Incineration

Waste incineration (including waste incineration, waste treatment or recycling, in Switzerland incineration or waste incineration ), the burning of the atmospheric combustible components of waste for volume reduction of the waste using the energy contained and accompanied by the compaction of the remaining amount for further utilization or. landfilling.

Previously, with the injection of a collection of construction waste separation, waste wood, glass, small scrap paper and paperboard and of containers ( yellow bag ) to improve the economic and technical efficiency. After delivery, today there is a conditioning, so a balancing mixing the calorific value of the deliveries. In addition, there is a separate mechanical-biological waste treatment. Also, electrical appliances and electronic waste, vehicles and clothing (→ charity shop ) and shoes are treated separately.

• 7.1 exhaust
• 7.2 ash, slag and dust

• 8.1 Germany
• 8.2 Switzerland
• 8.3 Austria
• 8.4 South Tyrol

Regional differences

In Germany, the plants are distributed according to the population density. A portion of industrial waste and municipal waste has to be transported over long distances. An overview map with basic data of most plants can be found in the community of interests of thermal waste treatment facilities in Germany eV

For waste incineration are waste incinerators (MVA ) ( in Switzerland: municipal solid waste incinerator ( MSWI ) ) are used. Because today, with few exceptions, the energy contained in the waste is also used for production of electric power and / or heating (steam), incinerators are also called garbage power plant ( MKW ), Waste Heat ( MHW ) or energy from waste plant ( MHKW ) - depending on whether they only electrical energy ( power plant ) that produce only heat ( heating plant ), or both ( thermal power plant ).

Importance

The proportion of the waste that is burned in incinerators is very different world.

In industrialized countries, the portion of combustion, in particular because of the legal framework, much higher than in developing countries. In Germany, since 1 June 2005, the landfilling untreated waste is prohibited ( TA municipal waste ). Household waste must be disposed of only after its combustion in the form of slag. In Switzerland, 100 percent of the resulting domestic waste is thermally treated. Waste incineration is now preceded by a rule of the landfill because the landfill surface, especially in densely populated countries is scarce and the landfilling of incineration residues requires much less space and volume. Furthermore, no soluble pollutants are at the disposal of treated waste released and re-form only a small extent. Anaerobic degradation processes of organic fraction and by pollutants groundwater, soil and ambient air of a landfill of untreated waste is significantly impacted. Thermally treated residue with a residual content of less than 3 % carbon can be deposited on the other hand practical problems. The EU Directive 1999/31/EC limits for landfills the proportion of biodegradable components to 3%, which is why the pre-treatment of municipal solid waste is required in the Member States.

Since 2000, the amount of waste incinerated in Germany has quadrupled in 2011 and 19.7 million tons were incinerated, which is compared with the previous year, an increase of 13%. Of these, two thirds were used for energy production, 6.8 million tons in biomass power plants and 6.3 million tons in substitute fuel power plants. Otherwise accounted for 2 million tonnes to other power plants, thermal power stations and 1.2 million tonnes to 3.4 million tonnes of production facilities.

Construction

A conventional incinerator for example, consists

Types of incinerators

Incinerators are available for various purposes in different sizes and designs. Small plants are located in hospitals, in order to eliminate bacterially contaminated waste locally. There are also facilities for specific purposes such as sewage sludge incineration. Another possibility is the use of waste as secondary fuel in systems that were not built for waste disposal, for example, in rotary kilns in the cement industry. By far the largest proportion is treated in industrial plants, where the energy released is used usually in the form of district heating or to generate electricity. Combustion method is usually the burning on stove grates, partly also the fluidised bed by prior treatment of the waste. Pyrolysis and gasification plants play so far only subordinate roles.

Conditioning

The delivered waste from various sources and carts is first deposited in a mixing plant or directly in the waste bunker of the incinerator, which contributes to a conditioning of the waste for improved continuity of energy. In addition, you can set the delivered waste alternative fuels such as non-recyclable plastic films or shredded pieces of wood from the trash. The repeatedly rumored alleged addition of fuel is a myth.

