Page 198 - Energy from Toxic Organic Waste for Heat and Power Generation

176 Energy from Toxic Organic Waste for Heat and Power Generation

11.7.1 Production of Fuel Oil From LDPE
11.7.1.1 Effect of Temperature on Thermal Conversion
Fig. 11.15 presents changes in mass of LDPE observed with increase in
temperature. Increase in temperature resulted in significant weight loss
of LDPE under a linear heating rate. Results showed maximum weight
loss of LDPE when the temperature approached near to 400°C. However,
weight loss caused by volatilization of hydrocarbons mainly depends on the
composition of polyethylene. Investigation showed that maximum weight
loss (99.96%) occurred when temperature changes from 170°C to 420°C.
Residue or carboneous material of 0.4% has been observed when tempera-
ture was above 420°C caused by decomposition of polyethylene. Further,
in continuation with volatilization process, cracking of side chains from
aromatic rings, isomerization, and polycondensation also occurs. This study
shows that polyethylene decomposition resulted into volatile hydrocarbons.
Effect of temperature on thermal degradation of LDPE is presented in
Fig. 11.16. The degradation of LDPE resulted in different products such as
liquid oil, gases, and solid residue. It is found that as the degradation tem-
perature increases, conversion of LDPE to gas and liquid fraction occurs.
Maximum of 56.2% liquid oil and 41.6% gas conversion has been observed
when temperature was increased above 420°C.

11.7.1.2 Effect of Temperature on Catalytic Conversion
Fig. 11.17 presents the effect of temperature on catalytic degradation of
LDPE. The products obtained include liquid oil, gases, and solid residue.
Conversion of LDPE into oil and gas increased when the reaction was carried
out with catalyst. To investigate suitable temperature for catalytic degradation

100

80
Weight (%) 60

40

20
0
0 100 200 300 400 500 600 700
Temperature (°C)
Fig. 11.15 TGA curve of waste LDPE.