DE102006059094B4 - Fuel briquette from partially composted biomass and process and apparatus for its production - Google Patents

Abstract

A process for the production of fuel briquettes from teilkompostierter biomass, characterized in that a) biogenic waste without detailed treatment, such as mechanical comminution and screening are preferably subjected to a multi-stage Rectangle, wherein the biomass aerated by reacting and the water content of about 70% to 38-40 b) that the partially composted biomass is sieved prior to transfer and into a compost fraction having a grain size of 3 to 15 mm, middle fraction, a sieve overflow having a particle size of 15 to 70 mm and coarse fraction, an oversize fraction greater than 70 mm and medium and coarse fractions are added for further drying until the water content is reduced to about 25 to 35%, c) that the compost fraction is separated, d) that the coarse fraction is comminuted to a particle size corresponding to the middle fraction e) that of the middle fraction and crushed coarse fraction still a f) that the calorific value of the remaining fuel fraction is determined and adjusted by admixing additives to 14000 to 21000 kJ / kg g) and that the so prepared mass compacted by means of twin screw extruder into a fuel briquette and simultaneously or subsequently with a drying plant (claim 10) is dried to a moisture content ≤ 20 wt .-%.

Description

The invention relates to fuel briquettes from teilkompostierter biomass and a method and a plant for their production.

According to Biomass Regulation, biomass includes biowaste and green waste, renewable raw materials, waste and by-products of plant and animal origin from agriculture and forestry, and waste wood without pollutants. Biowaste includes biological waste from household and food production. Green waste is garden and park waste, organic material from the landscape, as well as tree and shrub intersection.

It is known to compost biowaste, such as green waste, garden waste and leftovers from municipal collection. After a rotting time of about 10 weeks, coarse and difficult to compost substances are separated from already rotted components and fed to a new Rottedurchlauf. The higher the proportion of materials that are difficult to compost in the input material, the higher the recirculation and the operating costs rise accordingly.

Composting methods currently in use are rent composting with or without aeration and tunnel composting with air ducting. The composting time lasts 8 to 12 weeks, until the rotted material can be screened to compost. The grain size ranges between 10 to 25 mm. The over-grain from 25 mm, the so-called screen overflow, goes back into the composting cycle and causes considerable costs until the woody parts have become completely compost.

In DE 199 09 328 A1 a method is described in which high-energy organic components after mechanical treatment (crushing, sieving, removal of contaminants) of commercial and household waste by aerobic hydrolysis are degraded as completely as possible. High-energy compounds are washed out before compaction of the thus treated fine-grained fraction.

After drying the biologically stabilized via the hydrolysis waste this is briquetted. In this case, a small proportion of an organic-containing coarse fraction (screen overflow), bypassing hydrolysis and drying is fed directly to the compaction. Drying of the mixture is carried out by a occurring during the pressing process heating of the material to be pressed. Plastic components fuse and serve as binders.

The biological stabilization by aerobic hydrolysis makes a loading and drainage necessary, the leaching is additionally fed to a wastewater treatment plant. The high-energy substances contained therein are utilized in a biogas plant and are therefore not available for energy production by direct combustion.

The composition of the briquettes in this process is determined solely by the composition of the waste to be processed. Aggregates are not added. In addition, hard materials to be deposited are not separated.

In an in DE 196 11 728 A1 biologically stabilized waste is "stabilized" after optional mechanical treatment biologically for only 7 days in a rump. This is followed by another comminution step, followed by another 2 rotted runs. After removal of gross impurities, unspecified input materials are added to the waste. The thus treated waste is mixed into bales or briquettes and irradiated with microwaves.

The briquettes produced are characterized by a large variety of materials. A selection of a fuel-rich fraction does not take place. The compacts are not intended for thermal utilization.

In DE 34 02 215 A1 the extraction of a fuel fraction from waste and sewage sludge is described, which is added to a compacting to increase the calorific value wood, bark and straw. Part of the briquettes is coke from the pollination of sewage sludge. Another composition of the components used for combustion is not described. An optimization of the condensing properties is possible only to a very limited extent. The emission behavior can be considered as problematic due to the largely unknown composition.

In DE 34 02 215 it is stated that the briquetting of waste and sewage sludge requires a considerable evaporation of water. It was attempted, a kind of biological predrying of the crushed mixture in a rotting plant. The expense of previously known systems is after DE 34 02 215 uneconomical. Above all, the wear costs are enormous in the crushing plants and also in the briquetting and pelleting machines. Unless energy-intensive hot-drying is used for an extended period of time prior to briquetting, the briquettes are not hygienically flawless. Above all, such briquettes disintegrate under the influence of moisture and begin to rot or rot, for example when they are in the rain or when wet Air transported or stored. In contrast, briquettes made from shredded refuse and crushed coal are better (waste and waste booklet 1283, pages 308 and 309). However, this method requires a separate coal grinding plant, which is profitable only at high throughput, for example, for a pulverized coal fired power plant.