Grate

In the grate no processing of the delivered residual waste is required. For loading conveyors are ( from the mixing plant ) or cranes used ( from the bunker ) to transport the waste into the feed hopper. About the loading device, consisting of a lock and the task table, the waste is transported metered into the furnace chamber. There it passes on to the grate, the conveyed waste to be transferred during the combustion phases.

There roller grates, forward or reverse thrust grates, traveling grates rarely also be used (see also Rust types). In the first zone, a drying of the waste takes place, the excess of 100 ° C followed by evaporation of the water content at temperatures. In the next zone in the temperature range of 250-900 ° C., a degassing of the waste. Upon reaching the flash point of the combustion products of decomposition sets in, the substoichiometric ( incomplete) takes place at temperatures of 800-1150 ° C. On the last grate zone of Restausbrand done.

The air supplied from below the grate, the primary air and secondary air supplied to above have a substantial influence on the combustion and the formation of reaction products. With the primary air, incomplete combustion on the grate is initiated. The air flow is metered so that a good burnout is achieved at low nitrogen oxide formation. The afterburning of the radicals ( carbon monoxide, hydrocarbons ) takes place in the post-combustion by supplying the secondary air. The combustion air volume flows can be controlled in zones and in accordance with the flue gas analysis (CO, NOx, excess air ). The combustion residues are at the end of rust in a water bath ( deslagger ) from which they are discharged via ram or scraper chain, and pass via conveyor belts to the slag processing.

The temperature in the combustion chamber depending on the system may be more than 1000 ° C. Due to the 17 BImschV the flue gases have to have a temperature of at least 850 ° C for at least two seconds after the last supply of combustion air. There are permissible lower temperatures in the combustion chamber, where compliance with the emission limits is demonstrated. To prevent the release of dioxins and other unwanted toxic compounds, the flue gases are again " afterburning ", so possibly resulting dioxins decompose.

The entire lower portion of the first train of the steam boiler is lined in order to limit the heat transfer. There is a high Nachverbrennungstemperatur is thus ensured and the tube walls are protected against corrosion at high temperatures. Due to the reduced heat transfer, the flue gas for a long time has a high temperature, and thus a degradation of complex hydrocarbons, such as dioxins and furans occurs.

The flue gas gives off heat to the heating surfaces of the boiler. However, in the following emission control system during the cooling of the residual particles again new pollutants - dioxins - arise, which is why an elaborate filtering technique is required.

Auxiliary burners ( gas or oil burners) are fired only in rare cases when starting or in poor waste calorific values ​​in order to keep the temperature in the boiler high enough.

Pyrolysis

The process steps of drying up degassing are technically referred to as pyrolysis or devolatilization. The individual steps may be carried out in a superimposed succession or combustion chamber in a plurality of reactors. Conventional systems have typically only via a combustion chamber in which to run the five individual steps in parallel. There is also pyrolysis and gasification plants, in which no Restausbrand occurs and the waste incineration plants are not, strictly speaking, since the gases are supplied to other industrial processes. Worldwide, there are but few plants using the pyrolysis process on a large scale.

Fluidised bed combustion

The fluidised bed is the usual procedure for combustion of sewage sludge, which is used increasingly for alternative fuels. However, not classified fuels such as municipal and commercial waste must be sorted and crushed prior to combustion, because the fluidized bed can hold only substances with limited size in the balance. Metals and stones damage the feed and discharge systems and must be largely removed from the fuel.

It will be used in both stationary and circulating fluidized beds for the Reststoffverfeuerung. After heating the oven with oil or gas burners of the pretreated waste or pre-dried sewage sludge is fed from a few meters height from the side onto the fluidized bed, where litter feedstocks or augers are used. In fluidized bed combustion in the bottom of the furnace, a nozzle bed (that is, a plate which is equipped with many air nozzles ) is installed. Through these nozzles, combustion air is abandoned and it is added to the sand. The fuel, the ash and sand are kept in the furnace in the balance. The good mixing of fuel and air have the consequence that a fairly uniform optimum combustion can be adjusted in the fluidized bed and stratification can be avoided by unburnt air or carbon monoxide, for example. By partial recirculation of exhaust gas, the combustion parameters can be optimized. The combustion temperatures are between 800 ° C and 900 ° C. The uniform temperature distribution caused relatively little nitrogen oxides. The discharge of the ash is carried out depending on weight over the stove hood up or down through shafts.

