Environmental Engineering Reference
In-Depth Information
2.10 Sugar extracted from sugar beets can be fermented to produce ethanol. Why is
this an example of a first-generation biofuel production process?
2.11 Why is Jatropha curcas -derived biodiesel sometimes called a
1.5-generation
biofuel?
2.12 Which elements in biomass do you expect to be most troublesome in thermal
conversion processes and in which respect?
2.13 Why is the procedure for the determination of the volatile matter content in the
proximate analysis different for biomass and coals?
2.14 In TGA analysis, hardwoods (e.g., birch, beech, and acacia) show the presence
of a
whereas this is less visible for softwoods (e.g., spruce).
What can be the reason for this difference?
shouldered peak,
2.15 In TGA analysis, nitrogen can be used as sweeping gas, but also helium might
be used. What is the main difference between these gases and why is helium
attractive to use?
2.16 What kind of correlation do you expect between the ignition temperature (e.g.,
in air) and the volatile matter (VM) content of biomass? Which other factors do
you think play a role in ignition?
2.17 What would be the consequence if in a burner designed for operation on a fuel
with a low VM/FC ratio (e.g., coal), this fuel were replaced by a fuel with a low
VM/FC ratio (e.g., biomass)?
2.18 Explain in your own words the difference between the HHV and LHV of a fuel.
2.19 Discuss the different ash fusion methods; do they represent well the phenom-
ena occurring in a fuel combustion reactor?
2.20 In which respects could biomass fuel blending be advantageous? Does it also
have disadvantages? Explain.
2.21 Certain plant species but also (modified) chitosan can take up some elements
very selectively and concentrate them. What are possible risks and opportu-
nities of this specific uptake behavior? See Dodson et al. (2012).
PROBLEMS
2.1
For physical and chemical processing, the specific surface area of a (solid)
fuel plays an important role. Now, if one wants to dry grass (blades) in a packed
bed with characteristic length ( l ), width ( w ), and thickness ( H ), what would
then be the specific surface area per m 3 of packed bed, a v ? Which dimension
would be most important for determining the value of a v and what do you
assume here?
2.2
In the Van Krevelen diagram (Figure 2.1), mark the position corresponding to
the composition of sunflower pellets.
 
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