In DE 196 42 161 A1 and DE 34 22 912 A1 The briquetting of treated waste for energy recovery is also described. In this case, however, binders are added for compaction, which make the product more expensive.

The briquettes are in DE 196 42 161A1 from residual waste materials which may be mixed with toxic components. Starting ingredients in DE 34 22 912 A1 are naturally moist comminuted biomass from agricultural, garden and forestry waste and domestic and industrial waste components.

WO 96/23046 A1 discloses a secondary fuel from rotted waste wherein the waste is fed to an intensive rotting, then to post-rotting and drying. Such rotted waste should be immediately usable as fuel. Since the rotted waste completely, only diminishes to impurities, directly after the production of the secondary fuel WO 96/23046 A1 before decay, the carbon-to-nitrogen ratio of the waste must be set concretely to a value of 30-40: 1 before rotting. Furthermore, it is necessary to nachgetrocknen the rotted mass.

Object of the present invention is to utilize biowaste with high added value and for combustion energy conversion by pyrolysis.

According to the invention the object is achieved by a method for producing fuel briquettes from teilkompostierter biomass having the features of claim 1. Further embodiments include the features of the subordinate claims 2 and 3. The invention also includes a fuel briquette with the features according to patent claim 4 and a plant for the production of fuel briquettes from teilkompostierter biomass a composting with the features of claims 5 to 7.

The fuel briquet prepared by the process according to the invention consists of extruded teilkompostierter biomass and additives
with a share off
75 to 85% of partially composted biomass
15 to 25% additives
a calorific value between 14,000 to 21,000 kJ / kg and an ash content <20% by mass.

In this context, biomass refers to the entirety of organic substances of biological origin usable for material and energy purposes, including biogenic waste.

The additives include not a rotting process, mechanically comminuted biogenic aggregates with partly fibrous structure such. Eg cotton, straw, sawdust, leather residues, fermentation residues, cellulose and paper waste, spent grains

The fuel briquettes are made as follows:

1. Rotting biomass

Biogenic waste is preferably subjected to a multi-stage rinse run without thorough treatment, such as mechanical comminution and screening, whereby the biomass is aerated by reaction or mechanically.

The aim of the decomposition of the biomass is the production of compost and the reduction of the water content from about 70% to 38-40%. The degradation of carbonaceous compounds should be kept low.

In an advantageous embodiment of the invention, patch biomass rivings are implemented every 8 to 10 days. Within about 4 weeks, the water content is reduced to 38-40%.

2. Separation of a fine-grained compost fraction from a middle and coarse fraction

• a) Kompostfraktion mit einer Korngröße von 3 bis 15 mm,
• b) Mittelfraktion, einem Siebüberlauf mit einer Korngröße von 15 bis 70 mm und
• c) Grobfraktion, einer Überkornfraktion größer 70 mm

getrennt. Beim Sieben werden Störstoffe, z. B. durch Magnete magnetische Bestandteile herausgelöst. Die Kompostfraktion wird der weiteren Kompostierung zur Herstellung von Kompost zugeführt. Mittel- und Grobfraktion werden zur weiteren Trocknung zu Mieten wieder aufgesetzt, bis der Wassergehalt auf etwa 25 bis 35% reduziert ist und sich Sand und Störstoffe besser abtrennen lassen. Dabei ist eine gezielte thermische Trocknung durch Abwärme möglich.Advantageously, the teilkompostierte biomass is sieved before converting and into a

• a) compost fraction with a grain size of 3 to 15 mm,
• b) middle fraction, a sieve overflow with a grain size of 15 to 70 mm and
• c) Coarse fraction, an oversize fraction greater than 70 mm

separated. When sieving contaminants, z. B. removed by magnets magnetic components. The compost fraction is fed to the further composting for the production of compost. Medium and coarse fractions are returned to rents for further drying until the water content is reduced to about 25 to 35% and sand and impurities can be better separated. A targeted thermal drying by waste heat is possible.

3. Preparation of the middle and coarse fraction to a fuel fraction

The coarse fraction is comminuted with a suitable hacker to a particle size corresponding to the middle fraction.

In the comminution of the coarse fraction fibrous additives such. B. mixed lumpy wood and crushed together.

