Tar Production and Destruction - Biomass Gasification, Pyrolysis and Torrefaction - page 181

25

20

15

10

5

0

0 200 400 600 800 1000 1200 1400

Temperature (°C)

FIGURE 6.1 Effect of maximum gasification temperature on the range of tar yield. Source:
From Baker et al. (1988).

1

0.8

0.6

0.4

0.2

0

500 550 600 650 700 750 800 850 900 950 1000

Temperature (°C)

Primary Secondary Tertiary-Alkyl Tertiary-PNA

FIGURE 6.2 Variation of primary, secondary and tertiary tar products with temperature for
0.3 s residence time. Source: From Evans and Milne (1997), p. 807.

6.2.3 Tar Composition
As we can see in Table 6.3 , tar is a mixture of various hydrocarbons. It may
also contain oxygen-containing compounds, derivatives of phenol, guaiacol,
veratrol, syringol, free fatty acids, and esters of fatty acids (Razvigorova
et al., 1994). The yield and composition of tar depend on the reaction