L10 - Thermal treatment of waste

what does incineration does to waste

remove pollutants and burns the flammable components

What is the leader in the EU in incineration? And how many incinerators do they have?

Switzerland, approx 70 incinerators

What is more constly - incineration or landfilling?

incineration

Name the processes during the process of incineration

Drying, Gasification, Ignition, Burnout

What temperatures must the incinerator be to ensure complete burnout for __***municipal waste***__?

850°C

What temperatures must the incinerator be to ensure complete burnout for __***hazardous waste***__?

1100°C

What is the moisture content when drying at 105°C?

15-35%

What is the moisture content of inorganic content when drying at 550°C?

10-25%

3 different modes of waste incineration process

1. Direct oxidative combustion
2. Pyrolysis
3. Plasma torch

What temperatures does a plasma torch have?

>4000°C

What are the 2 types of pre-treatment of waste?

1. Direct incineration (all flammable substances)
2. Refuse derived fuel (RDF) treatment (non-flammable part is removed)

What are the 3 types of design of the incineration kiln?

1. Moving grate
2. Rotary
3. Fluidised bed

What temperatures does the **moving grate** reach?

800-900°C

What is the moving grate generally used for?

Municipal waste

What temperatures does the **fluidised bed** reach?

650-1200°C

What temperatures does the **rotary kiln** reach?

up to 1500°C

What is the rotary kiln generally used for?

Hazardous waste, sludge

Is pyrolysis endo/exothermic

Endothermic

What temperatures does the **pyrolysis** reach?

above 430°

At what temperatures are off-gases treated in pyrolysis?

900-1300°C

Advantages of **moving grate** incineration?

Proven tech, large variety of wastes, large units available

Disadvantages of **moving grate** incineration?

Investment and maintanance are high

Advantages of **fluidised bed** incineration?

low content of CO, solid liquid and gas can be burned simultaneously, mixing doesnt allow cold spots

Disadvantages of **fluidised bed** incineration?

inert marerials difficult to remove

Advantages of **rotary kiln** incineration?

proven tech, regulation of speed, incinerating any waste, mixing of waste

Disadvantages of **rotary kiln** incineration?

high heat requirements, risk of damage

Advantages of **pyrolysis**?

its gas can be used as fuel, lower temperatures (maintenance, equipment), small scale

Disadvantages of **pyrolysis**?

construction materials costly, carcinogenic susbtances may be formed

What is gasification?

Conversion of carbon containing materials into gas (syngas), it is the continuation of the pyrolysis process

What temperatures does gasification happen at?

500-1800°C

Advantages of gasificaton

smaller volume of gas compared to combustion, less wastewater, predominant Co over CO2

Disadvantages of gasificaton

required granulated input

What are refuse derived fuels?

Fuel produced from different types of waste

Different types of exhaust gas cleaning systems

Dry, semi-dry, wet

What do emission dusts contain?

volatile heavy metals and organic compounds

How can acid-noxious gases be eliminated?

dry, semidry or wet techniques

How can NOx be removed?

SNCR (Selective non catalytic reduction), SCR (selective catalytic Reduction)

Temperature for SNCR process

850-1100°C (ideal 950°C)

Temperature for SCR process

350-400°C

How can heavy metals and dioxins be eliminated?

activated carbon, activated coke, activated carbon-lime mixtures

Process to remove heavy metals and dioxins

fly-flow adsorption, fixed-bed adsorption