After crushing the coarse fraction, both fractions of another screen, z. B. a vibrating or vibrating screen and a Hartstoffabscheider supplied in the compost shares, and sand and contaminants such as stones, potsherds, glass and other solid and hard materials are separated.

The shredded rotting material is then separated together with the middle fraction in a further screening plant in a fraction to be composted (0-5 mm) and a fuel fraction (> 5 mm). The fuel fraction is further processed for the deposition of contaminants to be deposited, such as sand, earth, stones, glass components in a hard material separator.

The ash content and calorific value of the fuel fraction are determined. By admixing fibrous additives, the calorific value is set to 14,000 to 21,000 kJ / kg and an ash content <20% by mass. Optionally, the fuel fraction is fed to a further separation process.

The water content should not exceed 25 to 35% by mass.

4. Extrusion of the fuel fraction

The treated fuel fraction is compacted to optimize the calorific value properties, storage and transport in an extruder press, preferably in a twin-screw extruder, and subsequently dried to a moisture content ≦ 20% by mass.

The composition of the product from pollutant-free biogenic hard-to-decompose wastes is largely defined and regulated by application of aggregates in variable proportions in its composition.

• – Auf eine thermische Trocknung der Brennstofffraktion bzw. auf den Zusatz von Adsorptionsmitteln („chemische Trocknung”) vor der Brikettierung wird im Hinblick auf eine kosteneffiziente Bioabfallverwertung verzichtet. Die Reduktion des Wassergehaltes auf 25 bis 35 Ma.-% wird lediglich durch Rotteumsätze und auf ≤ 20 Ma.-% durch den Brikettiervorgang erreicht. Aufwendige Trocknungsanlagen wie sie bei der Aufbereitung von Klärschlamm und direkter thermischer Verwertung naturfeuchter Biomasse notwendig sind, werden nicht benötigt.
• – Eine Erhöhung des Heizwertes wird durch Zusatz von stückigem Holz und Halmgütern erreicht. Diese Zuschlagstoffe werden bis auf eine mechanische Zerkleinerung nicht weiter aufbereitet. Der Anteil dieser Stoffe am Brennstoffbrikett kann entsprechend den Anforderungen an Heizwert, Festigkeit und Aschegehalt variiert werden.
• – Die mit dem Brikettiervorgang verbundene Temperaturerhöhung der Biomasse führt zu einer teilweisen Zerstörung der Faserstrukturen des Pflanzenmaterials. Dies ermöglicht die Brikettierung der thermisch nutzbaren Biomasse ohne den Zusatz von Bindemitteln.
• – Da für die Verwertung zu Brennstoffbriketts lediglich schwer kompostierbare biogene Stoffe eingesetzt werden, ist eine ausreichende Lagerdauer der Briketts gewährleistet.

Die erfindungsgemäßen Brennstoffbriketts zeigen ein gutes Zünd- und Ausbrandverhalten sowie eine gute Feuerstandfestigkeit. Während des Ausbrandes treten Risse auf, ohne dass es zu einem Zerfall der Briketts im Brennstoffbett aufgrund des Transportes kommt. Die Risse sind insbesondere im Hinblick auf die Stoff- und Wärmeübertragungsbedingungen, z. B. Sauerstoffzufuhr und damit für die Reaktionsbedingungen im Inneren des Briketts von Vorteil.Investigations of burnup and emissions behavior reveal no need for ancillary equipment for combustion plants (eg secondary filters) charged with the briquettes produced in the present process.

• - Thermal drying of the fuel fraction or the addition of adsorbents ("chemical drying") prior to briquetting is dispensed with in view of cost-effective biowaste utilization. The reduction of the water content to 25 to 35 wt .-% is achieved only by rotting conversions and to ≤ 20 wt .-% by the briquetting. Elaborate drying systems, such as those required in the treatment of sewage sludge and direct thermal utilization of naturally moist biomass, are not required.
• - An increase in the calorific value is achieved by adding lumpy wood and stalks. These aggregates are not further processed except for mechanical comminution. The proportion of these substances in the fuel briquette can be varied according to the requirements of calorific value, strength and ash content.
• - The temperature increase of the biomass associated with the briquetting process leads to a partial destruction of the fiber structures of the plant material. This allows the briquetting of the thermally usable biomass without the addition of binders.
• - Since only hard to compostable biogenic substances are used for the fuel briquettes, a sufficient shelf life of the briquettes is guaranteed.

