Valmet Chip Bin is a buffer that acts as a feeding device to the plug screw feeder. It can act both as a buffer and pre-steaming bin, but also Whilst the chips are inside the bin, they will undergo equalization of moisture and temperature to create a highly homogenous chip content.
Reduced evaporation in the dryer with presteaming
Natural rosin reduction
The homogenous chip content can be further processed by combining the Valmet Chip Bin with pre-steaming, this will result in an increased temperature and moisture level of the chip content to facilitate the upcoming process step like dewatering, refining and reducing the amount of natural wood resins. Ensuring proper dewatering starts with the removal of trapped gases inside the chips and replacing them with steam. Allowing that steam to condensate inside the chip completes the replacement of a non-compressible media with a compressible one, water. This change will allow for a far more effective dewatering when the chips are moving forward to the dewatering zone of the plug screw feeder.
Valmet offers two types of chip bins, the Chip Bin VB (Vibrating Bin) that uses gravity and vibrational energy to control the feeding and the Chip Bin DB (Discharge Bin) which uses a screw conveyor and agitator to actively control the feeding.
Valmet Chip Bin VB
Valmet Chip bin VB is a conical chip bin primarily designed to handle raw materials with favorable flow characteristics, normally seen with a even sizes and shape distribution. It should also be relatively free from impurities such as sawdust, shavings, bark and pin chips since their presence greatly increases the risk of bridging, especially when used with pre-steaming.
The main purpose of pre-steaming is to level out incoming moisture variations and enable a more efficient dewatering in the plug screw feeder. This saves load on the dryer and increases the lifetime of the plug screw. Efficient pre-steaming leads to a better total steam consumption.
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