**3.1 Feedstock and feedstock preparation**

Feedstock used in this study is PEFB collected from the palm oil mill in Chonburi province which is located in Eastern part of Thailand. After collecting process, PEFB is prepared before being used as feedstock. The important properties of solid fuel for using as feedstock in gasification process are proximate analysis, ultimate analysis, bulk density and heating value as shown in Table 7. The proximate analysis was determined according to ASTM D 5142, the ultimate analysis, e.g. carbon, hydrogen and nitrogen was investigated using ASTM D 5373 and sulfur containing in PEFB was analyzed by ASTM D 4239 (Miller & Tillman, 2008). Because of the complexity in determining oxygen directly, it was determined by difference, i.e. subtracting the total percentage of carbon, hydrogen, nitrogen and sulfur. The heating value was determined by an adiabatic bomb calorimeter as described in ASTM D 5865 (Miller & Tillman, 2008).


Table 7. Proximate analysis, ultimate analysis and other properties of PEFB (dry basis)

Regarding to the proximate analysis, the volatile matter of PEFB is rather high with the value of 79.82 %. Volatile matter indicates the portion driven off in gas or vapor form which comprises mainly hydrogen, oxygen, carbon monoxide, methane and other hydrocarbons (Miller & Tillman, 2008). The use of fuel with high volatile matter results in the low combustion temperature because some parts of heat is used to vaporize volatile matters in fuel. PEFB contains 8.34 % wt. moisture, 13.31 % wt. fixed carbon and 6.87 % wt. ash. The amount of fixed carbon represents the combustible residue after driving off the volatile matter (Miller & Tillman, 2008) and plays an important role on the amount of CO produced in the reduction zone, which is the main composition of producer gas. From the ultimate analysis, PEFB contains 43.80 % wt. carbon and 6.20 % wt. hydrogen. Both carbon and hydrogen effect the thermo-chemical conversion and then the producer gas composition. PEFB has low sulfur content of about 0.09 % wt. which indicates the tendency of SO2 and H2S formation. Other important parameters are bulk density and heating value which affect the gasification behavior and also the quality of producer gas.

In this study both *as received PEFB* and *pelletized PEFB* were used as feedstock. In order to prepare feedstock, as received PEFB was solar dried and cut into small size of 2 cm x 5 cm x 5 cm by cutting machine. In case of using pelletized PEFB as feedstock, pelletizing machine is used for preparing feedstock and the pelletized PEFB has a final diameter of approximately 5.5 cm and a length of 6 cm, as illustrated in Figure 9. The physical properties of pelletized PEFB compared to as received PEFB is listed in Table 8.

Proximate analysis

Ultimate analysis

Other properties

Regarding to the proximate analysis, the volatile matter of PEFB is rather high with the value of 79.82 %. Volatile matter indicates the portion driven off in gas or vapor form which comprises mainly hydrogen, oxygen, carbon monoxide, methane and other hydrocarbons (Miller & Tillman, 2008). The use of fuel with high volatile matter results in the low combustion temperature because some parts of heat is used to vaporize volatile matters in fuel. PEFB contains 8.34 % wt. moisture, 13.31 % wt. fixed carbon and 6.87 % wt. ash. The amount of fixed carbon represents the combustible residue after driving off the volatile matter (Miller & Tillman, 2008) and plays an important role on the amount of CO produced in the reduction zone, which is the main composition of producer gas. From the ultimate analysis, PEFB contains 43.80 % wt. carbon and 6.20 % wt. hydrogen. Both carbon and hydrogen effect the thermo-chemical conversion and then the producer gas composition. PEFB has low sulfur content of about 0.09 % wt. which indicates the tendency of SO2 and H2S formation. Other important parameters are bulk density and heating value which affect

In this study both *as received PEFB* and *pelletized PEFB* were used as feedstock. In order to prepare feedstock, as received PEFB was solar dried and cut into small size of 2 cm x 5 cm x 5 cm by cutting machine. In case of using pelletized PEFB as feedstock, pelletizing machine is used for preparing feedstock and the pelletized PEFB has a final diameter of approximately 5.5 cm and a length of 6 cm, as illustrated in Figure 9. The physical properties

Moisture (as received after solar drying) % wt. 8.34

Volatile matter % wt. 79.82

Fix carbon % wt. 13.31

Ash % wt. 6.87

C % wt. 43.80

H % wt. 6.20

O % wt. 42.65

N % wt. 0.44

S % wt. 0.09

Bulk density kg/m3 112.04

Lower Heating Value MJ/kg 19.25

the gasification behavior and also the quality of producer gas.

of pelletized PEFB compared to as received PEFB is listed in Table 8.

Table 7. Proximate analysis, ultimate analysis and other properties of PEFB (dry basis)

Unit Value

Fig. 9. PEFB before (a) and after (b) pelletizing


Table 8. Physical properties of pelletizing PEFB

From Table 8, it can be obviously observed that after pelletizing PEFB is denser and has higher density than as received PEFB because bulk PEFB is pressed and its structural bound attached to each other. This is the advantages of pelletized PEFB because it is cheap to handle, transport and store. Apart from handling and storing behavior, the bulk density is important for the performance of biomass gasification in fixed bed reactor (Knoef, 2005). During the pelletizing process some water containing in PEFB is driven out. These can lead to the decrease in moisture content of PEFB.
