Log Handling and Chip Storage
The raw material for pulping, wood, is received, stored and processed in a largely outdoor area of the mill called the woodyard. Wood may be received as whole logs, or as wood chips. While the operations performed in the woodyard are apparently quite basic, how well they perform is quite important to the successful operation of the pulp mill. Mistakes made in the woodyard can have a significant overall economic impact. This module describes the three major operations in the woodyard: removal of bark, chipping or grinding of logs into smaller pieces, and storage and retrieval of chips.
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Learning Objectives
• Describe the role of a woodyard
• Identify hazards within the woodyard
• Identify and describe problems associated with bark in the pulping process
• Describe the operating principles of different types of debarkers
• Identify and describe the components of debarkers
• Identify and describe the components of a disk chipper
• Describe the operation of a disk chipper
• Describe the difficulties encountered with outdoor chip storage
• Identify methods for reducing chip storage problems
Specs
| Course Level | Intermediate |
| Languages | English, Portuguese, French |
| Compatibility | Audio, Video |
| Based on: | Industry Standards and Best Practices |
Key Questions
Why does bark need to be removed from logs prior to pulping?
Bark contains dirt which will cause equipment wear and has high levels of resin and extractives which will consume disproportionate amounts of cooking and bleaching chemicals.
What is the most common type of debarker currently used?
The drum type debarker is the most common type of debarker.
What advantage do belt conveyors have over pneumatic chip transport systems?
Conveyor belt systems do not break and degrade the chips as much as pneumatic systems.
What is one of biggest problems encountered with long term chip storage?
Being an organic material, wood chips are subject to attack and breakdown by microorganisms during storage.
What are some advantages of an automated chip storage and retrieval system?
Automated storage and retrieval minimizes physical damage to the chips caused by loader traffic, and also assures a more uniform storage time.
Sample Video Transcript
Ring and Rosserhead debarkers operate on a single log at a time. In a ring debarker, a set of hinged scraper fingers rotate in a single plane perpendicular to the log. Log feeders push and pull the log through the fingers. As the fingers rotate around the log, they scrape and pull the bark from it. A Rosserhead debarker rotates a log while an arm with a high-speed rotary tool moves down the length of the log grinding off the bark as it goes. This type of debarker is good for frozen logs or types of wood with high adhesion bark but tends to have higher losses of good wood. These single log debarkers are more labor intensive than the multi-log debarkers.
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