EP0745114B1 - Process for generating burnable gas - Google Patents

Abstract

PCT No. PCT/EP95/00443 Sec. 371 Date Aug. 14, 1996 Sec. 102(e) Date Aug. 14, 1996 PCT Filed Feb. 8, 1995 PCT Pub. No. WO95/21903 PCT Pub. Date Aug. 17, 1995A process is disclosed for generating burnable gas by gasifying water- and ballast-containing organic materials, be it coal or garbage. The drying, low temperature carbonization and gasification steps are carried out separately. The heat taken form cooled gasified gas is supplied to the endothermic drying low temperature in low temperature carbonation stages. The low temperature carbonization gas is burned in a melting chamber furnace with air and/or oxygen or oxygen-rich flue gas and the liquid slag is evacuated, whereas the low temperature carbonization coke is blown into the hot combustion gases that leave the melting reactions which take place and give carbon monoxide and hydrogen reduce the carbon is removed from the gasified gas, supplied to the melting chamber furnace and completely burned. The advantage of the invention is that the ashes may be transformed into an elution-resistant granulated building material, in that a tar-free burnable gas is generated and in that oxygen consumption is strongly reduced in comparison with the fly stream gasification process.

Description

The invention relates to a method for producing fuel gas from water and ballasted organic substances such as coal, municipal and industrial Sludge, wood and biomass, municipal and industrial waste and refuse as well as waste products, residues and others.

The invention can be used in particular for energy recovery of biomass and wood from cyclically cultivated agricultural areas, especially recultivated mining areas and thus for the design of carbon dioxide neutral Converting natural fuels into mechanical and Thermal energy and for the useful disposal of municipalities, Commercial, agricultural and industrial waste, other organic waste, Residues, by-products and waste products.

The prior art is characterized by a large number of proposals and practical applications for the energetic use of plants as well organic waste to municipal, commercial, industrial and waste Agriculture. One in November 1981 from the Jülich nuclear research facility GmbH held seminar summarizes the state of the art in thermal Gas generation from biomass, i.e. the gasification and degassing together, that too still largely characterizes the state of the art today (report of the nuclear research facility Jülich - Jülconf-46). Procedures determine accordingly for combustion, degassing and gasification individually or in combination State of the art with the following objectives: - Production of combustion gas as Thermal energy source for steam generation by combustion, - production of high calorific solid and liquid fuels such as coke, charcoal and liquid, oil-like tars through smoldering, degassing and gasification, - production of fuel gas while avoiding solid and liquid fuels through complete Gasification.

In the gasification process, the process management decides whether the receive liquid and large molecular carbonization products or also by Oxidation be gasified.

The oldest type of gasification is fixed bed gasification, where fuel and Gasification agents are moved in countercurrent to each other. This procedure achieve the highest possible gasification efficiency with the lowest possible Oxygen demand. The disadvantage of this type of gasification is that in Gasification gas the fuel lamp and all known liquid smoldering products are included. This type of gasification also requires lumpy fuel. The gasification in the fluidized bed, known as Winkler gasification, eliminated this lack of fixed bed gasification largely, but not completely. When gasifying bituminous fuels e.g. not always the necessary Freedom from tar of the gasification gas as used for the application of the gas Fuel required for internal combustion engines is reached. Furthermore is due to the higher average temperature level during process control compared to fixed bed gasification the oxygen consumption clearly higher. In addition, the temperature level of the Winkler gasification has the consequence that a large part of the carbon input is not converted into fuel gas, but in the form of dust and, bound to the ashes, from the process again is carried out. This lack of gasification technology can be compensated with the high temperature entrained flow gasification processes, which are usually above the melting point the ashes work, be avoided.

An example of this is DE 41 39 512 A1. In this procedure Waste is broken down by carbonization into carbonization gas and carbonization and thus into one required for gasification in an exothermic entrained-flow gasification Form prepared. The transition to exothermic entrained flow gasification is combined with increasing oxygen demand and decreasing efficiency, although the organic matter of waste is almost entirely in Fuel gas is converted. The causes are the high temperature level of these gasification processes, which have the consequence that a large part of the Fuel heat is converted into physical enthalpy of the fuel gas.

The lack of these technical solutions, as is inherent in DE 41 39 512, was of course recognized by the international experts and with new ones Proposed solutions answered. The latest state of the art in gasification of coal is characterized in that a partial stream of coal in a Melting chamber combustion is burned to hot combustion gas, which in the Progress of the process is used as a gasifying agent. By bringing in of the second coal partial flow into the hot gasification agent become the prerequisites created for endothermic gasification, and the combustion gas converted into fuel gas using the Bouduard and water gas reactions. This type of gasification is used in Japan in the NEDO project and in the USA for the WABASH RIVER project. For wood, residues and waste this type of gasification is not suitable because these substances only have a high mechanical effort in the dust form required for this process can be transferred.

