E-3 Friction Loss of Pulp Suspensions in Pipe

APPENDIX D

The following gives supplemental information to that where I.P.D. mill capacity (metric tons per day), provided in the main text.
1. Capacity (flow), Q

where T.P.D.=mill capacity (short tons per day),
and
C consistency (oven-dried, expressed
as a percentage. not decimally).
If SI units are used, the following would apply:

where T.P.D.= mill capacity (metric tons per day),
and
C consistency (oven-dried, expressed as a percentage, not decimally).

2. Bulk velocity, V-

where Q capacity (U.S GPM).
A inside area of pipe (in2). and
D = inside diameter of pipe (in).

The following would apply if SI units are used:

where Q = capacity (m3/s),
A = inside area of pipe (mm2), and D = inside diameter of pipe (mm).
D = inside diameter of pipe (mm)

3. Multiplication Factor, F (.included in Equation 2 ) F=F₁x F₂ x F₃ x F₄ x F₅, (iv) where F = correction factor for temperature. Friction loss calculations are normally based on a reference pulp temperature of 95^oF (35^oC). The flow resistance may be increased or decreased by 1 percent for each 1.8^oF (1^oC) below or above 95^oF (35^oC), respectively. This may be expressed as follows:

F₁= 1.528 - 0.00556 T,
where T = pulp temperature (^oF), or

F₁ = 1.35-0.01 T,
where T = pulp temperature (^oC).
F₂ = correction factor for pipe roughness. This factor may vary due to manufactur-ing processes of the piping, surface roughness, age, etc. Typical values for PVC and stainless steel piping are listed below:

F₃ - 1.0 for PVC piping, F₂ -1.25 for stainless steel piping. Please note that the above are typical values; experience and/or additional data may modify the above factors.

F₃ = correction factor for pulp type. Typical values are listed below:

F₃ = 1.0 for pulps that have never been dried and reslurried, F₃ = 0.8 for pulps that have been dried and reslurried.

Note: This factor has been incorporated in the numerical coefficient, K, for the pulps listed in Table II. When using Table II, F₃ should not be used.

F₄ = correction factor for beating. Data have shown that progressive beating causes, initially, a small decrease in friction loss, followed by a substantial increase. For a kraft pine pulp initially at 725CSF and F₄ = 1.0, beating caused the freeness to decrease to 636 CSF and F₄ to decrease to 0.96. Progressive beating decreased the freeness to 300 CSF and increased F₄ to 1.37 (see K values in Table II). Some engineering judgement may be required.