Hazardous waste incinerators ( rotary kiln )

For the incineration of hazardous wastes, are required for the high temperatures, rotary kilns are employed. In this technique, the waste is placed in the upper end of an inclined and slowly rotating the tube. The length of a rotary kiln for the combustion of waste can be up to 12 m, the diameter is from four to five meters. This tube is lined with refractory bricks, in order to maintain a high temperature of 1000-1300 ° C can, because in the combustion of waste requiring special supervision, which contain halogenated organic substances, a minimum temperature of 1100 degrees Celsius is observed. The lining protects the outer steel shell from corrosion and an unacceptably high temperature. The rotary kiln has the advantage that waste very different consistency and lumpiness can be burned. Thus done the task of solids, slurries, and besides drums up to 200 liters. The heating of the rotary kilns is ideally carried out with high-calorific waste solvents of at least 20,000 kJ / kg.

Calorific value

During the combustion of untreated municipal waste can be assumed in Germany from a lower calorific value of 9-11 MJ / kg. Taking into account all balance limits and efficiency of the indexing method in a classic waste incineration plant (main components: waste task; thermal main method consisting of Feststoffausbrand on a grate and steam generation in a water -tube boilers, waste gas and waste water treatment, electrical energy conversion from the hot steam) could be so about 1.3 MJ or about 0.36 kWh of electrical energy per kg wet waste. Although the municipal solid waste in accordance with the requirements of the Recycling and Waste Management Act (§ 4 para 1 KrW-/AbfG, § 6 KrW-/AbfG ) material recyclable ingredients are extracted (eg variety plastics, paper, glass ) and the boundary established for one energy recovery from waste materials at 11 MJ per kg ( § 6 paragraph 2 KrW-/AbfG ) is a self -sustaining combustion without supplementary possible. Another possibility is a " mechanical-biological pre-treatment " ( MBV ) upstream to separate, for example, low calorific value, moist organic waste and fed into a composting. And inert substances are separated in this way. The resulting increase in net calorific value of residual waste permits energy recovery. In this context, the thermal treatment of residual and waste materials is a technically useful addition of an integrated waste management system for municipal waste. The energy produced by the combustion of waste can be achieved once and are fed into thermal and / or electrical form of further use, for example by district heating. The energy balance of producing a product of the energy balance of exploitation is to relate with municipal waste that are not segregated and highly heterogeneous present in their composition due to multiple system boundaries extremely difficult. Because of the second law of thermodynamics never the total energy contained in the waste ( district heating) and / or electrical energy can be converted into useful thermal energy. In addition occur in any energy conversion also losses, for example in the form of heat losses in the reality never quite adiabatically executable boiler and Feuerungstrakte. In addition, a waste incineration plant needs a part of the generated energy for its own consumption, which additionally reduces the efficiency. Thus it can be recovered by incineration only a part of that energy which was in the raw materials of the starting materials and was required for their production.

