Repurposing equipment can introduce constraints that were not part of its original duty. At a biochar facility assessed by CPE, a triple-pass dryer being used as a pyrolysis reactor was producing excessive fines and experiencing mechanical problems.
The drum arrangement placed the hottest zone in the outer pass and required upward material transfer between zones. This encouraged internal recirculation and attrition, increasing the fines reaching the downstream cyclones.
The assessment also found trunnion runners, or tires, welded directly to the shell, with cracking associated with differential thermal expansion. Available movement at another support was limited for the hotter conditions being considered.
CPE recommended reversing the drum orientation to improve material transfer, redesigning the runner arrangement to accommodate shell expansion and modifying the discharge trunnion assembly.
The recommendations addressed material flow and mechanical behavior together. Their intended benefits were reduced fines generation and a more reliable basis for increased production, with performance to be verified after modification.
CPE's feasibility assessments evaluate whether existing equipment can support a proposed process and what changes that duty requires.