Difference between revisions of "ASTM on Data Normalisation"
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| + | 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. | ||
| + | |||
| + | ==Flow or flux performance== | ||
| + | ===Specific flux=== | ||
| + | |||
<math> | <math> | ||
\operatorname{Specific Flux} = | \operatorname{Specific Flux} = | ||
| Line 43: | Line 50: | ||
</math> | </math> | ||
Permeate back pressure</p> | Permeate back pressure</p> | ||
| + | <p> | ||
| + | <math> | ||
| + | \pi = 0.006 \times | ||
| + | </math> | ||
| + | Average feed / brine conductivity</p> | ||
| + | <p> | ||
| + | <math> | ||
| + | \text {Average feed / brine conductivity} = \text {Conductivity of feed} \times \left [ \frac{\ln \left ( \frac{1}{1-Y} \right )}{Y} \right ] | ||
| + | </math> | ||
| + | </p> | ||
| + | <p> | ||
| + | <math> | ||
| + | Y = \text {Recovery} = \frac{\text {Permeate flow}}{\text {Concentrate flow} + \text {Permeate flow}} | ||
| + | </math> | ||
| + | </p> | ||
| + | |||
| + | ===Normalised Flow=== | ||
| + | <math> | ||
| + | \text {Normalised Permeate Flow} = \frac{\left ( NDPs \right ) \left ( TCFs \right )}{\left ( NDPa \right ) \left ( TCFa \right )} \text {Actual Flow} | ||
| + | </math> | ||
| + | <p> | ||
| + | <math> | ||
| + | a = \text {actual} | ||
| + | </math> | ||
| + | <br> | ||
| + | <math> | ||
| + | s = \text {standard} | ||
| + | </math> | ||
| + | </p> | ||
| + | |||
| + | ==Membrane rejection | ||
| + | |||
| + | ===Normalised Salt Rejection=== | ||
| + | |||
| + | ===Normalised Permeate Conductivity=== | ||
| + | <math> | ||
| + | \text {Normalised permeate conductivity} = \text {Permeate conductivity}\left ( \frac{\text {Actual permeate flow}}{\text {Standard permeate flow}} \right )\left ( \frac{\text {Standard feed/brine conductivity}}{\text {Actual feed/brine conductivity}} \right )\left ( TCF \right ) | ||
| + | </math> | ||
| + | |||
| + | ==Feed/brine channel blockage/fouling== | ||
| + | |||
| + | === Normalised differential pressure=== | ||
| + | <math> | ||
| + | \text {Normalised} \hspace {2mm} \Delta P=\Delta P\left [ \frac{\left ( \text {Standard feed/brine flow} \right )^{1.5}}{\left (\text {Actual feed/brine flow} \right )^{1.5}} \right ]\left [\left ( T-25 \right )\left ( 0.017 \right ) +1 \right ] | ||
| + | </math> | ||
| + | <p> | ||
| + | <math> | ||
| + | \text {Feed/brine flow}=\frac{\left ( \text {Feed flow} + \text {Concentrate flow} \right )}{2} | ||
| + | </math> | ||
| + | </p> | ||
| + | |||
| + | ==Calculators/spreadsheets== | ||
| + | Dow | ||
| + | http://www.dowwaterandprocess.com/en/resources/normalization_of_membrane_systems | ||
| + | Hydronautics | ||
| + | http://membranes.com/index.php?pagename=rodata | ||
[[Category:Training Material for Operators]] | [[Category:Training Material for Operators]] | ||
[[Category:Resources]] | [[Category:Resources]] | ||
Latest revision as of 06:45, 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 Conductivity
$ \text {Normalised permeate conductivity} = \text {Permeate conductivity}\left ( \frac{\text {Actual permeate flow}}{\text {Standard permeate flow}} \right )\left ( \frac{\text {Standard feed/brine conductivity}}{\text {Actual feed/brine conductivity}} \right )\left ( TCF \right ) $
Feed/brine channel blockage/fouling
Normalised differential pressure
$ \text {Normalised} \hspace {2mm} \Delta P=\Delta P\left [ \frac{\left ( \text {Standard feed/brine flow} \right )^{1.5}}{\left (\text {Actual feed/brine flow} \right )^{1.5}} \right ]\left [\left ( T-25 \right )\left ( 0.017 \right ) +1 \right ] $
$ \text {Feed/brine flow}=\frac{\left ( \text {Feed flow} + \text {Concentrate flow} \right )}{2} $
Calculators/spreadsheets
Dow http://www.dowwaterandprocess.com/en/resources/normalization_of_membrane_systems
Hydronautics http://membranes.com/index.php?pagename=rodata