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Plasma Gasification of Municipal Solid Waste

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by

Simrin Desai

on 3 December 2013

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Transcript of Plasma Gasification of Municipal Solid Waste

Plasma Gasification of Municipal Solid Waste (MSW)
GASIFICATION
PLASMA TORCHES
Te and Tg converge as P increases
Synthetic Gas
Vitrified Inorganics
GASIFIERS
TORCH POWER SUPPLIES
RF
AC
DC
TRANSFERRED
NON-TRANSFERRED
DESIGN SPECIFICS FOR PLASMA TORCHES IN WASTE TREATMENT
CURRENT RESEARCH
Produced from
inorganic
waste components
Produced from the
organic
waste components
MSW
LANDFILL
INCINERATION
HEAT SOURCES
GASIFIER CONFIGURATIONS
PYROLYSIS
ANATOMY
CHARACTERISTICS
Large quantity

Low contaminants

Elementary analysis
C H O Cl S F Ash and H2O

Macro Analysis
Organic, halogen and inorganic
COMPARISON
High energy densities and high temperatures

Use of electricity as the energy source
WHY PLASMA?
Increasing amount of O2
Source: Helsen, 2010
(Syngas)
SYNGAS USES
waste suspension
high reaction rate
short residence time
low quality syngas
cocurrent
low efficiencies
long residence times
high quality syngas
countercurrent
high efficiency
short residence times
low quality syngas
THERMAL PLASMA
Some Uses
+ Prevents electrode erosion
- Low efficiencies (40-70%)
Arc Plasma Torches
Cathode:
Thermionic emission

Needs to emit electrons without melting - Tungsten commonly used

Torch life related to cathode erosion

Anode:
Copper commonly used
Preheating/Drying Region ~ 300C
Gasification Region ~ 300-1000C
Combustion Region ~ 1000-1700C
Fusion Region ~ 1700-1800C
Waste passes through 4 regions from top to bottom...
Autothermal
Allothermal
Material
within
the reactor is combusted using air and/or O2
Heat source is
external
to the reactor
WASTE
EXAMPLES
Heat is inductively coupled into the plasma gas through induction coils surrounding the torch.
High heat transfer efficiency

Used in etching, welding, metallurgy
Flow of plasma jet inside a non-transferred torch. (Trelles et al.)
Used in spraying, and processing high T medium
Lower heat transfer efficiencies, but high jet velocities
Millions of Tonnes of Waste Produced in Canada
(Trelles et al.)
Source: EPA
Most commonly used in waste gasification units
WHY GASIFICATION ?
- Quicker electrode erosion - Shorter lifespan
Smaller gas volume

Capture of inorganic waste

Small aggregates

Applications for products
+ Can process large volumes
ELECTRODES
PLASMA GAS
Air - most commonly used

Oxygen, steam

Argon
Arc stabilization through cooling channels and rotating anode shell
(Hlina et al., 2013)
ORGANIC WASTE BREAKDOWN
Source: Arena, 2002
3-phase air-steam plasma torch,
designed for gasifying plastic waste. Steam helps the catalytic conversion of tars (Rutberg, 2013)
INTO THE FUTURE
ENVIRONMENTALLY SAFE
Reduced inorganic waste
Less off-gas to be treated
ECONOMICAL
"Waste Recovery", instead of disposal
Geographically dependent
ARC OPTIMIZATION
ELECTRICALLY POWERED
ELECTRODE PROTECTION
Electricity allows for flexibility
SAFE
Stability
Heat Transfer
High pressure
Not as mature of a technology as incineration
Implementing arc boundary conditions using:

Water cooling channels

Adding inert gas
Optimized by increasing the arc's intensity using:
Higher plasma jet velocities
Smaller nozzle size
Higher operating pressure
Changing flow pattern of gas

External magnetic coils
Mixing plasma gases

Insulation between electrodes
Source: Camacho, 1988
Source: Leal-Quiros, 2004
Source: Camacho, 1988
By Simrin Desai and Selina Liu
CO2 Emissions of Various Waste Treatment Solution
PLASMA-AIDED:
Source: Westinghouse
Source: Plasco
Advantageous Characteristics:
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