SECTION V: COMPLEMENTARITY OF WASTE-TO-ENERGY IN A WASTE MANAGEMENT SYSTEM “TMB and incineration in a waste management system: experience in Germany” by Mr. Stephanie Thiel, VIVIS Consult, Germany

1. Mechanical‐Biological Treatment (MBT) and
incineration in a waste management system:
experience in Germany
Dr.‐Ing. Stephanie Thiel
Professor Dr. Dr. h. c. Karl J. Thomé‐Kozmiensky
vivis Consult GmbH
Dorfstraße 51
D ‐ 16816 Nietwerder
Tel.: +49 3391 4545 0
Fax: +49 3391 4545 10
E‐Mail: tkverlag@vivis.de
RECUWATT Conference – Recycling and Energy, 25th March 2011
Outline
1. Introduction
2. Incineration of residual waste
2.1. Status quo in Germany
2.2. Technology of waste incineration
2.3. Problems and subjects of optimisation
3. Mechanical‐biological treatment of residual waste
3.1. Status quo in Germany
3.2. Technology of mechanical‐biological waste treatment
3.3. Technical, economic and ecological problems
3.4. Output streams and mass balances
4. Conclusions and Summary
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2. Waste Management System
– simplified illustration for household and commercial waste –
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Outline
1. Introduction
2. Incineration of residual waste
2.1. Status quo in Germany
2.2. Technology of waste incineration
2.3. Problems and subjects of optimisation
3. Mechanical‐biological treatment of residual waste
3.1. Status quo in Germany
3.2. Technology of mechanical‐biological waste treatment
3.3. Technical, economic and ecological problems
3.4. Output streams and mass balances
4. Conclusions and Summary
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3. Thermal treatment of mixed
municipal waste in Germany
Number of plants and their
capacity
• 67 Waste incineration plants
• 1 Pyrolysis plant
Total
68 plants
about 19 million t/a
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Grate furnace with a post‐combustion chamber
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4. Example of a waste incineration plant
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Reduction in emissions of pollutants from WIPs
Basis of data: Federal Ministry for the Environment, Nature Conservation and Reactor Safety, 2008
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5. Problems posed by the incineration of waste
and subjects of optimisation
• corrosion in the steam generator
Corrosion damage on a tube wall Weld‐cladding of a tube wall Superheater tubes with cladding
Source: CheMin GmbH Source: Uhlig Rohrbogen GmbH Source: CheMin GmbH
• fouling of the heating surfaces
• reduction of nitrogen oxides – selective non catalytic reduction (SNCR)
• availability
• waste throughput
• energy efficiency
• economic efficiency
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Outline
1. Introduction
2. Incineration of residual waste
2.1. Status quo in Germany
2.2. Technology of waste incineration
2.3. Problems and subjects of optimisation
3. Mechanical‐biological treatment of residual waste
3.1. Status quo in Germany
3.2. Technology of mechanical‐biological waste treatment
3.3. Technical, economic and ecological problems
3.4. Output streams and mass balances
4. Conclusions and Summary
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6. Mechanical(‐biological)
waste treatment plants
in Germany
61 M(B)T plants
Plant throughputs:
25,000 – 300,000 t/a
Total capacity:
6.4 million t/a
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Material Stream Separation
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7. Process flowsheet
Mechanical Processing of the BMA Dresden
minimum basic equipment:
• comminution
• screening
• magnetic separation
further possible aggregates:
• air classification
• ballistic separation
• eddy current separation
• near‐infrared spectroscopy (NIR sorting)
• x‐ray sensors
• colour sensors in the range of visible light
• hard material separation
• long parts separation
• manual sorting
• thermal drying
• pelletization
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Biological Treatment
• intensive and secondary
rotting
• biological drying
• fermentation
– and secondary rotting
– and aeration of the digestate
• percolation process
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8. Flue Gas Purification
• dust filter
• biofilter
• acid scrubber
• Regenerative Thermal Oxidation (RTO)
left:
acid scrubber
right:
RTO
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Problems posed by the
mechanical‐biological treatment of waste I
Mechanical processing
• High level of wear, tear and energy requirement
with processing and conveying aggregates,
e.g. comminution, pelletization
• Blockages and contamination,
e.g. during screening and ballistic separation
• increased time and effort for cleaning, maintenance and repairs,
thereby reduction of time availability and throughput
• Personnel requirement often significantly underestimated
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9. Problems posed by the
mechanical‐biological treatment of waste II
Fermentation
• At 5 plants operating with wet fermentation and aeration of the digestate in
sludge activation tanks, partly serious operational errors occurred during the
commissioning, including deflagration/fire and bursting of a fermentation reactor
• strongly fluctuating Typical production of gas in the MBT Ha nnover plant – smoothed waveform
production of biogas
due to discontinuous
substrate‐entry
• waste water:
possibility of high amount,
complex and very costly
treatment is necessary
Source: Vielhabe r, B.; Nülle, C. (2008), revised.
