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14/06/2011

US Patent Issued to BEG on Feb. 1 for "Integrated Process for Waste Treatment by Pyrolysis and Related Plant" (Italian Inventors)

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Energy from Waste (Pyrolisis)   Main benefits | Plants | Photo gallery

Urban and special waste disposal and energetic coal powder recovery plant in Hamm, Cologne (Germany)

The Hamm plant - owned by the German power producer RWE and made by Manesmann and Technip – is an integrated facility, where the pyrolisis section is integrated within a coal powder recovery plant for the production of electric power.
Coal produced by pyrolisis is mixed with fossil coal and sent to the burners, in order to produce hot steamt, hat is subsequently sent to a turbine.

 
     

General description of the plant

The plant (made up of three lines – A and B built in 1963, and C in 1969 – with a 500 MW producibility) is powered by hard coal from the nearby Ruhr area but also from Eastern Europe, Australia, South America and South Africa.
The coal storage area, with its 180.000 tons, assures more than a month of efficiency.

 
     

Description of the coal powder recovery section

The coal powder needed by the burners is obtained through the grinding of hard coal, which is subsequently sent into the combustion room, where the water flowing into the pipes evaporates
at  1500 °C.
The steam produced in this process – with a pressure between 180 and 215 bar and a temperature of 550°C – is sent into a multistage turbine for the production of electric power.

 
     

Pyrolisis section

This integrated section, built at the end of 2001, is used for the energetic recovery of new combustible, such as urban solid waste or its fractions (SFR - Solid Recovered Fuels).

 
     
The incoming waste is storaged in a special area and then loaded on a conveyer belt towards two pyrolisis cylinders.
These cylinders (also called rotary kiln) are heated through the combustion of natural gas or through hot gas pumped from the syngas combustion chamber.

 
   

Waste coming from the rotary kilns (120.000 tons per year, 60.000 tons for each kiln) are pyrolised and converted in two fractions: a light gaseous one (pyrolisis gas) and a solid one, consisting of coal.
The resulting gas is sent to the combustion chamber after being depulverised through specific electrostatic turbines.

 
Analysis – Characteristics of pyrolisis gas at 20°C
Hydrogen 15%
Carbon monoxide 20%
Carbon dioxide 39%
Methane 12%
Hydrocarbons 13%
Produced gas 700 /t of waste
Calorific power 10000-14000 KJ/
Density 0,8-1,2 Kg/
   
     

All the produced coal is discharged in the waste extinguishment section, and then sent on conveyer belts (equipped with permanent magnets in order to separate metals) through screwpumps.
After that, the produced pyrolisis coke is mixed with hard coal.
In this way, the use of fossil combustible is minimized, just as the production of carbon dioxide.



 
Analysis – Characteristics of pyrolisis coke
- Appearance /Color Black
- Odour Odourless
- Density 0,6 Kg/l
- Calorific power 8.600 KJ/Kg
- Quantity 300 Kg/t of waste
- Aluminium Oxide 11%
- Ethyl Silicate 39%
- Iron Oxide 5%
- Calcium Oxide 7%
- Carbon 26%
- Anions (Sulfates, Carbonates, etc) 10%
   
     

Urban, special and industrial waste processing plant in Burgau, Dortmund (Germany)

The Burgau plant, built more than 20 years ago, processes 35.000 tons per year of urban and industrial solid waste.
With its 150.000 hours of work, this plant is an example of the flexibility of supply and the performance consistency of pyrolisis.

 
     

General description of the facility

Burgau plant disposes of 35.000 ton per year of urban, industrial and special waste through two pyrolisis cylinders.
Waste pyrolisis takes place at a temperature of about 450-500 °C. Organic substances thermically decompose and form a gaseous combustible (pyrolisis gas) and a solid one (coal or pyrolisis coke).

Through  to this process, the weight of waste is reduced by 90% and its volume by 95%.

Thanks to a cogeneration facility, heat produced by controlled pyrolisis gas combustion is recovered and transformed into thermal and electric power.  The electric power, partially used for internal needs, is sold to the national power network distribution, while the thermal one is used for the heating of nearby buildings.
The working process is the same of the Hamm plant.

The main difference with the Hamm facility stands in the fumes depuration section, which is not, in Burgau, integrated in the plant.  Furthermore, to simplify the fumes depuration process, calcium hydroxide is mixed with every ton of input waste, in order to trigger off acid gas neutralization reactions inside the pyrolisis cylinder. About 60/80% of polluting gas, such as hydrocloric, sulphuric and hydrofluoric acid, react to the input lime inside the cylinder.

   
     
The fumes depuration section - extremely simplified, when compared to the traditional waste-to-energy facilities, thanks to the gas neutralisation process inside the pyrolisis cylinder - consists of a dry-reactor for the removal of mercury and other polluting substances through active carbon and  hydrated lime in a sleeved filter.
The filter holds absorption process dusts, salts resulting from neutralisation reactions and  the particulate already in the combustion fumes.
Through this simplified operation, the resulting exhaust gas emissions show values far below the limits consented by law (see table).
 
     
Differences between Pyrol-B facilities and the examined plants

The main difference between the afore-mentioned facilities and those built by Pyrol-B is in the
quantity of waste generated by the process.
The old pyrolisis systems generate a quantity of waste that equals 30% (in weight) of the input
waste (a smaller percentage of what a traditional waste-to-energy facility produces, I.E. about 50%).

The PYROL-B process, integrating the traditional pyrolisis systems with a C.R.T. section (a section
in which the produced coal is processed, with a subsequent production of combustible gas and inert
residual), allows to decrease the quantity of waste, that equals 10% of the input, and to increase the
quality of produced gas, benefiting the global efficiency of the process.


   



 

 

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