Emissions

Exhaust

Since it is not known when the incineration of the refuse which ingredients are in what quantities burned at any given time (critical, for example, PVC, batteries and electronic components, paints, etc.), varying the composition of the flue gas and ash. During combustion are carbon dioxide and water as well as carbon monoxide, sulfur oxides, nitrogen oxides, as well as hydrochloric acid ( hydrochloric acid) and hydrogen fluoride ( hydrofluoric acid ) and mercury and heavy metal-containing dusts. In very low concentrations that highly toxic substances such as polychlorinated dibenzodioxins and dibenzofurans arise. In the past, waste incineration was made causally responsible for the spread of the latter substances in the environment, however, the Federal Environment Ministry said in a press release in 2005 that this statement is no longer up to date ( " Kamen in 1990 one third of all dioxin emissions from waste incinerators, there were 2000, less than 1% "). However, criticism of this view was loud because the exhaust gas measurements at waste incineration plants supposedly make a systematic error: Dioxin is hydrophobic, and as much water vapor contained in the exhaust gases, the dioxin molecules pushing on the mitausgestoßenen dust particles. However, will only measured the concentration of dioxins in the air. This was the opposite, that the pollutants would be measured by including all particles discharged regularly flue gas sample, and then the substances present can be determined. The exact number and variety of resulting in waste incineration and released from their pollutants is not known. Limits, there are only 40 known airborne pollutants. The danger is that many different substances are present in the incineration of waste. Due to the large number of substances the dangerousness of individual occurring only in trace compounds can hardly be determined. The inhomogeneous waste fractions lead to the composition of the flue gas can change very quickly.

For waste incineration plants in Germany, the Federal Pollution Control Act ( Federal Pollution Control Act ) and its regulations apply. Specifically, the Regulation on the incineration and co-incineration of waste ( in short: 17 BlmSchV ) contains special requirements for the design of the furnace and are the limit values ​​for permissible emissions ago. The emissions must be continuously monitored and the measurement results are transferred online to the competent authorities. The 17th BlmSchV called in § 5 and Appendix addition to the limits and associated calculation methods for the assessment of emissions. Since the entry into force of the European Incineration Directive apply to waste incineration and co-incineration plants ( such as power plants, cement plants ) the same emission limit values ​​and the 17 BlmSchV had to be revised accordingly. Nevertheless, the legal equality and the fundamental advantages and disadvantages of the refuse use of a controversial debate in co-incineration of proponents and opponents, which among other things, LCAs are used for evaluation.

Ash, slag and dust

The solid residues from an incineration plant, about 30 % of the quantity of waste incinerated include ash and slag from waste incineration and waste from flue gas purification and waste water treatment and filter dust. During the combustion process, the exhaust gas cleaning and steam generation produced a series of solid end products from which slag has the largest share. 2002 were produced in the German waste incineration plants approximately 3.4 million tons of slag, which still remain after the slag processing 2.9 million tons. The slag is landfilled, used to fill abandoned mines or used as building material for dams and roads. A contingent liability boiler and fly ash, which are also disposed of in landfills or in closed mines. In addition, scrap iron and non-ferrous metals are sorted and recovered gypsum.

In Austria the maximum treatment capacity of the large waste incineration installations for the incineration of municipal waste and the waste fuel by the end of 2004 was around 1.6 million tonnes / year. 2003 fell from the incineration of municipal waste ( without installations for the incineration of hazardous waste ) around 190,000 t / year of bottom ash ( slag) and 88,000 t / year of fly ash. These amounts are expected by the year 2010 to around 314,000 t / year of bottom ash ( slag) and 170,000 t / year increase fly ash.

In Austria is deposited above ground or below ground because of the multitude of pollutants a large amount of slags and filter dusts.

In Germany, filter dust and the dried residues from flue gas cleaning chemical can be stored almost exclusively in salt mines. The incineration slag with the concentrated pollutants are deposited partly, but more commonly used as a filler in salt domes and in road construction. The MVA slags used in road construction are subjected to an eluate test, in which, however, only a few pollutants are examined.

In Switzerland, the slag is stored underground. Quenched slag from waste incineration plants is also used as sealing layer for the closure and reclamation of landfill surfaces. The filter dust is exported to Germany.

Built incinerators in German-speaking

Germany

According to the legal requirements of Krw-/AbfG in Germany may only waste for disposal, which can not be recycled or treated in an environmentally compatible in other ways, are given in the rest of incineration. The despite the separate collection and collection to be incurred House residual waste quantities and trade waste, these include.

The first waste incineration plant in Germany was built in 1893 at the Hamburg Bullerdeich. 1894 began trial operation, 1896, the regular operation started. The first Munich plant was built around the turn of the century, Berlin's first plant in 1921. Schöneberg However, the incinerator could not meet, why waste incineration in Berlin established after the Second World War, the hopes placed in it.

