zone a and utilized in the flue-stream regasification zone G by flowing upwards.

In order to constantly set the optimum temperature range in this region, a gas burner 17 is provided. The gas burner may be operated with an excess of oxygen-containing gas 18 relative to the combustion gas constituents 19 in the burner 17 to ensure the re-gasification of soot particles and other organic particles in the synthesis gas.

Depending on the intended utilization of the synthesis gas, different process steps can be employed to further treat the gas after leaving the flue stream gasification zone. Efficient dust and condensate separation is required since the cleaned synthesis gas should be used, for example, as a material basis for a marketable gas for later chemical or similar applications. The separation of dust is achieved by filtration of the hot synthesis gas at 20 at a temperature of 300 ℃. about.600 ℃ wherein the gas/dust mixture is drawn off from the flue gas gasification zone G by means of a gas blower 21 through a high temperature resistant filtration system 20. The negative pressure described above can also be generated in the apparatus by means of the gas blower 21.

The filtered filter dust may still contain non-gasified soot constituents which can be utilized by returning a portion of the filter dust to the oxidation zone D at 22. In the filter dust, which also serves as a desired reduction of harmful substances in the process according to the invention, a large number of impurities are still bound as a result of the process conditions, which impurities are produced from the high-carbon substances used by adsorption (e.g. heavy metals) and/or by reaction (e.g. halides). In the case of the use of the relevant carbonaceous material, therefore, a partial flow of filter dust in the process must be removed at 23, which must be cleaned.

Immediately after hot gas filtration, the synthesis gas is separated from condensates such as water and minor amounts of trace high molecular organic fission products, preferably immediately by cooling to a temperature below 50 ℃, before it is used for other purposes (at 24). The condensate produced here is essentially water, which originates from the residual moisture of the high-carbon substances used and from the partial combustion of hydrogen. In addition, these condensates also contain traces of high molecular weight organic compounds (pyrolysis oils). This condensate mixture must be returned to the process either as waste, or preferably as reaction water and carbon support (at 11) as already mentioned. Another advantageous method can be realized by the following measures: a portion of the condensate mixture from the gas cooler is continuously returned as a quench medium to the head of the gas cooler (at 25 deg.f), thereby achieving effective gas cooling while avoiding the formation of scale on the gas cooler.

The synthesis gas thus purified can in principle also be decomposed into its constituents by means of air decomposition devices or pressure swing adsorption processes and/or used as fuel for combustion in gas engines.

The synthesis gas produced in the flue stream gasification zone can also be used for direct power generation and/or for steam production if the quality of the high carbon species used allows the produced synthesis gas to be directly combusted without gas filtration and cooling. This process is illustrated in fig. 2, where the synthesis gas is introduced directly from the flue gas gasification zone G into the combustion chamber H without further treatment and is combusted without any pretreatment. The internal energy of the generated hot gas is thermally utilized to generate high pressure steam in the steam generator I. The steam is decompressed by a steam turbine J and converted into electric current 26. On the low-pressure side of the steam turbine, the remaining steam can be further thermally utilized as a heating medium.

The exhaust gas from the steam generator still contains a certain dust content, which can be separated by an exhaust gas filter K. Depending on the degree of pollution or the quality of the high-carbon substances used, the exhaust gases are then optionally treated by an exhaust gas purification device L and/or a deoxidation device M in order to meet the legal environmental protection requirements for atmospheric emissions.

The invention is illustrated by the following examples, but is not limited thereto.

Examples of the invention

A total of 6 examples are presented, which differ from one another by the use of different high-carbon substances, which examples are carried out in a standardized manner. These different application materials, their qualities and the results obtained therefrom are recorded in detail in tables 1 to 4 below.

A lime shaft kiln (2.2 m net diameter and 14.1m shaft height) was operated using heavy fuel oil through a burner lance as the primary combustion system in the oxidation zone. Calcined limestone with a particle size of 0.5 to 6cm is used as refractory bulk material and is guided in a continuous flow (see table 1, column c) in a circulating manner from top to bottom through the lime shaft furnace; at the same time, the high-carbon material (see table 1, column a) is admixed to the circulating bulk material in a continuous stream (see table 1, column b) before entering the upper kiln zone. The basic combustion system (see Table 1, columns d and e) is adjusted in such a way that the gas temperature at the gas outlet of the lime shaft kiln reaches 600 to 700 ℃. In the course of the further metering, so much air is continuously metered through the bottom of the reactor (see 1, column g) until an ash with almost no carbon is constantly obtained at the reactor outlet. The gas produced is led through a hot gas filtration system at a gas temperature of 450 ℃ and subsequently cooled to 30 ℃ via a gas cooler.

The condensate mixture (essentially water and a small amount of organic oil) produced in the gas cooler is temporarily stored.

Depending on the composition of the high-carbon substance used, so much water is continuously dosed to the oxidation zone that complete gasification of the initial carbon input is ensured. For this purpose, the temporarily stored condensate mixture and additional fresh water were used (see table 1, column f).

TABLE 1

Use amount (continuous ingredient)

The compositions and masses of the high-carbon substances used in examples 1 to 6 are shown in the columns a to e of Table 2.

