Palm kernel shell from yard to furnace: moisture, screening, tramp iron, conveying
Palm kernel shell must pass four gates on the way from the yard to the furnace: moisture control, screening, tramp-iron removal and buffered conveying. Lose any gate and the carbonization zone starves or fouls, and activation quality follows. This page gives a copy-ready configuration table and checklist.
The conclusion first: most feed problems sit in front of the furnace, not inside it
Palm kernel shell (PKS) reaches the furnace reliably only after four gates: moisture control, screening, tramp-iron removal and buffered conveying. Lose any one and the carbonization zone starves or fouls, and iodine value at activation follows. This page gives a configuration table and a duty checklist you can copy directly.
PKS is one of the most common activated-carbon feedstocks in Southeast Asia, but its physical behaviour is hostile to conveying systems: shell-shaped particles that roll easily, fibres that tangle when wet, moisture that swings widely with origin, season and storage, plus sand, stones and ferrous objects picked up during bulk transport and lifting. These traits mean PKS cannot be treated like charcoal - you cannot simply dump it into a hopper and expect steady flow.
The most common field situation looks like this: the furnace itself is fine, yet the complaints are about output that never reaches nameplate and temperatures that swing. Trace the problem back and it usually sits in yard management and front-of-furnace conveying - the four gates this page covers. How pretreatment equipment is arranged is described on our auxiliary equipment page; how feedstock traits steer furnace selection is covered on the carbonization furnace page.
The four gates: target, typical equipment and what failure looks like
| Gate | Control target | Typical equipment | What failure looks like |
|---|---|---|---|
| Moisture | Feed moisture down to the process-approved value (commonly below 15%, per duty) | Covered shed, batch drying on the yard, drum dryer when needed; per-batch moisture tests | Carbonization temperature will not hold, char yield drops, off-gas load rises |
| Screening | Uniform feed size with fines and oversize separated (commonly 10-30 mm class, per furnace model) | Trommel or vibrating screen; oversize crushed then re-screened | Bridging in bins, uneven carbonization, fines lost with the off-gas |
| Tramp iron | Remove bolts, wire, shed crusher hammers and other ferrous objects | Overband magnet plus magnetic bars in chutes, after crushing and before the incline | Jammed feeders, torn belts, local overheating when iron enters the furnace |
| Buffered conveying | Stable furnace-front level and steady feed rate; buffer sized per shift plan | Furnace-front buffer bin with level sensor, variable-speed feeder | Starvation shutdowns, wide temperature swings, uneven shift output |
Operating points for each gate: a checklist to copy
- **Moisture.** As-received PKS commonly swings between 15% and 25% moisture (depending on origin, season and handling); the feed target is usually below 15% (per process approval). The cheapest first step is not drying - it is a covered shed and batch drying on the yard. Sample every delivery, log the moisture, mark the yard by batch and use first-in-first-out. Only add a dryer when yard drying misses the target; that is how the energy account stays honest.
- **Screening.** Set the screen aperture against the carbonization furnace's feed specification, not against somebody else's numbers. Crush oversize first, then re-screen. Do not blend the screened fines straight back into the feed: fines burn fast in the carbonization zone, escape with the off-gas, and you lose on both char yield and dust load. Collect them separately and sell them or burn them as fuel.
- **Tramp iron.** Put the magnet after the crusher and before the feed incline - that position catches both iron that came with the raw material and iron your own crusher sheds. Clean the magnetic bars by hand once a month and keep records; if the recovered iron suddenly increases, your crusher is shedding parts, so go back and check hammers and liners.
- **Conveying.** PKS rolls: belt inclines that are too steep simply send it back down. Switch to a bucket elevator or increase the trough angle when needed. The furnace-front buffer bin needs a level sensor - when level drops below the low limit the feeder slows automatically and alarms. Do not run this on an operator watching a sight glass. The full equipment list sits on the auxiliary equipment page.
The most expensive mistake: pushing wet feed through
When moisture runs high, the common response is to push more feed to hold output. The carbonization temperature gets dragged down by evaporating water, operators add more heat, and parts of the furnace overheat and foul. The heat spent drying wet feed does no useful work, char yield and product quality fall together, and the off-gas load climbs. The correct response is to stop feeding, reduce load, find out what the moisture actually is, fix the water problem, and only then restore output.
How the four gates shape carbonization and activation
Moisture is factor number one. The carbonization zone works at 450-550 C (per duty); wet feed means hauling water into the furnace just to boil it off, so heat consumption rises and effective residence time shrinks. Carbonization residence is controlled at 30-60 minutes (per duty), and moisture swings directly disrupt that rhythm. Char yield typically lands in the 28-34% band (per duty), and moisture is the variable that drags it down fastest.
Screening and iron removal govern stability. Non-uniform particle size makes carbonization run unevenly, and escaping fines load up the off-gas dedusting. Iron entering the furnace is one of the most direct causes of local overheating - at worst it means a shutdown to clean out.
Buffered conveying decides whether the line's rated output is actually delivered. Whether the design sits at the low or high end of the 0.5-3 t/h range (per duty), pretreatment and conveying must be sized for the maximum, not the average - the feedstock side is always the bottleneck of the whole line. Take a 1 t/h line as an example: yard, screening, magnets and buffer bin each need headroom above the rated throughput; the basis is set out on the 1 t/h capacity page.
Hold the four gates and the reports downstream - carbonization temperatures, activation iodine values, yields - stay smooth. Read it backwards when something moves: if iodine value or yield suddenly swings, walk the investigation from the furnace front inward - moisture logs and bin levels first, temperature curves second. More often than not, the answer is in the yard, not in the furnace.
Related notes
Send the raw material, target tonnage and finished spec. You get a configuration, a utility schedule and a budget range — not a brochure.