DE 42 09 549 remedies this deficiency by combining partial flow combustion / endothermic Entrained flow gasification a pyrolysis for thermal Preparation of the fuels, especially waste materials, upstream. The lack this method, however, is that here the hot gasifying agent by combustion of pyrolysis coke with air and / or oxygen and that Olefins, aromatics and others containing smoldering gas is used for the reduction.

Many years of experience from the practical operation of gasification plants but show that olefin and aromatic fuel gases at temperatures up to 1500 ° C and endothermic process control not in tar-free fuel gas as it is for use as fuel gas for gas turbines and engines is required can be converted. The main lack of this litigation is therefore that in the course of the necessary gas cooling and treatment, aqueous Gas condensates occur that are not released into the environment in this form can, so that considerable effort is required to prepare them.

The invention aims to provide a process for the gasification of organic substances, in particular water and ballast, to propose that the inorganic Share of these substances as a glazed, elution-resistant product and the organic Substance of these substances to tar-free fuel gas, which also converts to synthesis gas can be converted, compared to the prior art Entrained-flow gasification lower consumption of oxygen-containing gasifying agent as well as compared to the fluidized bed process and entrained-flow gasification higher gasification efficiency, based on the applied chemical Enthalpy of the fuel gas.

The technical problem to be solved by the invention is to provide a portion of the physical enthalpy required for reaching the temperature level above the melting point of the inorganic portion of the substances to be gasified is required to return to chemical enthalpy as the process continues convert.

• ersten Prozeßstufe die ballastreichen organischen Stoffe mit ihren organischen und Wasseranteilen durch direkte oder indirekte Zuführung von physikalischer Enthalpie des Vergasungsgases getrocknet und bei 350 bis 500° C geschwelt und damit in Schwelgas, das die flüssigen Kohlenwasserstoffe und den Wasserdampf enthält, und Koks, der neben dem anorganischen Anteil hauptsächlich Kohlenstoff enthält, thermisch zerlegt werden,
• zweiten Prozeßstufe das Schwelgas bei Temperaturen oberhalb der Schmelztemperatur des anorganischen Anteiles der organischen Stoffe mit Luft und/oder Sauerstoff, sauerstoffhaltigen Abgasen, z.B. aus Gasturbinen oder Verbrennungsmotoren, vorzugsweise bei 1200 bis 2000° C, unter Abscheidung von schmelzflüssigem anorganischem Anteil mit einer Luftzahl von 0,8 bis 1,3 bezogen auf den theoretischen Luftbedarf für die vollständige Verbrennung zu Verbrennungsgas verbrannt wird,
• in einer dritten Prozeßstufe das Verbrennungsgas aus der zweiten Prozeßstufe in Vergasungsgas umgewandelt und die Gastemperatur auf 800 bis 900° C abgesenkt wird, indem Schwelkoks aus der ersten Prozeßstufe, ggf. aufgemahlen zu Brennstaub, in das 1200 bis 2000° C heiße Verbrennungsgas eingeblasen wird, der das Kohlendioxid teilweise zu Kohlenmonoxid und den Wasserdampf teilweise zu Wasserstoff wärmeverbrauchend reduziert,
• vierten Prozeßstufe das Vergasungsgas aus der dritten Prozeßstufe, ggf. nach indirekter und/oder direkter Kühlung, zu Brenngas aufbereitet wird, in dem es entstaubt und chemisch gereinigt und der dabei anfallende, noch Kohlenstoff enthaltende Staub der Verbrennung des Schwelgases in der zweiten Prozeßstufe zugeführt wird.

According to the invention this is achieved by under a pressure of 1 to 50 bar

• first stage of the process, the ballast-rich organic substances with their organic and water components by direct or indirect supply of physical enthalpy of the gasification gas and dried at 350 to 500 ° C and thus in carbonization gas, which contains the liquid hydrocarbons and water vapor, and coke, which besides the inorganic content mainly contains carbon, can be thermally decomposed,
• second process stage the carbonization gas at temperatures above the melting temperature of the inorganic portion of the organic substances with air and / or oxygen, oxygen-containing exhaust gases, e.g. from gas turbines or internal combustion engines, preferably at 1200 to 2000 ° C, with separation of molten inorganic portion with an air ratio of 0 , 8 to 1.3 based on the theoretical air requirement for complete combustion is burned to combustion gas,
• in a third process stage, the combustion gas from the second process stage is converted into gasification gas and the gas temperature is lowered to 800 to 900 ° C by blowing coke from the first process stage, possibly ground to fuel dust, into which combustion gas with a temperature of 1200 to 2000 ° C is blown, which partially reduces the carbon dioxide to carbon monoxide and the water vapor to hydrogen,
• fourth process stage, the gasification gas from the third process stage, if necessary after indirect and / or direct cooling, is processed into fuel gas in which it is dedusted and chemically cleaned and the resulting carbon-containing dust is fed to the combustion of the carbonization gas in the second process stage .

