03.08.2015   Technologies for Converting Biomass to Useful Energy

GASIFICATION SYSTEMS

Flexible utilization of biomass or black liquor to useful products by means of gasification is carried out in more or less complex systems, including beside the gasifier a variety of upstream and downstream process components selected depending on the requirement of the application and also use of fuel. Examples of components in gasification systems are illustrated in Figure 6.5.

In the subsequent sections below different gasification as well as downstream process technologies are briefly described.

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•Chipping

• Fixed bed

•Tar reforming

• Gas turbine

• Sizing

• Fluidised bed

• Filtration

• Combined heat &

• Torrefaction

• Entrained flow

•Scrubbing

power

• Pyrolysis

• Gas cooling

• Fuel cells

•etc.

1 1

•WGS upgrading •etc.

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• Synfuel applications

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Upstream processing

Downstream processing

Figure 6.5. Different steps included in a gasification system.

Table 6.2. Comparison of the three fixed bed gasifier technologies

(adapted from Knoef, 2005).

Fuel (wood)

Updraft

Downdraft

Crossdraft

Moisture wet basis [%]

<60

<25

10-20

Dry-ash basis [%]

<25

<6

0.5-1.0

Ash melting temperature [°C]

>1000

>1250

Fuel size [mm]

5-100

20-100

5-20

Application range [MW]

2-30

1-2

Gas exit temperature [°C]

200-400

700

1250

Tar [g/Nm3]

30-150

4.5-5.0

4.0-4.5

Gas LHV [MJ/m3N]

5-6

85-90

75-90

Hot-gas efficiency [%]

90-95

3-4

2-3

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