Slep Furnace
The Slep furnace (saddle-type) is a continuous vertical activation kiln. Carbonised material is fed at the top and travels downward under gravity without interruption — the process is continuous, not batch. Total residence time is 36–42 hours, of which about 30 hours are in the activation zone, where the material contacts a 850–950°C mixture of steam and flue gas in counter-current flow. The only cyclical element is heat reversal: the two regenerator banks alternate every 30–60 minutes and the gas flow reverses. The material itself never stops moving. This matters when sizing capacity and planning maintenance. Capacity and product Rated 0.5–2 t/h of finished activated carbon per unit. With coconut-shell char and an iodine value of 900–1100 mg/g, steam consumption is roughly 2.5–3.5 t per tonne of char and activation yield is 55–62%. Below 0.5 t/h the Slep design is not recommended — heat losses through the shell raise specific energy noticeably. Fit and non-fit Best for single-grade, continuous operation and granular carbon; plants with limited footprint and surplus steam. Not suitable for frequent grade changes (a changeover requires 3–5 days of cleaning) or for batch-level traceability. Four numbers to settle before quoting Annual operating hours (7200 three-shift / 4800 two-shift / 2400 one-shift); char particle size (8–20 mm, fines below 15%); steam pressure stability at 0.6–0.8 MPa; and the four finished-product specs — iodine value, methylene blue, ash and hardness — which together determine residence time.
