Pipes, pulping, detrashing Flashcards
(15 cards)
What is the average fresh water consumption per kg of paper
Roughly 7Kg water per Kg paper
What is the task of stock prep
Provide homogenous fibre suspension with the desired quality, cleanliness and composition
What does piping need to be adjusted to
Pressure (Wall thickness)
Fluid properties (Pipe material)
Flow velocity (Pipe dimension)
What are some tips on pipe guiding
Distances should be short as possible
Least elbows/bends
slope if necessary (reject lines)
What does the DN number of a pipe tell you?
The size of the pipe.. Nominal diameter. Gives the rough measurment of diameter inside pipe in mm
Is a small pipe more or less efficient than a big pipe, explain resoning
Smaller pipes ‘cost’ more energy as they will need more speed and have more friction therefore energy loss
What does pressure loss mean in a pipe
We lose energy in pipes through friction and turbulence, this translates into pressure loss. Scale (roughness) is big factor
What are the 4 main purposes of pulping?
Disintegration /Defibering
- Ink-Detatchment
- Mixing / Homogenization
- Contaminant Removal
What is typical consistency of LC pulper
Below 7 usually 4-5%
What is typical consistency of HC pulper
between 15-25%
What is typical consistency of drum pulper
more than 18%
What is the ragger rope for?
To capture spinning contaminants from raw material, formed by vortex movement in pulper
How would you describe a detrasher unit
As a secondary pulper. Like a pulper but horizontal and very high shear
Why are HC pulpers often used in deinking mills
Less water to interfere with chemistry (>15%). And we don’t want to break ink particles a lot, gentle remove with fibre to fibre friction
Why wouldn’t you use HC pulper in OCC mill
Too much contamination would wrap around helical rotor
