Difference between revisions of "ASTM on Data Normalisation"
(→Normalised Flow) |
|||
Line 67: | Line 67: | ||
===Normalised Flow=== | ===Normalised Flow=== | ||
+ | <math> | ||
+ | \text {Normalised Permeate Flow} = \frac{\left ( NDPs \right ) \left ( TCFs \right )}{\left ( NDPa \right ) \left ( TCFa \right )} \text {Actual Flow} | ||
+ | </math> | ||
+ | <math> | ||
+ | a = \text {actual} | ||
+ | </math> | ||
+ | <math> | ||
+ | s = \text {standard} | ||
+ | </math> | ||
==Membrane rejection - normalised salt rejection, normalised permeate== | ==Membrane rejection - normalised salt rejection, normalised permeate== |
Revision as of 02:26, 16 September 2014
ASTM D4516 - Standard Practice for Standardizing Reverse Osmosis Performance Data
Membrane performance (flux and salt passage) is affected by: water temperature, feed conductivity, and flux rate. If the operating arameters remain constant the system will perform fairly steadily over a long period of time. However, these operating conditions will eventually change. Normalisation is a technique that allows the user to standardise the data to a constant set of conditions (or to a reference), and may be used with SCADA for online diagnostics.
Contents
Flow or flux performance
Specific flux
$ \operatorname{Specific Flux} = \frac{Flux \times TCF}{NDP} $
Where: $ \operatorname{TCF} = e^{x} $
$ x = u\left( \frac{1}{T+273} - \frac{1}{298}\right ) $
NDP = Net Driving Pressure
$ NDP = P_{feed}-\Delta \pi-\frac{\Delta P}{n+1}-P_{permeate} $
$ P_{feed} = $ RO feed pressure
$ \Delta \pi = $ Osmotic Pressure
$ \Delta P = $ Feed/Brine Differential Pressure
$ n+1 = $ Number of membrane stages
$ P_{permeate} = $ Permeate back pressure
$ \pi = 0.006 \times $ Average feed / brine conductivity
$ \text {Average feed / brine conductivity} = \text {Conductivity of feed} \times \left [ \frac{\ln \left ( \frac{1}{1-Y} \right )}{Y} \right ] $
$ Y = \text {Recovery} = \frac{\text {Permeate flow}}{\text {Concentrate flow} + \text {Permeate flow}} $
Normalised Flow
$ \text {Normalised Permeate Flow} = \frac{\left ( NDPs \right ) \left ( TCFs \right )}{\left ( NDPa \right ) \left ( TCFa \right )} \text {Actual Flow} $ $ a = \text {actual} $ $ s = \text {standard} $
Membrane rejection - normalised salt rejection, normalised permeate
Feed/brine channel blockage/fouling - normalised differential pressure
Calculators/spreadsheets
Dow http://www.dowwaterandprocess.com/en/resources/normalization_of_membrane_systems
Hydronautics http://membranes.com/index.php?pagename=rodata