3.2. Gasification study of 35 mm groundnut shell briquettes
An open core down draft gasifier having capacity of 50 kW was selected for gasification
studies of 35 mm groundnut shell briquettes. The gasifier consists of a well-insulated
cylindrical reactor with air nozzles and open top, manually operated rotating type cast iron
grate, an induced draft fan and nozzle type producer gas burner as the major components.
Initially 43 kg charcoal was loaded in the gasifier up to the air nozzles level. Thereafter
the gasifier was loaded with 133 kg groundnut shell briquettes. The gasifier operation was
initiated using suction of electrical blower. It takes around 15 min to generate flammable
gas, which was burnt using naturally aspirated nozzle type burner attached after the
electrical blower. The system was operated continuously for about 180 min without any
problems.
U tube manometer was used to measure the pressure drop across the gasifier. Digital
multi-channel temperature indicator with Cr–Al thermocouples was used to measure the
temperature profile. Calibrated orifice plate was used to determine the flow rate of
producer gas.
The gas flow rate was 182.81 m3
/h at 300 1C and 700 mm of W.G. pressure. The
variation of temperatures with time is shown in Fig. 3. The pressure drop across the
gasifier was 6 mm W.G. The flame temperature was consistent within the range of 869 to
929 1C. After stabilization of the operation a producer gas sample was collected by water
displacement method and it was analyzed with the help of a gas chromatograph. The
results are tabulated in Table 2.
Thus, the calorific value of the producer gas was 1144.54 kcal/m3 at 30 1C, which was
calculated from the above composition (HHV). No fuel flow problems were noticed during
the operation