Page 163 - Biomass Gasification, Pyrolysis And Torrefaction Practical Design and Theory

140 Biomass Gasification, Pyrolysis and Torrefaction

Energy required for evaporation of the 30% moisture (Example 4.4) in bio-
mass in dryer section is calculated using Eq. (4.19):
Q dry 5 ð0:566 3 0:3Þ 3 2260 5 383:8kW
Energy required for heating 0.396 kg dried biomass (Example 4.4) to 280 C

is calculated using Eq. (4.19):
Q pd 5 0:396 3 0:269 3 ð280 100Þ 5 19:2kW
Total load 5 66.1 1 414.6 1 19.2 5 469.0 kW
So, Q total 5 469 kW

Burner Design Given:

T gi 5 300 C, T t 5 280 C, T g0 5 105 C, T 0 5 20 C

Theoretical (A/F) ratio 5 14.6
Burner efficiency, η 5 0.95; LHV oil 5 45,500 kJ/kg
The amount of flue gas, W g , fed into the torrefier is calculated using
Eq. (A.5) of Appendix:
A
W g 5
C g ðT gi 2 T g0 Þ
A 5 ðW v C v 1 W vl C g ÞT g0 1 W t C d T t 2 W f C b T 0 1 W v L

We use the data given below for calculation:
T gi 5 300 C; T t 5 280 C; T g0 5 105 C; L 5 2260 kJ=kg

Values calculated in Example 4.4 are as follows:
W t 5 0.277 kg/s
W v 5 0.170 kg/s
W vl 5 0.119 kg/s
W f 5 0.566 kg/s
A 5 (0.17 3 1.89 1 0.119 3 1.13) 3 105 1 0.277 3 0.269 3 280 0.567
3 1.46 3 20 1 0.17 3 2260 5 436.4 kg/s

A 436:4
W g 5 5 5 1:98 kg=s
C g ðT gi 2 T g0 Þ 1:13ð300 2 105Þ
0
W 5 W f 1 W g W t 5 0:566 1 1:98 0:277 5 2:27 kg=s
g
To find oil consumption, we use Eq. (A.7) of Appendix:
1 W g C g T gi
W oil 5 3 2 1
0
K 2 P W 0 C g T g0 1 VL LHV vl η
g fr