to read the full report - Ecolateral by Peter Jones

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Evaluation of Opportunities for Converting Indigenous UK Wastes to Wastes and Energy
AEA/ED45551/Issue 1
of the synthesis package and so will be described below in that section. The requirements for the more
demanding end uses have been summarised by the Karlsruhe Institute of Technology. 278 .
Cleaning processes, especially those for the tars, have proved exceptionally difficult to design and
implement in practice and are the principal cause of project failure where engines and gas turbines are
used.
Options that have shown success are:
For tar removal
• Catalytic cracking or steam reforming on limestone or nickel catalysts. (VTT, Condens)
• Filtration on ceramic filter with limestone precoat. (Gussing, Biomass Engineering)
• Liquid scrubbing with vegetable oil or biodiesel. (Gussing, Xylowatt)
• Wet electrostatic precipitators (REFgas)
• Plasma reaction chamber. (Europlasma)
For dust removal
• Ceramic, or sintered metal filters (Guessing, Biomass Engineering)
• Cyclones
• Liquid scrubbers with vegetable oil or biodiesel. (Gussing, Xylowatt)
• Plasma reaction chamber. (Europlasma)
Table 78 Syngas trace contaminants and target levels in ppm 278
mg/Nm 3 Biomass
gasification
Gas motor Gas turbine MeOH FT (Sasol)
Particles 10 4 – 10 5 < 50 < 1 0.2 n.s.
Tar 0 – 20,000 < 100 < 5 < 1 n.s.
Alkali 0.5 – 5 n.s. < 0.2 < 0.2 < 0.01
NH3, HCN 200 – 2000 < 55 n.s. < 0.1 < 0.02
H2S, COS 50 – 100 < 1150 < 1 < 0.1 < 0.01
Halogens 0 – 300 n.s. < 1 < 0.1 < 0.01
Heavy
Metals
0.005 - 10 n.s. n.s. n.s. < 0.001
n.s = not specified
Gas conversion
The clean gas has many uses. It can be burned directly, to provide heat, raise steam, or drive electrical
generators. It can also be used as a feedstock for further processes to synthesise methane, diesel fuel
components and other chemicals and fuels.
Without doubt the most successful application to date has been the direct combustion of gas in industrial
processes and boilers.
The most quoted example of process use is the use of fluidised bed gasifiers producing low calorific gas
for heating lime kilns in the paper and pulp industry. Typically the gas is burned through a burner nozzle
designed for the low calorific value directly into the combustion chamber of the process unit. One unit in
Varo Sweden has been operating since 1987. 279
Gas can also be used to raise steam in a boiler which can in turn be used for power generation. This is a
robust concept that carries much less technical risk than the use of engines or gas turbines. Prime
examples of this are those processes based on an externally heated reactor with all the heat release in a
278 IEA Bioenergy Agreement Task 33 Spring 2009 Workshop, Karlsruhe, www.gastechnology.org/iea German country update
279 IEA Bioenergy Agreement Task 33 Spring 2009 Workshop, Karlsruhe, www.gastechnology.org/iea Swedish country update.