Difference between revisions of "ASTM on Data Normalisation"

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(Normalised differential pressure)
 
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<math>
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ASTM D4516 - Standard Practice for Standardizing Reverse Osmosis Performance Data
  \operatorname{erfc}(x) =
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  \frac{2}{\sqrt{\pi}} \int_x^{\infty} e^{-t^2}\,dt =
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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.
  \frac{e^{-x^2}}{x\sqrt{\pi}}\sum_{n=0}^\infty (-1)^n \frac{(2n)!}{n!(2x)^{2n}}
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</math>
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==Flow or flux performance==
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===Specific flux===
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<math>
 
<math>
 
\operatorname{Specific Flux} =  
 
\operatorname{Specific Flux} =  
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e^{x}
 
e^{x}
 
</math>
 
</math>
<br>
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</p><p>
 
<math>
 
<math>
 
x = u\left( \frac{1}{T+273} - \frac{1}{298}\right )
 
x = u\left( \frac{1}{T+273} - \frac{1}{298}\right )
 
</math>
 
</math>
<br>NDP = Net Driving Pressure
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</p><p>NDP = Net Driving Pressure</p><p>
 
<math>
 
<math>
 
NDP = P_{feed}-\Delta \pi-\frac{\Delta P}{n+1}-P_{permeate}
 
NDP = P_{feed}-\Delta \pi-\frac{\Delta P}{n+1}-P_{permeate}
 
</math>
 
</math>
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</p>
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<p>
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<math>
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P_{feed} =
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</math>
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RO feed pressure</p>
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<p>
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<math>
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\Delta \pi =
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</math>
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Osmotic Pressure</p>
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<p>
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<math>
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\Delta P =
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</math>
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Feed/Brine Differential Pressure</p>
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<p>
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<math>
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n+1 =
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</math>
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Number of membrane stages</p>
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<p>
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<math>
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P_{permeate} =
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</math>
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Permeate back pressure</p>
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<p>
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<math>
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\pi = 0.006 \times
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</math>
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Average feed / brine conductivity</p>
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<p>
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<math>
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\text {Average feed / brine conductivity} = \text {Conductivity of feed} \times \left [ \frac{\ln \left ( \frac{1}{1-Y} \right )}{Y} \right ]
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</math>
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</p>
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<p>
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<math>
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Y = \text {Recovery} = \frac{\text {Permeate flow}}{\text {Concentrate flow} + \text {Permeate flow}}
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</math>
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</p>
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===Normalised Flow===
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<math>
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\text {Normalised Permeate Flow} = \frac{\left ( NDPs \right ) \left ( TCFs \right )}{\left ( NDPa \right ) \left ( TCFa \right )} \text {Actual Flow}
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</math>
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<p>
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<math>
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a = \text {actual}
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</math>
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<br>
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<math>
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s = \text {standard}
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</math>
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</p>
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==Membrane rejection
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===Normalised Salt Rejection===
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===Normalised Permeate Conductivity===
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<math>
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\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 )
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</math>
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 +
==Feed/brine channel blockage/fouling==
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 +
=== Normalised differential pressure===
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<math>
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\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 ]
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</math>
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<p>
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<math>
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\text {Feed/brine flow}=\frac{\left ( \text {Feed flow} + \text {Concentrate flow} \right )}{2}
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</math>
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</p>
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==Calculators/spreadsheets==
 +
Dow
 +
http://www.dowwaterandprocess.com/en/resources/normalization_of_membrane_systems
 +
 +
Hydronautics
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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.

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