Torrefaction - Biomass Gasification, Pyrolysis and Torrefaction - page 142

M f mass of feedstock (kg)
M w mass of water in feedstock (kg)
M ash mass of ash in feedstock (kg)
M g mass of diluted hot gas per unit mass of oil burnt (kg)

M oil mass flow rate of oil burnt (kg/s)

Py Pyrolysis number ( )

Q energy content (kJ)

Q d theoretical heat load of dryer (kW)

Q 0 d actual heat load of dryer (kW)

Q t theoretical heat load of torrefier (kW)

Q 0 t actual heat load of torrefier (kW)

Q tl

heat loss from torrefier (kW)

r p radius of biomass particle (m)

external surface area of a biomass particle (m 2 )

S

T gi temperature of gas at inlet of torrefier plant ( C)

T 0 ambient temperature of gas, ( C)

T g0 temperature of gas at exit of torrefier plant ( C)

T t torrefaction temperature ( C)

U g space velocity of gas (m/s)

U s space velocity of solids (m/s)

volume of biomass particle (m 3 )

V

W d dry biomass feed rate (kg/s)

W f feed rate of wet or as-received biomass (kg/s)

W g flow rate of diluted hot gas entering the torrefier (kg/s)

W t production rate of torrefied biomass (kg/s)

X d fractional heat loss from the drier ( )

Subscripts
ar as-received basis

bulk bulk

cooler cooling section of torrefaction plant

d dryer

daf dry ash free basis

db dry basis

feed feedstock or raw/wet/as-received biomass

pd predrying section

pdh postdrying heater

t torrefied product

tor torrefier

product value in product

Greek symbol
ρ

density (kg/m 3 )

λ thermal conductivity of biomass (kJ/C m)

η combustion efficiency of burner ( )