By 1998, 53 incinerators were built in Germany. The number rose to 2003 at 61. At that time it was planned to build another 15 facilities, mainly in East Germany ( then a total of 76). The Federal Environmental Agency published on its website a list (as of December 2009). These are called 69 German incinerators that burn municipal waste mainly.

Since 1 June 2005 untreated residual waste may not be disposed of in landfills. For a while the prices for the disposal of mixed waste and residual rose sharply. Therefore, many systems have been built from private economic interest. These plants burn mostly mixed commercial waste (see also substitute fuel power plant). Later, the disposal prices fell again; it became apparent that there is overcapacity in incinerators. A predictive study of 2009 written on behalf of BUND, threats to material recycling looks through this overcapacity. "Today, two million tons of waste are more waste imported than exported to Germany. This amount corresponds to the capacity of four large incinerators or waste -laden freight train of 1000 km in length. " However, at least since the year 2011, the situation seems to have relaxed again.

Switzerland

In Switzerland there are about 30 municipal solid waste incinerators ( MSWI ). In the Italian-speaking canton of Ticino was missing for a long time a plant, so the waste has either been moved to other cantons or temporarily deposited. In Giubiasco a new plant was built and commissioned in 2009. Since 2000, municipal waste in Switzerland may no longer be landfilled, but must be burned mandatory. " 5.5 million tonnes fall in Switzerland every year - every second 174 kg. This yields 709 kg per person per year. Half of it is recycled. "

Austria

In the capital, Vienna, there are currently four large incinerators: Incinerator Flötzersteig (1964 ), incinerator spittelau (1971 ), Pfaffenau waste incineration plant (2008) and with the work Simmer Haide (formerly at the disposal companies Simmering duly, 1980) a sewage sludge and hazardous waste incinerator. The district operated by Wien GmbH plants produce annually alongside around 116 GWh of electrical energy around 1,220 GWh of district heating, with 550,000 tons of household waste, sewage sludge and 180,000 t 90,000 t of waste are burned. This produces 190,000 tonnes of ash, slag, scrap and filter cake. Other facilities are located in Wels ( 1973), Duernrohr (2004), Lenzing ( 1998), Niklas village (2003) and Arnold Stein ( 2004).

Also in Austria, further investments are planned and created due to the coming into force on 1 January 2009 landfill ban for untreated residual waste.

South Tyrol

In Bolzano is the only incinerator in South Tyrol. In July 2013 a new, larger waste recycling plant was put into operation, generates the energy and district heating for up to 20,000 households.

Alternatives to Incineration

The easiest and best alternative to incineration is to be incurred as little waste as possible. This is done by reducing the amount of waste ( waste prevention ) and by the separate collection of waste produced yet, so they can be recycled.

In a recycling eg unmixed present in the waste materials recycled into new products can be produced. Since the purity is given especially in plastics from municipal solid waste only in rare cases is done here either a " down-cycled " into products with lower material requirements or material recycling after procedural treatment. In a sustainable circular economy therefore not recyclable waste as possible to avoid already in production.

For the purposes of the Kyoto Protocol are to conserve resources to techniques that conserve raw materials or utilize this sense a material flow management. After the exhaustion of the potential for waste prevention and material recycling can, a transitional thermal utilization of appropriately sorted municipal solid waste as a substitute fuel for fossil raw materials are used, for example in the cement industry or the production of steel, where the shredder light fraction from automobile recycling substituted as a reducing agent to the coal coke. However, this requires appropriate flue gas cleaning plants.

Since waste in Germany could be dumped untreated only until May 31, 2005, more waste treatment facilities must be built. There are several other methods for waste treatment, such as the cold waste treatment technologies that have been approved by the federal government as equal treatment plants instead of incineration. These have a much higher acceptance in the population as waste incinerators, which is probably also the fact that an expensive system of higher technical complexity (such as an incinerator with an integrated emission control ) triggers on a subjective evaluation more uncertainty than for example a biological composting system.