woodchip.txt

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Wood and Chip Handling in Kraft Pulp and Paper Mills
April 1995

TNRCC Rule 116.111(3) in Regulation VI requires that Best Available Control Technology
(BACT) be applied to all facilities that must obtain a permit.  BACT determinations are made on a
case-by-case basis.  Current BACT guidelines for wood and chip handling in kraft pulp and paper
mills are:  
                          
Cutting is the process of cutting the long logs into usable segments.  Generally, logs are cut into
'long' segments or 'short' segments, depending on the requirements of the barkers and chippers. 
Both long and short segments may be utilized at the same facility.  
BACT:  Utilization of water (or equivalent) as necessary to prevent nuisance conditions.

Barking.The most common type of barking involves a horizontal rotating drum into which the cut
logs are placed.  The motion of the logs and the drum separate the bark from the log, and the bark
falls through slits in the side of the drum to a conveyor system.  The bark is then stockpiled for
use in the power boiler.  The logs are sent to storage to await chipping.
BACT:  Utilization of water (or equivalent) as necessary to prevent nuisance conditions.

Chipping sizes the logs into small chips that are suitable for cooking in the digestors.  This is most
often accomplished by pushing the log segments onto a rotating disc with blades.  The chips pass
through to a conveyor and are carried to a scalping screen to remove oversize material.
BACT:  Utilization of water (or equivalent) as necessary to prevent nuisance conditions.

Storage of the chips is usually in well maintained stockpiles that have automated feed systems
(augers or other equipment) to load conveyors.  Usually, a bulldozer is at work maintaining the
proper shape of the pile to allow the augers to function properly.
BACT:  Utilization of water (or equivalent) as necessary to prevent nuisance conditions.

Screening of the chipped material from the stockpiles removes the fines (sawdust) and sends the
material to the power boiler.  The accepted material is conveyed to the digestors.  Oversize is
usually sent to a rechipper for size reduction.
BACT:  Utilization of water (or equivalent) as necessary to prevent nuisance conditions.