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Problems posed by the
mechanical‐biological treatment of waste III
Flue Gas Purification – Regenerative Thermal Oxidation (RTO)
• blocking of the ceramic honeycomb structure through siloxanes in the flue gas
• dimensioning frequently too small and lacking redundancy
• corrosion in the casing of the RTO and the gas pipes
• energy requirement frequently underestimated
Landfill fraction
• The landfill fractions from MBT have a higher organic proportion, and therefore
a higher biological activity than ash/slag from waste incineration plants
Methane emissions (climate‐damaging)
increased mobilisation of pollutants such as heavy metals
• It was not possible to comply with the assignment criteria specified for the
landfilling of ash/slag from waste incineration plants
less strict criteria were defined for landfilling of secondary waste from MBT
Corrosion
• e.g. buildings, ventilation system of the rotting system, RTO
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10. Costs
The waste disposal costs with MBT plants are similar to
those with waste incineration plants
They comprise the costs for
• construction and operation of the MBT plant
• combustion of solid recovered fuel (SRF) and further
combustible fractions for waste incineration plants (WIP)
• landfilling of the landfill fractions
• transports
Waste disposal costs for municipal solid waste
in Germany: approximately 100 Euro per ton
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False reasoning:
Reality:
in every MBT plant
solid recovered fuel solid recovered fuel
is produced power stations
intermediate
storage
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11. Comparison of the systems of MBT and WIP
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Mass balance of M(B)T plants
throughout Germany
estimation, 11/2007
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12. Outline
1. Introduction
2. Incineration of residual waste
2.1. Status quo in Germany
2.2. Technology of waste incineration
2.3. Problems and subjects of optimisation
3. Mechanical‐biological treatment of residual waste
3.1. Status quo in Germany
3.2. Technology of mechanical‐biological waste treatment
3.3. Technical, economic and ecological problems
3.4. Output streams and mass balances
4. Conclusions and Summary
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Conclusions and Summary – Incineration
• the most developed residual waste treatment process
• ideal combination of waste treatment and energy supply
(electricity, process heat, district heating and/or remote cooling)
• combined heat and power generation is pre‐condition for high
energy efficiency
• pollutant sink for harmful substances in waste
• emissions of pollutants: dramatic fall in comparison with the
period prior to 1990 – clear undercut of the limit values on annual
average
• problem of corrosion – solutions for reduction are disposable
• availability, energy efficiency and economic efficiency are further
optimised in several plants
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13. Conclusions and Summary – Mechanical‐biological treatment
• MBTs are complex waste treatment plants with a wide ranging
variety of technical configurations
• various technical, economic and ecological problems,
partly solved and partly still subject of optimisation
• MBT cannot replace waste incineration
– MBT is only a pre‐treatment of waste prior to its incineration
• incineration is simply delayed – more complex system
with more material streams and treatment steps
• altogether in Germany almost 60 wt % of the waste input
of MBTs finally are incinerated
• in Germany waste disposal costs with MBTs and WIPs are similar
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Reserve‐Folien
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14. ENERGY CONVERSION THROUGH WASTE
INCINERATION IN GERMANY
Evaluation of 64 of 68 plants
for the thermal treatment of municipal waste
44 plants: both electrical power as well as heat
(as district heat or steam) Combined heat and power
9 plants: electrical power only
9 plants: Provision of steam to an external user (full)
(generally to a power station or a combined heat and power plant)
2 plants: district heat only
CONTRIBUTION OF WASTE INCINERATION TO THE SUPPLY OF ENERGY
19 million t of waste are incinerated in Germany:
~ 5 million MWh electricity
~ 15 million MWh district heat
Energy efficiency
Measures to increase energy efficiency – examples
• combined heat and power generation
• heat utilisation as process heat, district heating, remote cooling
(examples: Wien, Kassel)
• reduction of the flue gas temperature
• reduction of the flue gas volume
• elevation of the live steam temperature and pressure
• reheating
• preheating of secondary air
• preheating of condensate
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15. Energy efficiency
Technical/scientific definition Attainable net efficiency
net energy efficiency (depending on the individual basic conditions):
• pure electricity generation: up to > 30 %
• concurrent generation of electricity and
district heating/process heat:
overall efficiency: 70‐80 %
• pure generation of process heat: up to > 90
Political definition %
gross energy efficiency
assessed by the R1 formula
– range of german WIPs
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Mechanical‐Biological Stabilization
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16. Mechanical‐Physical Stabilization
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Mechanical(‐Biological) Pre‐Treatment
prior to Incineration
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17. 33
Processes for the purification
of waste water (simplified)
Source: Schalk, P. (2003)
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18. In case of a planned opening of the plants that are currently under
construction
– Projects are not considered–
End of 2011
presumably:
36 plants
4.81 million t/a
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Mass balances of exemplary M(B)T plants
with production of high‐quality SRF
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