TABLE 2

The gas produced in these examples was measured after the gas cooler by a gas quantity measuring device and analyzed by an on-line calorific value analyzing device. The average gas flow is shown in column a of Table 3, and the lower limit heating value is shown in column b of Table 3. The flow rates of the water-containing condensate phase resulting from gas cooling (table 3, column c) and the oil phase resulting from gas cooling (table 3, column d) were also determined. The ash produced was continuously sieved out of the coarse bulk material after the reactor and the fine coarse fraction (particle size < 3mm) was determined. The flow rates obtained are shown in column e of Table 3.

TABLE 3

The gas produced in these examples, after cooling the gas, is analyzed for its composition by an on-line analysis device. The gas composition is shown in columns a to e of Table 4.

TABLE 4

Gas component produced

Claims (24)

1. An autothermal process for the continuous gasification of high-carbon substances (14) in a vertical treatment chamber (100) having a calcination zone (C) and an oxidation zone (D), in which the high-carbon substances calcined are oxidized with an oxygen-containing gas, wherein gaseous reaction products are removed at the upper side (G) of the vertical treatment chamber (100), which vertical treatment chamber is designed in the form of a shaft furnace (100) which is continuously flowed through from top to bottom by a cyclically guided bulk material (13) which is not oxidized in itself, the high-carbon substances (14) being added to the bulk material (13) before entering the shaft furnace inlet (3), characterized in that: the oxygen-containing gas is introduced at least partially below the oxidation zone (D), thereby causing an ascending gas flow, wherein the bulk material and the ash product are cooled in the waste heat zone (E) to a temperature of up to 450 ℃ by the ascending gas below the oxidation zone (D), and furthermore the oxygen-containing gas is introduced at least partially below the lower end (4) of the shaft furnace (100) and the bulk material is cooled in countercurrent in a recooling zone (F) located below the waste heat zone (E) until the bulk material is removed from the shaft furnace to a specific temperature below 100 ℃ for energy recovery, and the reaction gas produced is withdrawn on the upper side of the shaft furnace (100) and is reprocessed in a flue-flow regasification zone (G) at a temperature of 500 ℃ to 1000 ℃ with steam.

2. The method of claim 1, wherein: the reaction gas produced is reprocessed in a flue gas stream regasification zone (G) at a temperature of 600 ℃ to 800 ℃.

3. The method of claim 1, wherein: the added bulk material (3) together with the carbonaceous material (14) is first dried in a drying zone (A) while being heated to a characteristic temperature of 20 ℃ to 100 ℃ and then pre-degassed in a pre-degassing zone (B) while continuing to be heated to a characteristic temperature of 100 ℃ to 450 ℃ in a countercurrent manner using an ascending gas above the calcination zone (C).

4. A method according to any one of claims 1 to 3, characterized in that: in the waste heat zone (E) water is supplied, which promotes cooling when vaporized, wherein the water vapor produced rises with the gas stream into the oxidation zone (D).

5. A method according to any one of the preceding claims 1 to 3, characterized in that: supplying water to the oxidation zone (D).

6. The method of claim 5, wherein: the thermal energy in the flue stream regasification zone (G) is provided by combustion of a supplied mixture of fuel (17) and a stoichiometric or superstoichiometric oxygen-containing gas.

7. The method of claim 6, wherein: the water vapour in the flue stream regasification zone (G) is provided by water (16), a supply of water vapour or by water vapour escaping in the drying zone (a).

8. The method of claim 1, wherein: the bulk material is at least partially composed of inert mineral, ceramic or metallic materials, the particle size of which is up to 20 cm.

9. The method of claim 1, wherein: basic calcine or calcine precursors with a particle size of at most 20cm are used as bulk material at least partially.

10. The method of claim 9, wherein: as bulk material, a mixture of coarse material and fine material can be used, the particle size of the coarse material being up to 20cm and the particle size of the fine material being less than 2 mm.

11. The method of claim 10, wherein: the gas withdrawn is filtered, wherein the fines contained as dust in the gas withdrawn are filtered out.

12. A method according to claim 10 or 11, characterized in that: the bulk material is filtered to separate fines from the bulk material stream.

13. The method of claim 11, wherein: returning the filtered dust to the bulk material circulation wholly or partially.

14. The method of claim 1, wherein: the process is carried out at a pressure in the range from-200 mbar to 1000 mbar.

15. The method of claim 14, wherein: a slight negative pressure is generated in the shaft kiln (100).

16. The method of claim 1, wherein: the temperature in the oxidation zone is maintained below 1800 ℃.

17. The method of claim 1, wherein: the shaft furnace has a single chamber in which the individual process zones are established.

18. The method of claim 1, wherein: the bulk material is moved through the shaft kiln by its gravity.

19. The method of claim 1, wherein: oxygen-containing gas and/or fuel is added to the oxidation zone (D) to start the process and/or to control the location, temperature and size of the various process zones (A, B, C, D, E, F) in the vertical kiln (100).

20. The method of claim 1, wherein: plastic residues, bitumen, cellulosic chips, soiled wood residues or greasy dirt are used as high-carbon substances and the method is accordingly designed as a waste treatment method for special waste materials containing carbon.

21. The method of claim 20, wherein: as high-carbon substances, materials having sides of up to 40cm were used.

22. The method of claim 8, wherein: the particle size is between 1 cm and 8 cm.

23. The method of claim 9, wherein: the particle size is between 1 cm and 8 cm.

24. The method of claim 9, wherein: the calcined product was CaO.