Waste destructors can have extensive ash reuse in bricks and paving stones
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What is composition of UK MSW?
Paper/board make 33%, plastics 9%, glass 10%, metals 8%, food/garden 20%, textiles 4%, other 18%
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What are moisture, inert and combustible contents of MSW? How does energy compare to oil?
Moisture is 31.2w/w, combustibles 44.6 w/w, inert 24.2 w/w, calorific value of 10.6 MJ/kg. Calorific value of MSW is 1/3 of coal. I tonne MSW makes 200kg of oil.
Effective waste combustion needs time (combustion gases must stay at high temperature >2 seconds, at correct temperature, with turbulence (contact, oxygen and temp)
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What are EfW advantages?
No methane production, incineration close to where waste collected, EfW has track record in European countries. Produces ash with 1/10 volume and 1/3 weight of original waste. Emissions controlled and energy extracted from waste
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What are EfW disadvantages?
Generates CO2, public perception, high costs and long pay back, needs long term disposable contracts, needs high calorific wastes like paper/plastics. Concern over dioxins and furans emissions, ash residue needs disposalW
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How does Tees Valley Renewable Energy work?
In EfW plant, waste enters, is gasified with oxygen input and combustion. **** released, gas cleaned up with proprietary gas processing, before power production begins with gas driving turbine. Waste would otherwise be in landfill as nonrecyclable.
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What are gas plasma plants? (local plant)
Gas plasma plants more environmentally friendly. Converts waste to energy free from emissions. RDF is refuse derived fuel
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How is gas cleaned in gas plasma plant?
Waste enters gasifier, fuel drops on bed of sand which produces synthetic gas which exits top of gasifier to plasma converter. Cleaned by plasma and 1500 temp, clean gas then leaves converter. Gas enters cleaner to remove particulate matter.
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How does volcanic ash get used in plasma power waste plants?
Ash becomes plasma rock, the glass can then become a product.
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What are elements of EfW plant?
Unloading area/waste storage, crane (collects waste), hopper and waste feed system, combustion grate, furnace, air supply, boiler system, ash removal and flue glass cleaning system
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`How much waste do cranes gather?
Cranes typically grab 5 tonnes of waste. Waste then burns on the grate.
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How is metal extraction possible?
IBA (Incinerator bottom ash)discharge system allows for metal extraction
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What are products of MSW incineration?
Acid gases: HCl, CO2, NOX. Volatile metals: Pb, Zn, fly ash: particulate material, organics: include dioxins and furans, IBA: unburned materials/metals, heat energy to generate electricity onsite, CO2 emissions
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How are pollutants dealt with in EfW?
Pollutants collected in Air Pollution Control residues
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What are longer names for dioxins and furans? Why are they bad?
Polychlorinated dibenzodioxin (PCDD) and polychlorinated dibenzofuran (PCDF). Toxicity depends on number and position of Cl atoms. Can cause skin acne, digestive and neurological disorders, and muscle/joint pain
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What is biggest source of dioxins and furans
Open burning
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How does an incinerator bottom ash recycling plant work?
Ages raw ash passes magnet to collect ferrous and non ferrous materials. Then screened. < 8mm can be used as fines in concrete blocks 8-20mm can be used in cement and bound bituminous asphalt, >20mm used as coarse aggregate
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What is done with APC residues?
Air Pollution Control residues produced by cleaning gaseous emissions from waste incineration. Mix of lime which is used to neutralise acid, and carbon to remove dioxins and heavy metals, also fly ash. Fine particles removed with filters.
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Why are APCs harmful?
APC residues hazardous waste as high alkalinity, irritant, heavy metal content
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What are issues of APC?
Heavy metals, high alkalinity, dioxins/furans and high soluble salt content, leachable chloride (Cl-)
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What are options with APC waste? (remains big UK issue)
Hazardous waste landfill, solidification/stabilisation, long term salt mine storage, chemical treatment (reacting with waste acid), thermal treatment (vitrification)
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Other cards in this set
Card 2
Front
What is composition of UK MSW?
Back
Paper/board make 33%, plastics 9%, glass 10%, metals 8%, food/garden 20%, textiles 4%, other 18%
Card 3
Front
What are moisture, inert and combustible contents of MSW? How does energy compare to oil?
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