The benefit of the invention is that the inorganic substance contains ballast, organic materials into a glazed, elution-resistant building material is reduced when the need for oxygen-containing gasifying agent is reduced the level of fluidized bed gasification and complete gasification of the organic matter at a temperature level that the Winkler gasification corresponds to and, measured by the chemical enthalpy of the fuel gas, higher gasification efficiency compared to the prior art.

Embodiment

The invention is achieved with the aid of the rough technical diagram shown in FIG and the following computational estimate.

An organic material containing water and ballast, a garbage-containing biomass of the following composition (in kg / t) is used as the input material: component Dimensions carbon 250 hydrogen 25th oxygen 150 nitrogen 8th sulfur 2nd Heavy metals (Pb, Cd, Hg, Cu, Zn) 3rd ash 100 Iron / non-ferrous metal 30th Glass / minerals 112 water 320.

This material is cut to an edge length of 20 to 50 mm in a shredder (1) crushed and indirectly via a gas-tight lock system (2) heated smoldering chamber (3) working under normal pressure, in which the feed material is moved mechanically if necessary. Through the indirect Heat supply (4) dries and smoldered the feed, it disintegrates a final temperature of 400 to 500 ° C in approx. 405 kg of solid, which is approximately too 40% carbon, while the rest is mineral, Glass, iron and non-ferrous metals as well as heavy metals and ashes, and 595 kg Smoldering gas, which consists of almost two thirds of water vapor, and all contains other known liquid and gaseous smoldering products.

The solids from the carbonization are in carbonization gas in a sieve (5) a coarse fraction mainly containing minerals, glass and scrap metal with an edge length greater than 5 mm and a small-grain carbon carrier Cut. The coarse fraction is extracted from the via gas-tight lock systems (6) Process carried out and possibly passed to a separation. The carbon carrier remains in the system and is passed through a continuous mill (7) and via a pneumatic conveying system (8), the recirculated fuel gas as the conveying medium used, fed to a reduction chamber (9). The inorganic part of Carbon carrier is used with that in the reduction chamber (9) Carbon separated in a gas dedusting (10) and together with the in the smoldering chamber (3) produced smoldering gas from a smelting chamber combustion (11) supplied and there with oxygen above the melting temperature of the inorganic substance of the carbon carrier burned. The resulting one Liquid slag is discharged into a water bath (12) and from there as elution-resistant Building material granules removed from the process. That means 1200 to 2000 ° C Combustion gas enters the reduction chamber from the melting chamber furnace (11) (9), where part of its carbon dioxide and water vapor is associated with the Carbon carrier reacts endothermically to carbon monoxide and hydrogen, whereby the gas temperature drops to 800 to 900 ° C. The feeding of the in the gas dedusting (10) accumulating carbon-containing dust Melting chamber firing (11) is also carried out with a pneumatic conveyor system (13), which uses recycled fuel gas as the carrier medium. That so The fuel gas generated corresponds in its composition to a fuel gas that at 800 to 900 ° C during the gasification of the organic matter of the feed with oxygen under normal pressure. It is comparable to an after the gasification gas generated in the fluidized bed gasification process when used an oxygen-water vapor mixture as a gasifying agent.

Claims (2)

1. Process for generating burnable gas from organic materials, in particular water- and ballast-containing ones, such as coal, sludges, garbage, wood and other biomasses, using the known process stages of drying, low-temperature carbonization and gasification, characterized in that, under pressures of I to 50 bar, in a first process stage, the ballast-rich organic materials are dried by direct or indirect supply of physical enthalpy and subjected to low-temperature carbonization at 350 to 500°C and are thus thermally decomposed into low-temperature carbonization gas, which contains the liquid hydrocarbons and the steam, and coke, which principally contains carbon, in addition to the inorganic portion, in a second process stage, the low-temperature carbonization gas is burnt with air and/or oxygen, oxygen-containing exhaust gases, e.g. from gas turbines or internal combustion engines, at temperatures above the melting temperature of the inorganic portion of the organic materials, preferably at 1200 to 2000°C, with removal of molten inorganic portion, to form combustion gas, in a third process stage, the combustion gas from the second process stage is converted into gasification gas and the gas temperature is decreased to 800 to 900°C, by blowing low- temperature carbonization coke from the first process stage, if appropriate ground to give pulverized fuel, into the combustion gas at 1200 to 2000°C, which coke partially reduces the carbon dioxide to carbon monoxide and partially reduces the steam to hydrogen, with consumption of heat, in a fourth process stage, the gasification gas from the third process stage, if appropriate after indirect and/or direct cooling, is processed to give burnable gas, by dedusting it and chemically cleaning it, and feeding the still carbon containing dust, produced in the course of this process, to the combustion of the low-temperature carbonization gas in the second process stage.
2. Process according to Claim 1, characterized in that the heat requirement of the first process stage is covered by some of the enthalpy of the gasification gas from the third process stage or of the burnable gas of the fourth process stage.

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