The fuel briquettes according to the invention show a good ignition and burnout behavior and a good resistance to fire. During burnout, cracks occur without the briquettes in the fuel bed disintegrating due to transportation. The cracks are particularly with regard to the material and heat transfer conditions, eg. As oxygen supply and thus for the reaction conditions in the interior of the briquette of advantage.

Advantages of briquetting

• • Reduction of storage volume to a fraction of normal capacity
• • Minimization of transport and storage costs
• • Briquetting reduces dust immissions and prevents dust explosions
• • Briquettes made from biomass and wood waste provide valuable fuel
• • Burning properties of the biomass are increased (drying, selective mixing)
• • environmentally friendly, cost-saving briquetting without binders
• • Recycling the compost fraction

According to the invention the plant for the production of fuel briquettes from teilkompostierter biomass a composting at least one mixer / dosing for teilkompostierte biomass as a fuel fraction, according to a determination of ash content and calorific value additives are admixed so that a calorific value of 14000 to 21000 kJ / kg and a Ash content <20 mass%, and an extruder coupled thereto for compacting the fuel fraction with the fibrous additives.

A chopping device for the partially composted biomass is arranged such that a coarse fraction of the partially compostable biomass is comminuted to a particle size corresponding to the middle fraction before being fed to the mixer / doser. Furthermore, a hard material separator for the partially compostable biomass is arranged so that prior to mixing / metering in the mixer / doser to be dumped impurities are removed from the biomass. After the extruder, a drying plant for the compacted fuel fraction with the fibrous additives is arranged as fuel briquettes, wherein the fuel briquettes are dried to a moisture content ≤ 20% by mass.

In an advantageous embodiment, the plant for producing fuel briquettes consists essentially of a composting plant, at least one screening plant, at least one hard material separator, a chaffing device, a biomass storage, a mixer / dosing device and a twin-screw extruder. The screen is preferably designed as a vibrating or vibrating screen and has magnetic separator.

Claims (8)

A process for the production of fuel briquettes from teilkompostierter biomass, characterized in that a) biogenic waste without detailed treatment, such as mechanical comminution and screening are preferably subjected to a multi-stage Rectangle, wherein the biomass aerated by reacting and the water content of about 70% to 38-40 b) that the partially composted biomass is sieved prior to transfer and into a compost fraction having a grain size of 3 to 15 mm, middle fraction, a sieve overflow having a particle size of 15 to 70 mm and coarse fraction, an oversize fraction greater than 70 mm and medium and coarse fractions are added for further drying until the water content is reduced to about 25 to 35%, c) that the compost fraction is separated, d) that the coarse fraction is comminuted to a particle size corresponding to the middle fraction e) that of the middle fraction and crushed coarse fraction still a f) that the calorific value of the remaining fuel fraction is determined and adjusted by admixing additives to 14000 to 21000 kJ / kg g) and that the so prepared mass compacted by means of twin screw extruder into a fuel briquette and simultaneously or subsequently with a drying plant (claim 10) is dried to a moisture content ≤ 20 wt .-%. A method according to claim 1, characterized in that are used as additives not a rotting process, mechanically comminuted biogenic aggregates with partly fibrous structure. A method according to claim 1 or 2, characterized in that the additives are selected from cotton, Halmgütern, sawdust, leather residues, fermentation residues, cellulose and paper waste or spent grains. Fuel briquette, consisting of an extruded fuel fraction consisting of a middle and coarse fraction of a partially composted biomass and additives, containing 75 to 85% of the middle and coarse fractions of the partially composted biomass, 15 to 25% additives, with a calorific value of 14000 to 18000 kJ / kg, and an ash content of <20% by mass, and a water content of <20% by mass, obtainable by a process according to any one of claims 1 to 3. Plant for the production of fuel briquettes from partially composted biomass of a composting plant according to a method according to any one of claims 1 to 3 with a mixer / doser for teilkompostierte biomass as a fuel fraction, wherein according to a determination of ash content and calorific value additives are admixed so that a calorific value of 14,000 to 21,000 kJ / kg and an ash content <20% by mass, and a twin-screw extruder coupled thereto for compacting the fuel fraction with the fibrous additives. Plant according to claim 5, characterized in that a chopping device for the partially composted biomass is arranged so that a coarse fraction of teilkompostierbaren biomass is crushed before being fed to the mixer / dosing to a corresponding particle size of the center fraction. Plant according to claim 6, characterized in that a hard material separator for the partially compostable biomass is arranged so that prior to mixing / metering in the mixer / doser to be deposited impurities are removed from the biomass. Installation according to claim 7, characterized in that after the extruder, a drying plant for the compacted fuel fraction with the fibrous additives is arranged as fuel briquettes.