




Broke System Purpose and Operation
“Broke” refers to partly or fully manufactured paper or board that is discarded from paper or board making, converting, and finishing processes. It also refers to the stock made by repulping these materials. Broke is continuously being produced, and it is the job of the “broke system” to collect this valuable resource, process it, and make it available for reuse. Because broke can amount to well over 5% of a machine’s total production, broke is an important fiber source and the broke system is an essential part of the papermaking process, from both financial and operational perspectives.
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Learning Objectives
• Describe the purpose of the broke system for a paper or board machine • List safety hazards and safety guidelines for broke systems • Identify how broke usage affects machine operations • Explain why broke consistency control is important • List ways to control contamination in broke systems • List sources of wet and dry broke • List the main differences between wet broke and dry broke repulpers • List the functions of repulper showers • Describe how operators maintain control of broke systems
Specs
Course Level | Intermediate |
Languages | English, Portuguese, French, Russian, Spanish |
Compatibility | Audio, Video |
Based on: | Industry Standards and Best Practices |
Key Questions
Why is it important to feed broke back into the system in a controlled manner?
Broke behaves differently than virgin fiber – it holds less water, so dries more easily. However, it can negatively affect sheet quality and machine runnability, so the amount used needs to take into account all of its effects.
Why is wet broke easier to repulp than dry broke?
Wet broke is more easily rewetted and repulped because its moisture content is already much higher.
What are the differences between under-machine repulpers at the wet end and dry end?
Dry end repulpers are usually of heavier duty construction so they can handle large slabs of broke. They are usually larger to allow for the extra retention time needed to properly slush dry broke.
How much broke storage should a paper or board machine be equipped with?
Ideally, a broke storage system would be able to handle around 2 hours of full machine production, though in reality it is usually much less.
Why is it important to control consistency during repulping?
Repulpers are designed to create a vortex that draws broke down to the rotor blade. If the consistency is too low, there will be excessive turbulence, but if the consistency is too high, the suction effect of the vortex will be weakened.
Sample Video Transcript
Broke collected from the paper or board making process can be collected and slushed in under-machine or off-machine repulpers. Under-machine repulpers are located in the basement under sections of the paper or board machine. For example, a paper or board machine may have a Couch Pit, Press Pit, and Dry End repulper. Winders and converting facilities may have their own dedicated repulpers, or they may return their broke to the dry-end repulper. Off-machine repulpers can be located virtually anywhere, but they are usually located close to their sources of broke.
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