An analysis of a paper machine circuit shown below yielded the following data:

Production rate 500 BDT/day

Total fibre, filler and additive flow to the machine 360 kg/min

Average solids content from couch system to fibre recovery 32 kg/min

Average solids content from press section to fibre recovery 2 kg/min

Paper machine headbox consistency 0.80 %

Backwater flow and consistency 49000 lpm at 0.15 %

3.1 Determine the following:

a) The amount of solid material leaving the paper machine system.

b) The solid mass flow (in kg/min) of all process streams.

c) First pass retention by 2 methods.

d) Machine retention.

e) System retention. 30

3.2 Comment on and explain the differences in the different retention metrics calculated.

3.3 How would the paper properties change if the FPR were increased? 5

3.4 How would you go about increasing the different retention metrics? 5

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