• Case Studies
Emission Control

Biomass Milling & Drying

The drying of biomass is common to many industries, including wood pellet making, panel boards and many others, from coffee to olive-oil or animal feed. Technologically, these industries operate drum / rotary dryers to dry biomass. It can be a raw-material or a fuel for the manufacturing process.

The pellet making industry presents a typical general arrangement which is replicated in other industries. It includes a “dryer” cyclone after a rotary dryer which is heated by a furnace (generally burning biomass). Usually, a fraction of air is recirculated back to the dryer for energy recovery.
Most of the coarser particles (Median Volume Diameter (MVD) >100µm) are recovered in the dryer cyclone but many of the fines and the fly ash from combustion end up in the stack. Their much lower size (MVD ~15µm) forces clients to use a final dedusting system to comply with stricter emission limits.

Typically, Wet Venturi Scrubbers or, in more environmentally strict cases, WESPs are used to reduce emissions under 50mg/Nm3, though with significant drawbacks. Scrubbers imply very high energy costs due to very high pressure drops. WESPs work with low pressure drops but have high OPEX and CAPEX. Ultimately both require the use of water, originating secondary pollution.

Clients' needs include a highly efficient and dry final dedusting system at a reasonable price, robust enough to operate for several years without significant maintenance and operating costs and avoiding production downtime.

ACS solutions include low pressure drop, efficient and long-lasting dryer cyclones and high efficiency secondary cyclones which are a real alternative to other more maintenance demanding or costly dedusters to reach emissions as low as 30mg/Nm3. Please see our case studies for several specific industrial segments.