Palm Kernel Shell (PKS) exports from Indonesia and Malaysia are projected to exceed 5 million tons by 2026, with Japan serving as the primary market. As the leading producers of crude palm oil (CPO), Indonesia and Malaysia are also the largest exporters of PKS. It is anticipated that PKS will continue to gain more popularity and remain a major competitor to wood pellets in the global biomass fuel market. As a byproduct of palm oil mills, PKS is available in quantities reaching millions of tons and is more cost-effective than wood pellets.

However, beyond the large volumes required to meet export demand, PKS must also undergo technical processing or quality enhancement—specifically, the removal of impurities and drying to reduce its moisture content to below 20%. Given the substantial volumes—often reaching tens of thousands of tons per shipment—achieving this level of quality improvement presents its own challenge. Consequently, effective and efficient processing, based on an industrial-scale approach, is essential to meeting the target.

PKS Screening Machines

Exporters of palm kernel shells (PKS) common use screening machinery to remove impurities or foreign materials. To be acceptable for the export market, the level of such foreign material must be kept below 1%. There are two common types of PKS screening machines: vibrating screens and rotary screens.

Vibrating screens are more widely used due to their simpler construction, operation, and maintenance requirements. These machines typically have a processing capacity ranging from 80 to 100 tons of PKS input per hour. To achieve the desired level of cleanliness and particle size, the screening process is carried out in several stages.

In the first stage, large foreign materials—such as stones, plastic, and fibers—are rejected. In the second stage, the cleaned PKS product is obtained, while at the bottom, very fine PKS particles (undersize material) are separated as waste. Magnetic separators are also commonly integrated into the screening system to remove ferrous impurities and other metallic contaminants; these are typically installed on the belt conveyor before the PKS enters the screening machine.

Drying of Palm Kernel Shell

Next, the screened palm kernel shells are dried until their moisture content drops below 20%—ideally to around 15%. Every exporter also offers specifications that they are willing to guarantee. Naturally, higher specifications are more attractive to buyers. While PKS collected from palm oil mills can have a moisture content as high as 30%, the average is typically around 25%. The drying process is carried out manually, using an excavator to stir the material. It is conducted in stages and can span several days.

For every two-meter-high pile, an excavator stirs the PKS to ensure that the surfaces are evenly exposed to the sun’s heat. More material is then added to the pile, followed by further stirring, and this cycle continues. Weather conditions also significantly impact the drying process; if it is cloudy or rainy, the time required to dry the PKS increases even further.

If a high-capacity, continuous-operation drying system—such as a rotary dryer—is used, the production process for PKS intended for export can be significantly accelerated. This drying method not only eliminates dependence on weather conditions but also enhances the quality of the final PKS product. Internal flights (fins) within the rotary dryer ensure that the PKS material is evenly exposed to hot air for an adequate duration, resulting in a uniformly dried end product.

Furthermore, the capacity of the drying equipment, such as a rotary dryer, should be balanced with the capacity of the screening machinery. For instance, if the screening system produces 80 tons of clean PKS per hour, this output would then serve as the input for the drying system.

Heating Medium for PKS Drying Equipment

The heat source for the drying machine can be derived from various types of biomass waste, which are abundantly available in the palm oil industry—ranging from plantation residues such as leaves, fronds, and even palm trunks, to mill byproducts like empty fruit bunches (EFB). With appropriate combustion technology, this biomass waste can generate sufficient heat while producing environmentally friendly exhaust emissions.

Specifically, when EFB are processed using suitable combustion technology—such as a reciprocating grate system—the process not only yields optimal heat but also produces ash rich in potassium, making it highly suitable for use as fertilizer. In contrast, burning empty fruit bunches (EFB) in a simple incinerator—while still yielding potassium-rich ash—results in the loss of heat and generates significant smoke pollution. Nevertheless, incinerators are widely used for the disposal of empty fruit bunches, which pose a serious environmental risk.