Incineration & landfilling

Håkan Jönsson Department of Energy and Technology

Incineration & landfilling

Håkan JönssonProfessor

[email protected] University of Agricultural

Sciences


Waste incineration

•Renewable fuel: 80-90% of Swedish household waste is renewable (incineration tax assumed 87.4%)

•Heating value: 2,5-3,2-4 kWh/kg, 9-11,5-14 MJ/kg

•Heterogeneous ”dirty” fuel–Extensive flue gas cleaning necessary

–Large plants

•Storage needed but difficult–Even production over the year

–Difficult when biowaste is included


Waste incineration 2008

– 29 incineration plants for household waste, 4.6 Mton/yr, of which 2.3 Mton/yr household waste

• Sizes; > 200 000/yr 7 plants (Sthlm, Gbg, Lin, Mö, Stje, Svall, Ua), 100 000 - 200 000/yr 4 plants and <100 000/yr 18 plants

– Energy recovery 12.2 TWh heat (29% of district heating) & 1.5 TWh electricity (1% of electricity use)

– Mass decreases by 75%, volume by 90%.• Residues: slag 20%, fly ash 3-5% (hazardous waste)• Initially introduced for mass and volume reduction


Air emissions

Substance 1985 1996 2002 2005 2008 Reduction85-08

Particles,ton 420 33 35 39 30 93%

HCl, ton 8400 412 143 98 39 100%

SOx, ton 3400 1121 790 310 154 95%

NOx, ton 3400 1463 1815 1904 2190 35%

Hg, kg 3300 77 21 33 44 99%

Cd, kg 400 8 15 (Cd+Tl)

21 (Cd+Tl)

6 (Cd+Tl)

>98%

Pb, kg 25 000 214 138 77 136 99%

Dioxins, g 90 2 1.1 1.1 0,8 99%


GRAABS plant, Gothenburg


Waste incinerator - Uganda


An advanced incineration system

Fig: Persson, 2005


Flue gas - pollutants• Particles

– Filter – electrostatic and/or textile filters

• NOx Fee 50 SEK/kg NOx (Total 688 milj SEK)– Ammonia injection:

4 NH3 + 6 NO -> 5 N2 + 6 H2O; 4 NH3 + 4 NO +O2 -> 4 N2 + 6 H2O – In furnace SNCR (Selctive Non-Cathalytic Reduction – 900-1050°C, 40-60%

reduction)– After furnace SCR (Selective Cathalytic Reduction – 300-400°C, 70-90%

reduction)

• HCl– Alkaline treatment (lime)

• SOx– Alkaline treatment (lime)

• Heavy metals– Removed with particles and acids

• Dioxin– Attaches to active C, removed with particles at low temperature


Flue gas cleaning - filters

• Cyclone• Electro filter• Textile filter

(slangfilter)• Scrubber

Ill: Niro A/S


Important parameters

• Temperature

• Retention time

• Oxygen

• Turbulence

Fig: Persson, 2005


Sources of dioxin in Sweden

Fig: Persson, 2005


Incineration plants

• Grate furnaces (Rosterpannor)– Most common– accepts large “particles” – sensitive for varying energy content – hard to control – much fuel in system– grates need water cooling if waste is dry

• Fluidised bed roaster (Fluidbäddpanna)– Easier to control and

adjust to fuel– Shreading necessary

- (max 10 cm)

Ill: Berman & Dille, Westinghouse

Fluidised bed roaster


A modern incineration plant

Fig: Persson, 2005


Flue gas cleaning

Fig: Persson, 2005


Incineration hazardous waste

Fig: Persson, 2005


Landfill


The different stages of a landfill

Fig: Persson, 2005


Water flows

Fig: Persson, 2005


Land fill and water flows

Fig: Persson, 2005


Requirements on liner

Tid Flöde

200 år <5 l/m2, år

50 år <50 l/m2, år

1 år

Fig: Persson, 2005


Hydrological considerations

Fig: Persson, 2005


Collection of landfill gas2003: 414 GWh to district heating, 26 WGWh electricity and 60 GWh not used.

Fig: Persson, 2005


A well managed sanitary landfill

Fig: Persson, 2005


Top and bottom liner

Fig: Persson, 2005


Liners - hazardous waste

Fig: Persson, 2005


Landfill –biowaste banned

• EU Directive fully implemented 2008

• Containment of waste• Biowaste goes anaerobic• Org C -> CH4 & CO2

– Greenhouse gas, 50% collected (optimistic figure), 10% oxidised

– Risk of fire

• Sinking – top liner damaged – more leachate• Nutrients and heavy metals leaches

Aim: totally sealed

Documents

Incineration & landfilling