BIOMASS COMPOSITION, PROPERTIES, AND CHARACTERIZATION - Biomass as a Sustainable Energy Source for the Future - page 64

2.3 Chitin is a biopolymer containing nitrogen in its structure. What is the weight

percentage of N in chitin?

2.4 Table 2.3 shows the fuel composition of different biomass species; calculate

the molar S to Cl ratio for olive cake pellets and sunflower residue. What
possible consequences could the difference have in the combustion of
these fuels?

2.5 What is the nitrogen content of pepper plant residue on a mg per MJ basis
(HHV, as received fuel)?

2.6 A company exists that has developed a toilet in which the feces are burned.

Consider the composition of feces to be as follows (dry basis):

C = 43.0 wt%; H = 6.3 wt%; O = 35.9 wt%; N = 2.3 wt%; ash = 12.5 wt%.

The moisture content of the material is 71 wt%.

a. What is the HHV on a dry basis (in MJ

“ as received ”

kg −1 )?

kg −1 )? b. What is the LHV on an “ as received ” basis (in MJ

kg −1 material as received) is needed to exactly com-
pletely combust the material? Assume NO to be the combustion product of
N in the fuel.
d. In practice, would one use exactly this amount of air? Why (not)?

c. How much air (in kg

MJ −1 (HHV basis)

For the following fuels, calculate the emission of CO 2 in g

2.7

for complete stoichiometric combustion:

￿ Wood pellets

￿ Peat

￿ Brown coal

￿ Bituminous coal

Which fuel gives the highest value?

kg −1 (db), what is the LHV (ar) when the
moisture content (ar) is 15 wt% and the ash content is 0.8 wt% (db)?

2.8 A woody fuel has an HHV of 19 MJ

2.9 Search the literature for ash fusion temperature data related to straw; would it

make sense to wash the straw with water and why (not)?

2.10 If the thermal input on an LHV basis of a straw-fired combustor is 10 MW th ,
what is the amount of CO 2 emitted in t year −1 in case of complete combustion

of the fuel? What could be the net CO 2 savings when this thermal input replaces
coal, also assuming complete combustion? Is the calculation really an exact
reflection of the CO 2 savings?
2.11 An ash analysis of all the ashes discharged from a waste wood-fired thermal
conversion plant revealed that this plant produces ash with a lead (Pb) content
of 100 mg kg −1 . What is the Pb content of the original fuel on a dry basis (db)