52 Oil palm plant starts flowering and forming fruit after 2-3 years. The fruit
ripening process can be observed from the change of its skin color. The fruit will turn red orange when ripe. The oil content reaches maximum amount at the time
the fruit reaches its optimum ripeness. If too ripe, the fruit will be detached and fall from the bunch stalk.
The process of palm oil harvesting consists of cutting the ripen bunch, picking the fruits and transport the harvested bunch to the collection point and to
the mill. Harvesting criteria which should be consideredis the harvesting criterion, harvesting tool, rotation, harvesting system and crop quality.
- Harvesting criterion: harvesting criterion is an appropriate indication that can
help harvesters to cut the fruit at the optimum ripeness. Ripening index is when the fruit reach maximum oil content and minimum free fatty acids FFA. At
this time, the general criteria that are widely used are based on the number fruit group, i.e.a plants with age less than 10 years haveless than 10 fruits per fruits
group, and b plants with age more than 10 years old have 15-20 fruits per fruits group. However, in practice, people commonly use criteria with two fruits
groups per 1 kg FFB. One key factor to maintain the yieldvalue is to keep the value of FFA of CPO or CJCO under 5. Under this condition, the biodiesel
process can be carried out using transesterification reaction. If the FFA value is higher than 5, esterification process should be conducted first before
transesterification. The shorter the process will turn to higher yield.
- Harvesting method: Based on the plant height, there are three common methods to harvest palm oil in Indonesia. Squat with dodos is used to harvest palm oil
with 2-5 m height, standing using axe tool is used to harvest palm oil with 5-10 m height, and sickle with long handle egrek is used to harvest palm oil with
more than 10 m height. For ease of harvesting, the stem should be cut first and orderly arranged in the middle of gawangan.
- Harvesting preparation: To deal with harvesting season and in order to make the process run smoothly, collection results TPH should be prepared and the
transportation road should be improved.
7. Milling Stage
Crude palm oil as known as CPO is produced from the extraction of fruit mesocarp. As oil or fat, palm oil is a triglyceride, which is a compound of glycerol
with fatty acids. In accordance with the form of the fatty acid chain, palm oil includes an oleic-linoleat acid oil.
Harvested fresh fruit bunches FFB should be immediately processed. The process to obtain palm oil involves sterilization, threshing, cutting, and pressing.
Pressing process will produce a liquid phase oil and solid phase in the form of waste. Liquid phase still contains a lot of impurities such as sand and fibers that
need filtration and clarification to separate these impurities. FFB processing flow chart to produce CPO at palm oil milling plant in PTPN Kebun Unit Kertajaya
VIII
is shown in Appendix 5, and the mass and energy balance is shown in Appendix 6.
8. Biodiesel Production Stage
Simple biodiesel production process is shown in Figure 3.10. Biodiesel is made by reacting CPO with methanol through transesterification reaction and
53 under catalytic process to form ester compound with glycerin as byproduct. In
every unit of biodiesel production, 3.2 unit of energy is produced. This means, the absorption of solar energy into chemical energy in the biodiesel is very efficient.
Treatment at harvest greatly affects the content of free fatty acids FFA on the oil produced. Harvesting in over-mature produces oil with contain high
percentage of FFA 5. Conversely, if harvesting is done in an immature fruit, besides of low FFA levels, the process under this condition produces low oil yield.
In general, if the harvesting and processing are conducted properly, the FFA value from CPO will be under 5 so that the biodiesel processing does not need
transesterification process.
Figure 3.10 Block diagram of biodiesel production
Figure 3.11 Common biodiesel production flow diagrame using vegetable material Figure 3.11 shows common processing method to produce biodiesel using
vegetable material. Figures 3.12 and 3.13 show biodiesel production process using CPO as the feedstock without esterification reaction due to FFA value is lower
than 5. Figure 3.18 shows 3D layout on biodiesel milling plant with capacity 500 literbatch or about 1 ton per day in BRDST BPPT Puspitek Serpong. Figure
3.19 shows mass balance flow under catalytic process, while Figure 3.20 shows biodiesel production with capacity of 1 ton per day performed in BRDST BPPT
Puspitek Serpong
.
Reactor Neutraliz
ation and Methanol
removal Separator
Water washing
Acidulation and FFA
Separation Methanol
removal MethanolWater
rectification Dryer
Finished Biodiesel
Acid Water
Wash Water
Water Methanol
Storage Crude Glyserol
85 Free Fatty Acids
Acid Glyserol
50 Methanol
Oil Catalyst
Methyl ester
- 100 kg of CPO - 14 kg of methanol
- Catalyst Reaction and form
methyl ester - Methyl ester
Biodiesel 95 kg minimum - Glycerine 10 kg
- Methanol recovery - Other products
54
Figure 3.12 CPObased biodiesel processing process under transesterification reaction
Figure 3.13 Common CPO based biodiesel processing under two stages transesterification reaction in PT Adaro, Central Kalimantan
Detail description of production process in Figure 3.20 and 3.21 and the common method implemented in biodiesel industry, and also to analyze the flow
of mass, energyheat, and waste into the air, liquid waste and solid waste per sub unit process production under catalytic method using CPO is as follow:
1. Sub Unit of Immersed Coil Heater
This sub unit is used to heat CPO before entering centrifuge Figure 3.14.
Figure 3.14 Sub unit of immersed coil heater
Preparation Washing
Distillation Purification
Methanol Methanol
Drying Trans
esterification
Biodiesel
Separation Glycerol I
Purification Dehydration
Biodiesel
Transesterification Stage I
Catalyst alkali
Transesterification
Stage II
Catalyst of alkali
+
Methanol
Separation Glycerol II
Pinch
Methanol
Pinch
Glycerol
Raw Glycerol Salt fertilizer
Preparation
Washing and
CPO Catalyst
Alkaline
Glycerol
CPO
Methanol